• Title/Summary/Keyword: health system

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Retrieval of Hourly Aerosol Optical Depth Using Top-of-Atmosphere Reflectance from GOCI-II and Machine Learning over South Korea (GOCI-II 대기상한 반사도와 기계학습을 이용한 남한 지역 시간별 에어로졸 광학 두께 산출)

  • Seyoung Yang;Hyunyoung Choi;Jungho Im
    • Korean Journal of Remote Sensing
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    • v.39 no.5_3
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    • pp.933-948
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    • 2023
  • Atmospheric aerosols not only have adverse effects on human health but also exert direct and indirect impacts on the climate system. Consequently, it is imperative to comprehend the characteristics and spatiotemporal distribution of aerosols. Numerous research endeavors have been undertaken to monitor aerosols, predominantly through the retrieval of aerosol optical depth (AOD) via satellite-based observations. Nonetheless, this approach primarily relies on a look-up table-based inversion algorithm, characterized by computationally intensive operations and associated uncertainties. In this study, a novel high-resolution AOD direct retrieval algorithm, leveraging machine learning, was developed using top-of-atmosphere reflectance data derived from the Geostationary Ocean Color Imager-II (GOCI-II), in conjunction with their differences from the past 30-day minimum reflectance, and meteorological variables from numerical models. The Light Gradient Boosting Machine (LGBM) technique was harnessed, and the resultant estimates underwent rigorous validation encompassing random, temporal, and spatial N-fold cross-validation (CV) using ground-based observation data from Aerosol Robotic Network (AERONET) AOD. The three CV results consistently demonstrated robust performance, yielding R2=0.70-0.80, RMSE=0.08-0.09, and within the expected error (EE) of 75.2-85.1%. The Shapley Additive exPlanations(SHAP) analysis confirmed the substantial influence of reflectance-related variables on AOD estimation. A comprehensive examination of the spatiotemporal distribution of AOD in Seoul and Ulsan revealed that the developed LGBM model yielded results that are in close concordance with AERONET AOD over time, thereby confirming its suitability for AOD retrieval at high spatiotemporal resolution (i.e., hourly, 250 m). Furthermore, upon comparing data coverage, it was ascertained that the LGBM model enhanced data retrieval frequency by approximately 8.8% in comparison to the GOCI-II L2 AOD products, ameliorating issues associated with excessive masking over very illuminated surfaces that are often encountered in physics-based AOD retrieval processes.

A Study on Medical Waste Generation Analysis during Outbreak of Massive Infectious Diseases (대규모 감염병 발병에 따른 의료폐기물 발생량 예측에 관한 연구)

  • Sang-Min Kim;Jin-Kyu Park;In-Beom Ko;Byung-Sun Lee;Sang-Ryong Shin;Nam-Hoon Lee
    • Journal of the Korea Organic Resources Recycling Association
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    • v.31 no.4
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    • pp.29-39
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    • 2023
  • In this study, an analysis of medical waste generation characteristics was conducted, differentiating between ordinary situation and the outbreaks of massive infectious diseases. During ordinary situation, prediction models for medical waste quantities by type, general medical waste(G-MW), hazardous medical waste(H-MW), infectious medical waste(I-MW), were established through regression analysis, with all significance values (p) being <0.0001, indicating statistical significance. The determination coefficient(R2) values for prediction models of each category were analyzed as follows : I-MW(R2=0.9943) > G-MW(R2=0.9817) > H-MW(R2=0.9310). Additionally, factors such as GDP(G-MW), the number of medical institutions (H-MW), and the elderly population ratio(I-MW), utilized as influencing factors and consistent with previous literature, showed high correlations. The total MW generation, evaluated by combining each model, had an MAE of 2,615 and RMSE of 3,353. This indicated accuracy levels similar to the medical waste models of H-MW(2,491, 2,890) and I-MW(2,291, 3,267). Due to limitations in accurately estimating the quantity of medical waste during the rapid and outbreaks of massive infectious diseases, the generation unit of I-MW was derived to analyze its characteristics. During the early unstable stage of infectious disease outbreaks, the generation unit was 8.74 kg/capita·day, 2.69 kg/capita·day during the stable stage, and an average of 0.08 kg/capita·day during the reduction stage. Correlation analysis between generation unit of I-MW and lethality rates showed +0.99 in the unstable stage, +0.52 in the stable stage, and +0.96 in the reduction period, demonstrating a very high positive correlation of +0.95 or higher throughout the entire outbreaks of massive infectious diseases. The results derived from this study are expected to play a useful role in establishing an effective medical waste management system in the field of health care.

