• 제목/요약/키워드: linear system model

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Analysis of Resistance Performance of a Ship having a Large Attitude based on CFD (CFD에 의한 자세변화가 큰 선박의 저항성능 해석)

  • Kim, Hyun-Soo;Park, Dong-Woo;Yang, Young-Jun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.7
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    • pp.961-967
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    • 2019
  • This research presents an efficient method based on computational fluid dynamics (CFD) for estimating the resistance performance of a ship with a large settlement amount and a dynamic trim. The settlement of the inviscid flow analysis and the results of dynamic trim were used to set a large attitude for the ship prior to performing a viscous flow analysis; a viscous flow analysis was subsequently performed by Dynamic Fluid Body Interaction (DFBI). This method is termed as method I, in which a simple grating system can be used without employing the overset mesh technique by setting many attitudes before interpretation. Thus, method I is advantageous in reducing calculation time and improving calculation accuracy. The viscous flow analysis was performed using a commercial CFD code STAR-CCM+. Compared with the final convergence result, the first viscous flow analysis result of method I exhibited a variation of less than 1 % of resistance. The result was obtained by changing the gratings each time an attitude is changed at each calculation stage, based on the DFBI method provided to STAR-CCM+ using a simple grating system, which is not a superposed grating. This method is termed as method II. Compared with method II of resistance, method I exhibited a dif erence of 0.03-0.6 % for linear velocity. The results of method I were confirmed to be qualitatively and quantitatively appropriate through comparison with several trillion simulations.

Development of Ankle Power Assistive Robot using Pneumatic Muscle (공압근육을 사용한 발목근력보조로봇의 개발)

  • Kim, Chang-Soon;Kim, Jung-Yup
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.8
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    • pp.771-782
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    • 2017
  • This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.

A Method for Estimating the Lung Clinical Target Volume DVH from IMRT with and without Respiratory Gating

  • J. H. Kung;P. Zygmanski;Park, N.;G. T. Y. Chen
    • Proceedings of the Korean Society of Medical Physics Conference
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    • 2002.09a
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    • pp.53-60
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    • 2002
  • Motion of lung tumors from respiration has been reported in the literature to be as large as of 1-2 cm. This motion requires an additional margin between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV). While such a margin is necessary, it may not be sufficient to ensure proper delivery of Intensity Modulated Radiotherapy (IMRT) to the CTV during the simultaneous movement of the DMLC. Gated treatment has been proposed to improve normal tissues sparing as well as to ensure accurate dose coverage of the tumor volume. The following questions have not been addressed in the literature: a) what is the dose error to a target volume without gated IMRT treatment\ulcorner b) what is an acceptable gating window for such treatment. In this study, we address these questions by proposing a novel technique for calculating the 3D dose error that would result if a lung IMRT plan were delivered without gating. The method is also generalized for gated treatment with an arbitrary triggering window. IMRT plans for three patients with lung tumor were studied. The treatment plans were generated with HELIOS for delivery with 6 MV on a CL2100 Varian linear accelerator with a 26 pair MLC. A CTV to PTV margin of 1 cm was used. An IMRT planning system searches for an optimized fluence map ${\Phi}$ (x,y) for each port, which is then converted into a dynamic MLC file (DMLC). The DMLC file contains information about MLC subfield shapes and the fractional Monitor Units (MUs) to be delivered for each subfield. With a lung tumor, a CTV that executes a quasi periodic motion z(t) does not receive ${\Phi}$ (x,y), but rather an Effective Incident Fluence EIF(x,y). We numerically evaluate the EIF(x,y) from a given DMLC file by a coordinate transformation to the Target's Eye View (TEV). In the TEV coordinate system, the CTV itself is stationary, and the MLC is seen to execute a motion -z(t) that is superimposed on the DMLC motion. The resulting EIF(x,y)is inputted back into the dose calculation engine to estimate the 3D dose to a moving CTV. In this study, we model respiratory motion as a sinusoidal function with an amplitude of 10 mm in the superior-inferior direction, a period of 5 seconds, and an initial phase of zero.