Development of an evaluation tool for dietary guideline adherence in the elderly (노인의 식생활지침 실천 평가도구 개발)

  • Young-Suk Lim;Ji Soo Oh;Hye-Young Kim
    • Journal of Nutrition and Health
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    • v.57 no.1
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    • pp.1-15
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    • 2024
  • Purpose: This study aimed to develop a comprehensive tool for assessing dietary guideline adherence among older Korean adults, focusing on the domains of food and nutrient intake, eating habits, and dietary culture. Methods: Candidate items were selected through a literature search and expert advice. The degree of adherence to dietary guidelines was then evaluated through a face-to-face survey conducted on 800 elderly individuals across five nationwide regions. The items for dietary guideline adherence evaluation tool were selected through exploratory factor analysis of the candidate items in each of the three areas of the dietary guidelines, and construct validity was verified by performing confirmatory factor analysis. Using the path coefficient of the structural equation model, weights were assigned to each area and item to calculate the dietary guideline adherence score. A rating system for the evaluation tool was established based on national survey results. Results: A total of twenty-eight items were selected for evaluating dietary guideline adherence among the elderly. Thirteen items related to food intake, seven to eating habits, and eight to dietary culture. The average score for dietary guideline adherence was 56.9 points, with 49.8 points in the food intake area, 63.2 points in the eating habits area, and 58.6 points in the dietary culture area. Statistically significant correlations were found between dietary guideline adherence scores and food literacy (r = 0.679) and nutrition quotient scores (r = 0.750). Conclusion: The developed evaluation tool for dietary guideline adherence among Korean older adults can be used as a simple and effective instrument for comprehensively assessing their food and nutrient intake, dietary habits, and dietary culture.

Epidemiological Characteristic and Risk Factor of COVID-19 Cluster Related to Educational Facilities in Gangwon-do, Korea (December 10, 2020-September 23, 2021) (강원도내 교육시설관련 코로나바이러스감염증19 집단발생의 역학적특성과 위험요인 (2020.12.10-2021.9.23))

  • Hyosug Choi;Mi Young Kim;Shinyoung Lee;Eunmi Kim;Yeo Jin Kim
    • Pediatric Infection and Vaccine
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    • v.31 no.1
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    • pp.102-112
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    • 2024
  • Purpose: To identify the epidemiological characteristics and risk factors of coronavirus disease 19 (COVID-19) outbreaks depending on the type of educational facility by analyzing the COVID-19 cluster associated with educational facilities. Methods: This study is based on epidemiological investigation of COVID-19 cluster in Gangwon-do, Korea from December 10, 2020 to September 23, 2021 reported to the Korea Disease Control and Prevention Agency's Integrated Disease and Health Management System. Four hundred seven patients in 19 facilities, classified as cluster related to educational facilities, were the study population. The result of preliminary epidemiology survey report, in-depth epidemiological survey by phone and the result of risk assessment derived from the field epidemiology investigation were retrospectively analyzed to evaluate infectivity and the characteristics of the risk factors. Results: There were total of 407 confirmed patients related to 19 educational facilities, with 204 students under the age of 19 (50.1%). One hundred fifty-five preceding spreaders were from families (38.1%) and 125 were the teachers (30.7%). The place exposed to confirmed patients was the highest with 139 people (34.2%) at home. Conclusions: It was confirmed that the cause of the occurrence of clusters related to educational facilities was higher due to family transmission than the risk of facilities in schools. Nevertheless, continuous efforts should be made to control infection in educational facilities, and that teachers' implementation of principles for prevention of COVID-19 personal hygiene in their daily lives should be strengthened.