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Analysis on the Effect of the Urban Park Development on Change of Urban Spatial Structures - Focused on Gentrification around Seoul Forestry Park in Seongdong-gu - (도시공원 조성이 도시공간구조 변화에 미치는 영향 분석 - 성동구 서울숲 젠트리피케이션 현상을 중심으로 -)

  • Moon, Seung-Woon;Kim, Euijune;Ku, Jin-Hyuk
    • Journal of the Korean Institute of Landscape Architecture
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    • v.45 no.2
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    • pp.76-88
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    • 2017
  • The urban park plays important roles in protecting the urban landscape and improving citizens' health, recreation, and the emotional life. Above and beyond these roles, the urban park is expected to rearrange urban spatial structures as a kind of urban system. The purpose of this paper is to identify empirically to change urban spatial structures by construction of the urban park. This study regards gentrification around the urban park as a process to change urban spatial structures. The gentrification means the regeneration and upgrading of deteriorated urban property by the middle class or commercial developers. The site of case analysis is the Seoul Forestry Park in Sungdong-gu, Seoul. The Seoul Forestry Park is regarded as a representative urban park of Seoul, and caused gentrification around park after the 2005 opening. This study operationally defines the gentrification index and the accessibility index from an urban park and offers an empirical analysis of relation among the urban park, the gentrification and urban spatial structure in a statistic district which is the minimum unit of Korean statistic data in 2000, 2005, and 2010, using Difference-in-Difference method and linear probability model. The results of this empirical study show that the Seoul Forestry Park changes urban spatial structures by gentrification. It reverses a trend of migration of gentrifiers before and after construction of the Seoul Forestry Park. It suggests urban park construction as an alternative method for urban regeneration by inducing the middle class into the inner city of Seoul.

The Impact of Care Workers' Employment Characteristics and Perception of Facility Directors' Transformational Leadership on Quality of Service (요양보호사의 고용특성과 시설장에 대한 변혁적 리더십 인식이 서비스 질에 미치는 영향에 관한 연구)

  • Kim, Hye Ji;Park, Sang Hee;Kim, Bum Jung
    • 한국노년학
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    • v.41 no.2
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    • pp.217-240
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    • 2021
  • The purpose of this study is to examine the effect of care workers' employment characteristics and perception of facility directors' transformational leadership on quality of service through a hierarchical linear model. For this aim, survey data were collected amongst 240 older adults and 200 care workers who are affiliated within 45 long-term care facilities in Seoul, and analyzed using SPSS 26.0 and HLM 8.0. As a result, one's perception of transformational leadership had a positive effect, whereas, among employment characteristics, employment type and working hours had negative effects on quality of service. Regular workers with fewer working hours and higher awareness of transformational leadership toward the director provided higher quality of service. But wage, total experience and tenure didn't meaningfully affect it. Therefore, the following suggestions were presented. First, it is necessary to reorganize incentive, salary systems and budgets, changing the status of temporary workers' hourly wage system into that of regular workers' monthly one in order to strengthen employment security with acknowledging fundamental professional values through reinforcement of expertise. Reinforcement of long-term care's publicness and establishment of base facilities are also suggested. Second, maintaining appropriate hours of work and rest including annual leave under the Labor Standards Act is needed. Also, increasing the salary of and decreasing working hours for night shift workers are required. Third, education and intervention for inspiring transformational leadership of directors and strengthening qualification standards of them are required.

The Adaptive Personalization Method According to Users Purchasing Index : Application to Beverage Purchasing Predictions (고객별 구매빈도에 동적으로 적응하는 개인화 시스템 : 음료수 구매 예측에의 적용)

  • Park, Yoon-Joo
    • Journal of Intelligence and Information Systems
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    • v.17 no.4
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    • pp.95-108
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    • 2011
  • TThis is a study of the personalization method that intelligently adapts the level of clustering considering purchasing index of a customer. In the e-biz era, many companies gather customers' demographic and transactional information such as age, gender, purchasing date and product category. They use this information to predict customer's preferences or purchasing patterns so that they can provide more customized services to their customers. The previous Customer-Segmentation method provides customized services for each customer group. This method clusters a whole customer set into different groups based on their similarity and builds predictive models for the resulting groups. Thus, it can manage the number of predictive models and also provide more data for the customers who do not have enough data to build a good predictive model by using the data of other similar customers. However, this method often fails to provide highly personalized services to each customer, which is especially important to VIP customers. Furthermore, it clusters the customers who already have a considerable amount of data as well as the customers who only have small amount of data, which causes to increase computational cost unnecessarily without significant performance improvement. The other conventional method called 1-to-1 method provides more customized services than the Customer-Segmentation method for each individual customer since the predictive model are built using only the data for the individual customer. This method not only provides highly personalized services but also builds a relatively simple and less costly model that satisfies with each customer. However, the 1-to-1 method has a limitation that it does not produce a good predictive model when a customer has only a few numbers of data. In other words, if a customer has insufficient number of transactional data then the performance rate of this method deteriorate. In order to overcome the limitations of these two conventional methods, we suggested the new method called Intelligent Customer Segmentation method that provides adaptive personalized services according to the customer's purchasing index. The suggested method clusters customers according to their purchasing index, so that the prediction for the less purchasing customers are based on the data in more intensively clustered groups, and for the VIP customers, who already have a considerable amount of data, clustered to a much lesser extent or not clustered at all. The main idea of this method is that applying clustering technique when the number of transactional data of the target customer is less than the predefined criterion data size. In order to find this criterion number, we suggest the algorithm called sliding window correlation analysis in this study. The algorithm purposes to find the transactional data size that the performance of the 1-to-1 method is radically decreased due to the data sparity. After finding this criterion data size, we apply the conventional 1-to-1 method for the customers who have more data than the criterion and apply clustering technique who have less than this amount until they can use at least the predefined criterion amount of data for model building processes. We apply the two conventional methods and the newly suggested method to Neilsen's beverage purchasing data to predict the purchasing amounts of the customers and the purchasing categories. We use two data mining techniques (Support Vector Machine and Linear Regression) and two types of performance measures (MAE and RMSE) in order to predict two dependent variables as aforementioned. The results show that the suggested Intelligent Customer Segmentation method can outperform the conventional 1-to-1 method in many cases and produces the same level of performances compare with the Customer-Segmentation method spending much less computational cost.

Application of Support Vector Regression for Improving the Performance of the Emotion Prediction Model (감정예측모형의 성과개선을 위한 Support Vector Regression 응용)