Halitosis and Related Factors among Rural Residents (농촌지역 주민들의 구취실태와 유발요인)

  • Lee, Young-Ok;Hong, Jung-Pyo;Lee, Tae-Yong
    • Journal of Oral Medicine and Pain
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    • v.32 no.2
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    • pp.157-175
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    • 2007
  • This study was conducted through an interview process in which questionnaires were administered to 293 people. The questionnaires related to the behaviors of oral hygiene care, and disease history related to halitosis, and status of halitosis, halitosis measurement, oral examination, and caries activity tests such as the snyder test, Salivary flow rate test, and Salivary buffering capacity test. Our sample was taken from 293 rural residents within the period from 4th to 21st of January 2006. This was done in order to provide basic data to prepare both policies of halitosis prevention and a device to efficiently measure halitosis status and investigate the factors related therein. The major findings of this study results are as follows: 1. As for frequency of tooth brushing, twice a day occupied the greatest portion at 46.1 % Women exceeded men in frequency of tooth brushing. Tongue brushing everyday produced a 25.6 % result among subjects and The use of auxiliary oral hygiene devices occupied 9.2 %. 2. As for degree of usual self-awareness of halitosis: 62.5 %. This result also demonstrate that the severest time of self-awareness in regards to halitosis is wake up time in the morning. The time period produced the highest portion of 72.7 % in times of self-awareness. In terms of the area in which halitosis was observed, gum resulted in 23.0 %. As for types of halitosis, fetid smell was the most frequent at 37.2 %. 3. As for the result of halitosis measurement, values of OG less than 50 ppm occupied 54.3 % and $50{\sim}100ppm$ occupied 41.6 %. As for $NH_3$ values, $20{\sim}60ppm$ showed the highest value range of 52.6 %. 4. As for OG per disease history related to halitosis, values of OG were significantly high in the ranges of $50{\sim}100ppm$ within family history groups of food impaction by dental caries, diabetes mellitus and halitosis. As for values of $NH_3$, there showed a significant difference in respiratory system disease groups. 5 Value range of OG per ordinary halitosis self-awareness degree: values ranging less than 50 ppm were recorded at 55.9 % from the group realizing not aware of smell. 57.5 % from groups only realizing sometimes, while values range of $50{\sim}100ppm$ were recorded at 52.0 % from groups always aware of smell. 63.6 % from groups always strongly aware of smell. Meanwhile as for the values ranges of $NH_3$, $20{\sim}60ppm$. they occupied high portions for all groups of exams. 6. Values of OG per oral examination: the more pulp-exposed teeth and food impaction and the higher the tongue plaque index, values of OG increased within the range of $50{\sim}100ppm$. As for values of $NH_3$, the more prosthetic teeth and the higher the tongue plaque index, this value increased significantly, and the values increased up to no less than 60 ppm for groups of mandibular partial denture. 7. Within the realm of caries activity test: as for the Snyder test, high activity was highest by 43.0 % wherewith the higher the activity of acidogenic bacteria the higher the OG values. As for the salivary flow rate test, the number of cases below 8.0 ml showed the highest tendency by 62.5 %. The larger the salivary flow rate the more decreased OG values distribution. As for the salivary buffering capacity test, $6{\sim}10$ drops of 0.1N lactic acid showed the overwhelming trend by 58.7 % whereby the higher the salivary buffering capacity the greater distribution occupancy ratio of OG values below 50 ppm which is scentless to on ordinary person. 8. As for the correlation between oral environment and halitosis, OG showed the positive correlation with pulp exposed teeth, filled teeth, present teeth, tongue plaque index, and food impaction, while the negative correlation with salivary flow rate and prosthetic teeth. $NH_3$ showed a positive correlation with prosthetic teeth and frequency of tooth brushing, while decayed teeth was negative correlation. 9. As for the multiple regression analysis result, there have been selected female, pulp exposed teeth, prosthetic teeth, food impaction, salivary flow rate, tongue plaque index and severe activities in the Snyder test as factors affecting OG wherein explanatory power on it was 45.1 %. There have been selected females, pulp exposed teeth, tongue plaque index, and prosthetic teeth as factors affecting on $NH_3$ wherein explanatory power on it was 6.6 %. With the aforementioned results in mind, the status of halitosis among rural residents is considered to bare a close relation with oral environments and other factors related to halitosis such as the Snyder test from caries activity test, and salivary flow rate test. For the prevention of halitosis of residents in rural areas, we have to focus on correct tooth brushing methods and tongue brushing, with using auxiliary oral hygiene devices to remove fur of tongue plaque and food impaction. Also, when the cause and ingredients of halitosis are diverse and complex, in order to analyze exactly the factors of individual halitosis development, we need continuous and systematic study in order to provide rural residents with programs of oral hygiene education and encourage the use of dental hygienists in public health centers.