  • Kim, Seongjin;Ryoo, Eunchung;Jung, Min Kyu;Kim, Jae Kyeong;Ahn, Hyunchul
    • Journal of Intelligence and Information Systems
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    • v.18 no.3
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    • pp.185-202
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    • 2012
  • .Since the value of information has been realized in the information society, the usage and collection of information has become important. A facial expression that contains thousands of information as an artistic painting can be described in thousands of words. Followed by the idea, there has recently been a number of attempts to provide customers and companies with an intelligent service, which enables the perception of human emotions through one's facial expressions. For example, MIT Media Lab, the leading organization in this research area, has developed the human emotion prediction model, and has applied their studies to the commercial business. In the academic area, a number of the conventional methods such as Multiple Regression Analysis (MRA) or Artificial Neural Networks (ANN) have been applied to predict human emotion in prior studies. However, MRA is generally criticized because of its low prediction accuracy. This is inevitable since MRA can only explain the linear relationship between the dependent variables and the independent variable. To mitigate the limitations of MRA, some studies like Jung and Kim (2012) have used ANN as the alternative, and they reported that ANN generated more accurate prediction than the statistical methods like MRA. However, it has also been criticized due to over fitting and the difficulty of the network design (e.g. setting the number of the layers and the number of the nodes in the hidden layers). Under this background, we propose a novel model using Support Vector Regression (SVR) in order to increase the prediction accuracy. SVR is an extensive version of Support Vector Machine (SVM) designated to solve the regression problems. The model produced by SVR only depends on a subset of the training data, because the cost function for building the model ignores any training data that is close (within a threshold ${\varepsilon}$) to the model prediction. Using SVR, we tried to build a model that can measure the level of arousal and valence from the facial features. To validate the usefulness of the proposed model, we collected the data of facial reactions when providing appropriate visual stimulating contents, and extracted the features from the data. Next, the steps of the preprocessing were taken to choose statistically significant variables. In total, 297 cases were used for the experiment. As the comparative models, we also applied MRA and ANN to the same data set. For SVR, we adopted '${\varepsilon}$-insensitive loss function', and 'grid search' technique to find the optimal values of the parameters like C, d, ${\sigma}^2$, and ${\varepsilon}$. In the case of ANN, we adopted a standard three-layer backpropagation network, which has a single hidden layer. The learning rate and momentum rate of ANN were set to 10%, and we used sigmoid function as the transfer function of hidden and output nodes. We performed the experiments repeatedly by varying the number of nodes in the hidden layer to n/2, n, 3n/2, and 2n, where n is the number of the input variables. The stopping condition for ANN was set to 50,000 learning events. And, we used MAE (Mean Absolute Error) as the measure for performance comparison. From the experiment, we found that SVR achieved the highest prediction accuracy for the hold-out data set compared to MRA and ANN. Regardless of the target variables (the level of arousal, or the level of positive / negative valence), SVR showed the best performance for the hold-out data set. ANN also outperformed MRA, however, it showed the considerably lower prediction accuracy than SVR for both target variables. The findings of our research are expected to be useful to the researchers or practitioners who are willing to build the models for recognizing human emotions.

A Preliminary Study for Expending of Hospital-Based Horne Health Care Coverage - Focused on Accident Inpatients Who has the Workers Compensation Insurance - (병원중심 가정간호사업 관리대상범위 확대를 위한 기초연구)