A Study for Improvement of Nursing Service Administration (병원 간호행정 개선을 위한 연구)

  • 박정호
    • Journal of Korean Academy of Nursing
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    • v.3 no.1
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    • pp.13-40
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    • 1972
  • Much has teed changed in the field of hospital administration in the It wake of the rapid development of sciences, techniques ana systematic hospital management. However, we still have a long way to go in organization, in the quality of hospital employees and hospital equipment and facilities, and in financial support in order to achieve proper hospital management. The above factors greatly effect the ability of hospitals to fulfill their obligation in patient care and nursing services. The purpose of this study is to determine the optimal methods of standardization and quality nursing so as to improve present nursing services through investigations and analyses of various problems concerning nursing administration. This study has been undertaken during the six month period from October 1971 to March 1972. The 41 comprehensive hospitals have been selected iron amongst the 139 in the whole country. These have been categorized according-to the specific purposes of their establishment, such as 7 university hospitals, 18 national or public hospitals, 12 religious hospitals and 4 enterprise ones. The following conclusions have been acquired thus far from information obtained through interviews with nursing directors who are in charge of the nursing administration in each hospital, and further investigations concerning the purposes of establishment, the organization, personnel arrangements, working conditions, practices of service, and budgets of the nursing service department. 1. The nursing administration along with its activities in this country has been uncritical1y adopted from that of the developed countries. It is necessary for us to re-establish a new medical and nursing system which is adequate for our social environments through continuous study and research. 2. The survey shows that the 7 university hospitals were chiefly concerned with education, medical care and research; the 18 national or public hospitals with medical care, public health and charity work; the 2 religious hospitals with medical care, charity and missionary works; and the 4 enterprise hospitals with public health, medical care and charity works. In general, the main purposes of the hospitals were those of charity organizations in the pursuit of medical care, education and public benefits. 3. The survey shows that in general hospital facilities rate 64 per cent and medical care 60 per-cent against a 100 per cent optimum basis in accordance with the medical treatment law and approved criteria for training hospitals. In these respects, university hospitals have achieved the highest standards, followed by religious ones, enterprise ones, and national or public ones in that order. 4. The ages of nursing directors range from 30 to 50. The level of education achieved by most of the directors is that of graduation from a nursing technical high school and a three year nursing junior college; a very few have graduated from college or have taken graduate courses. 5. As for the career tenure of nurses in the hospitals: one-third of the nurses, or 38 per cent, have worked less than one year; those in the category of one year to two represent 24 pet cent. This means that a total of 62 per cent of the career nurses have been practicing their profession for less than two years. Career nurses with over 5 years experience number only 16 per cent: therefore the efficiency of nursing services has been rated very low. 6. As for the standard of education of the nurses: 62 per cent of them have taken a three year course of nursing in junior colleges, and 22 per cent in nursing technical high schools. College graduate nurses come up to only 15 per cent; and those with graduate course only 0.4 per cent. This indicates that most of the nurses are front nursing technical high schools and three year nursing junior colleges. Accordingly, it is advisable that nursing services be divided according to their functions, such as professional, technical nurses and nurse's aides. 7. The survey also shows that the purpose of nursing service administration in the hospitals has been regulated in writing in 74 per cent of the hospitals and not regulated in writing in 26 per cent of the hospitals. The general purposes of nursing are as follows: patient care, assistance in medical care and education. The main purpose of these nursing services is to establish proper operational and personnel management which focus on in-service education. 8. The nursing service departments belong to the medical departments in almost 60 per cent of the hospitals. Even though the nursing service department is formally separated, about 24 per cent of the hospitals regard it as a functional unit in the medical department. Only 5 per cent of the hospitals keep the department as a separate one. To the contrary, approximately 12 per cent of the hospitals have not established a nursing service department at all but surbodinate it to the other department. In this respect, it is required that a new hospital organization be made to acknowledge the independent function of the nursing department. In 76 per cent of the hospitals they have advisory committees under the nursing department, such as a dormitory self·regulating committee, an in-service education committee and a nursing procedure and policy committee. 