  • Lee, Sook-Ja;Lee, Jin-Kyung;Ryu, Ho-Sihn
    • Journal of Korean Academic Society of Home Health Care Nursing
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    • v.6
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    • pp.5-18
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    • 1999
  • This study was attempt to encourage for developing on rehabilitation delivery system and programs as a substitute service instead of hospitalization for accident patients at work, such as hospital based home health care nursing service. It needs vary substitutes service of hospitalization to curtail the length of stay for inpatients who were hospitalized with workers compensation insurance. It focused on developing an estimation of early discharge day of accident inpatients based on a detail statement of treatment for 115 inpatients who were hospitalized at General Hospital in 1997. This study has four specific purpose as follows. First, to find out the status of health service utilization. Second, to estimate the early discharge days and income increasing effect based on the early discharge for those patients. Third, to identify the factors to affect total medical expenditure and the length of stay for those inpatients. Forth, to figure out the need of utilizing home health care nursing service for accident patients. In order to analyze of the length of stay and medical expenditure for inpatients who were hospitalized due to the accident, the authors conducted with micro-analysis and macroanalysis from medical records and medical expenditure records. Micro-analysis was done by nominal group discussion of 4 expertise with the critical criteria. such as a decrease in the amount of treatment after surgery, treatments, tests, drugs and changes in the tests consistency, drug methods, vital signs, start of ROM exercise, doctor's order, patient's outside visiting ability, stable conditions. In addition to identify affected variables for medical expenditure. the length of stay and income effect due to early discharge day, the data was analyzed with multiple regression analysis and linear regression analysis model by SPSS-PC for windows and Excell program. Results of this study as follows. First, the mean length of stay was 37.1 days, whereas the mean length of stay due to early discharge was 28.2 days at the hospital. The estimation of early discharge days were shown that depends on the length of stay. The longer length of stay, the longer length of early discharge days, such as under 7 days length of stay patients was to estimated the mean length of stay was 4.9 days and early discharge days was 4.6. whereas the mean length of stay was 122.6 days and early discharge days was 92.0 respectively. The mean medical expenditure per day were found to be 133.409 Won. whereas the mean medical expenditure per day was shown negative linear trends according to the length of stay at the hospital. The estimation results of the income effect due to 11 early discharge days per bed was around 2,150,000 won. However, it means not the real benefits from early discharge, but the income increasing amount without considering medical prime cost in general hospital. Therefore, it needs further analysis on the cost containments and benefits under the considering as well turn over rates per bed as the medical prime costs. The length of stay was most significant and the sign was positive to the total medical expenditure, as expected. Surgery and patient's residential area also an important variable in explaining medical expenditure. The level of complications was most significant variable in explaining the length of stay. The level of the needs on horne health care nursing service which can be used for early discharge accident patients were shown very high. The needs distribution varied from 65.5% of patients and 88.9% of caregivers, to 96.4% of doctors, and 99.1% of nurses. In addition horne health nurse responded that they can be managed the accident inpatients from early discharge. From these research findings. the following suggestions has been drawn it needs to develop strategies on rehabilitation delivery system in order to focused on consumer's side which is planned for 21 century health policy in Korea. Vary intermediate facilities and horne health care would have been developed in the community based for comprehensive rehabilitation services as a substitutes of hospitalization for shortening the length of stay of hospitalizations. In hospital based horne health care nursing service, it's available immediately to utilize for the patients who wanted rehabilitation services as a substitutes of hospitalization under the cooperations with workers compensation insurance company.

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Fertility Evaluation of Upland Fields by Combination of Landscape and Soil Survey Data with Chemical Properties in Soil (토양 화학성과 지형 및 토양 조사자료를 활용한 밭 토양의 비옥도 평가)

  • Hong, Soon-Dal;Kim, Jai-Joung;Min, Kyong-Beum;Kang, Bo-Goo;Kim, Hyun-Ju
    • Korean Journal of Soil Science and Fertilizer
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    • v.33 no.4
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    • pp.221-233
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    • 2000
  • Evaluation method of soil fertility by application of geographic information system (GIS) which includes landscape characteristics and soil map data was investigated from productivities of red pepper and tobacco grown on the fields with no fertilization. Total 131 fields experiments, 64 fields of red pepper and 67 fields of tobacco were conducted from 22 and 23 fields for red pepper and tobacco, respectively, located at Cheangweon and Eumseong counties in 1996, from 20 and 25 fields at Boeun and Goesan counties in 1997, and 22 and 19 fields at Jincheon and Chungju counties in 1998. All the experimental sites were selected on the basis of wide range of distribution in landscape and soil attributes. Dry weights and nutrients (N, P and K) uptakes by red pepper plant and tobacco leaves were considered as basic fertility of the soil (BFS). The BFS was estimated by twenty-five independent variables including 13 chemical properties and 12 GIS data. Twenty-five independent variables were classified by two groups, 15 quantitative variables and 10 qualitative variables, and were analyzed by multiple linear regression (MLR) of REG and GLM models of SAS. Dry weight of red pepper (DWRP) and dry weight of tobacco leaves (DWTL) every year showed high variations by five times in difference plots with minimum yield and maximum yield indicating the diverse soil fertility among the experimental fields. Evaluation for the BFS by the MLR including independent variables was better than that by simple regression showing gradual improvement by adding chemical properties, quantitative variables, and qualitative variables of the GIS. However the evaluation for the BFS by the MLR showed the better result for tobacco than red pepper. For example the variability in the DWTL by MLR was explained 34.2% by only chemical properties, 35.0% by adding quantitative variables, and 72.5% by adding both the quantitative and qualitative variables of the GIS compared with 21.7% by simple regression with $NO_3-N$ content in soil. Consequently, it is assumed that this approach by the MLR including both the quantitative and qualitative variables was available as an evaluation model of soil fertility for upland field.