9. Personnel arrangement and working conditions of nurses 1) The ratio of nurses to patients is as follows: In university hospitals, 1 to 2.9 for hospitalized patients and 1 to 4.0 for out-patients; in religious hospitals, 1 to 2.3 for hospitalized patients and 1 to 5.4 for out-patients. Grouped together this indicates that one nurse covers 2.2 hospitalized patients and 4.3 out-patients on a daily basis. The current medical treatment law stipulates that one nurse should care for 2.5 hospitalized patients or 30.0 out-patients. Therefore the statistics indicate that nursing services are being peformed with an insufficient number of nurses to cover out-patients. The current law concerns the minimum number of nurses and disregards the required number of nurses for operation rooms, recovery rooms, delivery rooms, new-born baby rooms, central supply rooms and emergency rooms. Accordingly, tile medical treatment law has been requested to be amended. 2) The ratio of doctors to nurses: In university hospitals, the ratio is 1 to 1.1; in national of public hospitals, 1 to 0.8; in religious hospitals 1 to 0.5; and in private hospitals 1 to 0.7. The average ratio is 1 to 0.8; generally the ideal ratio is 3 to 1. Since the number of doctors working in hospitals has been recently increasing, the nursing services have consequently teen overloaded, sacrificing the services to the patients. 3) The ratio of nurses to clerical staff is 1 to 0.4. However, the ideal ratio is 5 to 1, that is, 1 to 0.2. This means that clerical personnel far outnumber the nursing staff. 4) The ratio of nurses to nurse's-aides; The average 2.5 to 1 indicates that most of the nursing service are delegated to nurse's-aides owing to the shortage of registered nurses. This is the main cause of the deterioration in the quality of nursing services. It is a real problem in the guest for better nursing services that certain hospitals employ a disproportionate number of nurse's-aides in order to meet financial requirements. 5) As for the working conditions, most of hospitals employ a three-shift day with 8 hours of duty each. However, certain hospitals still use two shifts a day. 6) As for the working environment, most of the hospitals lack welfare and hygienic facilities. 7) The salary basis is the highest in the private university hospitals, with enterprise hospitals next and religious hospitals and national or public ones lowest. 8) Method of employment is made through paper screening, and further that the appointment of nurses is conditional upon the favorable opinion of the nursing directors. 9) The unemployment ratio for one year in 1971 averaged 29 per cent. The reasons for unemployment indicate that the highest is because of marriage up to 40 per cent, and next is because of overseas employment. This high unemployment ratio further causes the deterioration of efficiency in nursing services and supplementary activities. The hospital authorities concerned should take this matter into a jeep consideration in order to reduce unemployment. 10) The importance of in-service education is well recognized and established. 1% has been noted that on the-job nurses. training has been most active, with nursing directors taking charge of the orientation programs of newly employed nurses. However, it is most necessary that a comprehensive study be made of instructors, contents and methods of education with a separate section for in-service education. 10. Nursing services'activities 1) Division of services and job descriptions are urgently required. 81 per rent of the hospitals keep written regulations of services in accordance with nursing service manuals. 19 per cent of the hospitals do not keep written regulations. Most of hospitals delegate to the nursing directors or certain supervisors the power of stipulating service regulations. In 21 per cent of the total hospitals they have policy committees, standardization committees and advisory committees to proceed with the stipulation of regulations. 2) Approximately 81 per cent of the hospitals have service channels in which directors, supervisors, head nurses and staff nurses perform their appropriate services according to the service plans and make up the service reports. In approximately 19 per cent of the hospitals the staff perform their nursing services without utilizing the above channels. 3) In the performance of nursing services, a ward manual is considered the most important one to be utilized in about 32 percent of hospitals. 25 per cent of hospitals indicate they use a kardex; 17 per cent use ward-rounding, and others take advantage of work sheets or coordination with other departments through conferences. 4) In about 78 per cent of hospitals they have records which indicate the status of personnel, and in 22 per cent they have not. 5) It has been advised that morale among nurses may be increased, ensuring more efficient services, by their being able to exchange opinions and views with each other. 6) The satisfactory performance of nursing services rely on the following factors to the degree indicated: approximately 32 per cent to the systematic nursing activities and services; 27 per cent to the head nurses ability for nursing diagnosis; 22 per cent to an effective supervisory system; 16 per cent to the hospital facilities and proper supply, and 3 per cent to effective in·service education. This means that nurses, supervisors, head nurses and directors play the most important roles in the performance of nursing services. 11. About 87 per cent of the hospitals do not have separate budgets for their nursing departments, and only 13 per cent of the hospitals have separate budgets. It is recommended that the planning and execution of the nursing administration be delegated to the pertinent administrators in order to bring about improved proved performances and activities in nursing services.

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The 1998, 1999 Patterns of Care Study for Breast Irradiation after Mastectomy in Korea (1998, 1999년도 우리나라에서 시행된 근치적 유방 전절제술 후 방사선치료 현황 조사)

  • Keum,, Ki-Chang;Shim, Su-Jung;Lee, Ik-Jae;Park, Won;Lee, Sang-Wook;Shin, Hyun-Soo;Chung, Eun-Ji;Chie, Eui-Kyu;Kim, Il-Han;Oh, Do-Hoon;Ha, Sung-Whan;Lee, Hyung-Sik;Ahn, Sung-Ja
    • Radiation Oncology Journal
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    • v.25 no.1
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    • pp.7-15
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    • 2007
  • [ $\underline{Purpose}$ ]: To determine the patterns of evaluation and treatment in patients with breast cancer after mastectomy and treated with radiotherapy. A nationwide study was performed with the goal of improving radiotherapy treatment. $\underline{Materials\;and\;Methods}$: A web- based database system for the Korean Patterns of Care Study (PCS) for 6 common cancers was developed. Randomly selected records of 286 eligible patients treated between 1998 and 1999 from 17 hospitals were reviewed. $\underline{Results}$: The ages of the study patients ranged from 20 to 80 years (median age 44 years). The pathologic T stage by the AJCC was T1 in 9.7% of the cases, T2 in 59.2% of the cases, T3 in 25.6% of the cases, and T4 in 5.3% of the cases. For analysis of nodal involvement, N0 was 7.3%, N1 was 14%, N2 was 38.8%, and N3 was 38.5% of the cases. The AJCC stage was stage I in 0.7% of the cases, stage IIa in 3.8% of the cases, stage IIb in 9.8% of the cases, stage IIIa in 43% of the cases, stage IIIb in 2.8% of the cases, and IIIc in 38.5% of the cases. There were various sequences of chemotherapy and radiotherapy after mastectomy. Mastectomy and chemotherapy followed by radiotherapy was the most commonly performed sequence in 47% of the cases. Mastectomy, chemotherapy, and radiotherapy followed by additional chemotherapy was performed in 35% of the cases, and neoadjuvant chemoradiotherapy was performed in 12.5% of the cases. The radiotherapy volume was chest wall only in 5.6% of the cases. The volume was chest wall and supraclavicular fossa (SCL) in 20.3% of the cases; chest wall, SCL and internal mammary lymph node (IMN) in 27.6% of the cases; chest wall, SCL and posterior axillary lymph node in 25.9% of the cases; chest wall, SCL, IMN, and posterior axillary lymph node in 19.9% of the cases. Two patients received IMN only. The method of chest wall irradiation was tangential field in 57.3% of the cases and electron beam in 42% of the cases. A bolus for the chest wall was used in 54.8% of the tangential field cases and 52.5% of the electron beam cases. The radiation dose to the chest wall was $45{\sim}59.4\;Gy$ (median 50.4 Gy), to the SCL was $45{\sim}59.4\;Gy$ (median 50.4 Gy), and to the PAB was $4.8{\sim}38.8\;Gy$, (median 9 Gy) $\underline{Conclusion}$: Different and various treatment methods were used for radiotherapy of the breast cancer patients after mastectomy in each hospital. Most of treatment methods varied in the irradiation of the chest wall. A separate analysis for the details of radiotherapy planning also needs to be followed and the outcome of treatment is needed in order to evaluate the different processes.