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A Preliminary Study for Expending of Hospital-Based Home Health Care Coverage - Focused on Car Accident Inpatients Who has the Compensation Insurance - (병원중심 가정간호관리대상 범위 확대를 위한 기초연구(II) - 자동차보험가입 입원환자를 대상으로 -)

  • Park, Eun-Sook;Lee, Sook-Ja;Park, Young-Ju;Ryu, Ho-Sihn
    • Journal of Korean Academic Society of Home Health Care Nursing
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    • v.7 no.1
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    • pp.58-72
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    • 2000
  • This study was an attempt to encourage the development of a rehabilitation delivery system and programs as a substitute service for hospitalization on the case of car accident patients, such as hospital based home health care nursing services. Various substitute services for hospitalization are required to curtail the length of stay for inpatients who were hospitalized with car accident compensation insurance. It focused on developing an estimation an early discharge day for car accident inpatients based on detailed statements of treatment for 111 inpatients who were hospitalized at the General Hospital in 1997. This study had four specific purposes as follows. First. to find out the utilization of medical services. Second, to estimate the time of early discharge and income increasing effect based on early discharge for those patients. Third, to identify the factors affecting total medical expenditure and the length of stay for those inpatients. Forth, to figure out the need of utilizing home health care nursing service for accident patients. In order to analyze the length of stay and medical expenditure for inpatients who were hospitalized due to car accidents, the authors conducted micro- and macro-analysis of medical and medical expenditure records. Micro-analysis was done by nominal group discussion of 4 expertise with the critical criteria, such as a decrease in the amount of treatment after surgery, treatments, tests, drugs and changes in the test consistency, drug methods, vital signs, start of ROM exercise, doctor's order, patient's outside visiting ability, and stable conditions. In addition to identifying variables affecting medical expenditure, and the length of stay and income effect due to early discharge day, the data was analyzed with a multiple regression analysis and linear regression analysis model by SPSS-PC for windows and Excell program. Results of this study were as follows. First. the mean length of stay was 50.3 days. whereas the mean length of stay due to early discharge was 34.3 days at the hospital. The estimation of time of early discharge depended on the length of stay. The longer the length of stay, the longer the length of time of early discharge : for instance a length of stay under 10 days was estimated as correlating to a mean length of stay of 6.6 days and early discharge of 6.5. The mean length of stay was 217.4 days and the time of early discharge was 110.1 respectively. The mean medical expenditure per day was found to be 169.085 Won and the mean medical expenditure per day showed negative linear trends according to the length of stay at the hospital. The estimation results of the income effect due to being discharged 16 days early was around 2,244,000 won per bed. However. this sum does not represent the real benefits resulting from early discharge, but rather the income increasing amount without considering medical prime cost in the general hospital. Therefore, further analysis is required on the cost containments and benefits as turn over rate per bed as the medical prime costs. The length of stay was most significant and was positive to the total medical expenditure, as expected. Surgery and patient's residential area was also an important variable in explaining medical expenditure. The level of complications was the most significant variable in explaining the length of stay. There was a high level for need a home health care nursing service which further supports early discharge for accident patients. In addition, when the patient was discharged. they needed follow up care for complications suffered during the car accident. $86.8\%$ of discharged patients responded that they needed home health services after early discharge. From these research findings, the following suggestions have been drawn. Strategies on a health care delivery system must be developed in order to focus on the consumer's needs and being planned for 21 century health policy in Korea. Community based intermediate facilities or home health care should be developed for rehabilitation services as a substitute for hospitalization in order to shorten the length of stay would be. A hospital based home health care nursing service. it would be available immediately to utilize by patients who want rehabilitation services as a substitute for hospitalization with the cooperation of car insurance companies.

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