A Study on Risk Parity Asset Allocation Model with XGBoos (XGBoost를 활용한 리스크패리티 자산배분 모형에 관한 연구)

  • Kim, Younghoon;Choi, HeungSik;Kim, SunWoong
    • Journal of Intelligence and Information Systems
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    • v.26 no.1
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    • pp.135-149
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    • 2020
  • Artificial intelligences are changing world. Financial market is also not an exception. Robo-Advisor is actively being developed, making up the weakness of traditional asset allocation methods and replacing the parts that are difficult for the traditional methods. It makes automated investment decisions with artificial intelligence algorithms and is used with various asset allocation models such as mean-variance model, Black-Litterman model and risk parity model. Risk parity model is a typical risk-based asset allocation model which is focused on the volatility of assets. It avoids investment risk structurally. So it has stability in the management of large size fund and it has been widely used in financial field. XGBoost model is a parallel tree-boosting method. It is an optimized gradient boosting model designed to be highly efficient and flexible. It not only makes billions of examples in limited memory environments but is also very fast to learn compared to traditional boosting methods. It is frequently used in various fields of data analysis and has a lot of advantages. So in this study, we propose a new asset allocation model that combines risk parity model and XGBoost machine learning model. This model uses XGBoost to predict the risk of assets and applies the predictive risk to the process of covariance estimation. There are estimated errors between the estimation period and the actual investment period because the optimized asset allocation model estimates the proportion of investments based on historical data. these estimated errors adversely affect the optimized portfolio performance. This study aims to improve the stability and portfolio performance of the model by predicting the volatility of the next investment period and reducing estimated errors of optimized asset allocation model. As a result, it narrows the gap between theory and practice and proposes a more advanced asset allocation model. In this study, we used the Korean stock market price data for a total of 17 years from 2003 to 2019 for the empirical test of the suggested model. The data sets are specifically composed of energy, finance, IT, industrial, material, telecommunication, utility, consumer, health care and staple sectors. We accumulated the value of prediction using moving-window method by 1,000 in-sample and 20 out-of-sample, so we produced a total of 154 rebalancing back-testing results. We analyzed portfolio performance in terms of cumulative rate of return and got a lot of sample data because of long period results. Comparing with traditional risk parity model, this experiment recorded improvements in both cumulative yield and reduction of estimated errors. The total cumulative return is 45.748%, about 5% higher than that of risk parity model and also the estimated errors are reduced in 9 out of 10 industry sectors. The reduction of estimated errors increases stability of the model and makes it easy to apply in practical investment. The results of the experiment showed improvement of portfolio performance by reducing the estimated errors of the optimized asset allocation model. Many financial models and asset allocation models are limited in practical investment because of the most fundamental question of whether the past characteristics of assets will continue into the future in the changing financial market. However, this study not only takes advantage of traditional asset allocation models, but also supplements the limitations of traditional methods and increases stability by predicting the risks of assets with the latest algorithm. There are various studies on parametric estimation methods to reduce the estimated errors in the portfolio optimization. We also suggested a new method to reduce estimated errors in optimized asset allocation model using machine learning. So this study is meaningful in that it proposes an advanced artificial intelligence asset allocation model for the fast-developing financial markets.

Energy expenditure measurement of various physical activity and correlation analysis of body weight and energy expenditure in elementary school children (일부 초등학생의 대표적 신체활동의 에너지소비량 측정 및 에너지소비량과 체중과의 상관성 분석)

  • Kim, Jae-Hee;Son, Hee-Ryoung;Choi, Jung-Sook;Kim, Eun-Kyung
    • Journal of Nutrition and Health
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    • v.48 no.2
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    • pp.180-191
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    • 2015
  • Purpose: There is a lack of data on the energy cost of children's everyday activities, adult values are often used as surrogates. In addition, the influence of body weight on the energy cost of activity when expressed as metabolic equivalents (METs) has not been vigorously explored. Methods: In this study 20 elementary school students 9~12 years of age completed 18 various physical activities while energy expenditure was measured continuously using a portable telemetry gas exchange system ($K_4b^2$, Cosmed, Rome, Italy). Results: The average age was 10.4 years and the average height and weight was 145.1 cm and 43.6 kg, respectively. Oxygen consumption ($VO_2$), energy expenditure and METs at the time of resting of the subjects were 5.41 mL/kg/min, 1.44 kcal/kg/h, and 1.5 METs, respectively. METs values by 18 physical activities were as follows: Homework and reading books (1.6 METs), playing game with a mobile phone or video while sitting (1.6 METs), watching TV while sitting on a comfortable chair (1.7 METs), playing video game or mobile phone game while standing (1.9 METs), sweeping a room with a broom (2.7 METs) and playing a board game (2.8 METs) belong to light intensity physical activities. By contrary, speedy walking and running were 6.6 and 6.7 METs, respectively, which belong to high intensity physical activities over 6.0 METs. When the effect of body weight on physical activity energy expenditure was determined, $R^2$ values increased with 0.116 (playing a game at sitting), 0.176 (climbing up and down stairs), 0.246 (slow walking), and 0.455 (running), which showed that higher activity intensity increased explanation power of body weight on METs value. Conclusion: This study is important for direct evaluation of energy expenditure by physical activities of children, and it could be used directly for revising and complementing the existing activity classification table to fit for children.

Clinical Characteristics and Adherence of Patients Who Were Prescribed Home Oxygen Therapy Due to Chronic Respiratory Failure in One University Hospital: Survey after National Health Insurance Coverage (한 대학병원에서 조사된 재택산소요법을 받고 있는 환자의 특성과 재택산소요법 처방에 대한 순응도: 건강보험급여전환 후 조사)

  • Koo, Ho-Seok;Song, Young Jin;Lee, Seung Heon;Lee, Young Min;Kim, Hyun Gook;Park, I-Nae;Jung, Hoon;Choi, Sang Bong;Lee, Sung-Soon;Hur, Jin-Won;Lee, Hyuk Pyo;Yum, Ho-Kee;Choi, Soo Jeon;Lee, Hyun-Kyung
    • Tuberculosis and Respiratory Diseases
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    • v.66 no.3
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    • pp.192-197
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    • 2009
  • Background: Despite the benefits of home oxygen therapy in patients suffering chronic respiratory failure, previous reports in Korea revealed lower compliance to oxygen therapy and a shorter time for oxygen use than expected. However, these papers were published before oxygen therapy was covered by the national insurance system. Therefore, this study examined whether there were some changes in compliance, using time and other clinical features of home oxygen therapy after insurance coverage. Methods: This study reviewed the medical records of patients prescribed home oxygen therapy in our hospital from November 1, 2006 to September 31, 2008. The patients were interviewed either in person or by telephone to obtain information related to oxygen therapy. Results: During study period, a total 105 patients started home oxygen therapy. The mean age was 69 and 60 (57%) were male. The mean oxygen partial pressure in the arterial blood was 54.5 mmHg and oxygen saturation was 86.3%. Primary diseases that caused hypoxemia were COPD (n=64), lung cancer (n=14), Tb destroyed lung (n=12) and others. After oxygen therapy, more than 50% of patients experienced relief of their subjective dyspnea. The mean daily use of oxygen was 9.8${\pm}$7.3 hours and oxygen was not used during activity outside of their home (mean time, 5.4${\pm}$3.7 hours). Twenty four patients (36%) stopped using oxygen voluntarily 7${\pm}$4.7 months after being prescribed oxygen and showed a less severe pulmonary and right heart function. The causes of stopping were subjective symptom relief (n=11), inconvenience (n=6) and others (7). Conclusion: The prescription of home oxygen has increased since national insurance started to cover home oxygen therapy. However, the mean time for using oxygen is still shorter than expected. During activity of outside their home, patients could not use oxygen due to the absence of portable oxygen. Overall, continuous education to change the misunderstandings about oxygen therapy, more economic support from national insurance and coverage for portable oxygen are needed to extend the oxygen use time and maintain oxygen usage.