• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.23-30
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• 2011

본 연구는 산업용 열교환기 및 상용 파이프의 최적 설계를 위하여 열교환기 내의 사각형 단면 파이프의 shear-thickening 비뉴톤 유체의 압력강하 및 대류 열전달률을 수치해석적으로 수행하였다. shear-thickening 유체의 구성 방정식은 기존의 비뉴톤 유체 멱법칙을 보완한 확장 멱법칙 모델을 채택하였다. 파이프 내의 압력강하를 의미하는 마찰계수와 확장 레이놀즈 수의 곱은 기존 연구의 비교자료와 비교할 때 뉴톤 유체 영역과 멱법칙 영역에서 각각 0.018% 및 0.06% 내에서 일치함을 보였고, 대류 열전달률을 의미하는 뉴셀트 수는 문헌치와 비교할 때 뉴톤 유체 영역과 멱법칙 영역에서 각각 0.025% 및 0.14% 내에서 일치함을 보였다. 비뉴톤 확장 멱법칙 유체 모델의 형태를 띠는 shear-thickening 유체를 열교환기 또는 상용파이프 내의 사각형 단면 파이프 내에서 사용하면 유동지수(n)에 따라서 뉴톤 유체보다 최대 160%의 압력강하를 증가시켰고 최대 14%의 대류 열전달 감소를 발생시킬 수 있었다.

• Journal of Preventive Medicine and Public Health
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• v.28 no.4 s.51
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• pp.783-794
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• 1995

This study was conducted to clarify the relationship of body fat percent with serum lipid level and blood pressure in adults. The study subjects were 472 men and 189 women who visited Multiphasic Health Screening Center of Yeungnam University Hospital in Taegu from May 20 to September 30, 1994. The relationship of serum lipid and blood pressure with BMI, Katsura index, atherogenic index, which calculated from the health screening data and body fat percent measured by impedance fat meter(model SIF-819) were analyzed. Three groups were classified as Group I (men : body fat Percent $\geq$ 20, women : body fat percent $\geq$ 25), Group II (men : 15 $\leq$ body fat percent< 20, women : 20 $\leq$ body fat percent< 25), Group III(men : body fat percent < 15, women body fat percent <20). In this study, Group I accounted for 3.2% in men, 3.7% in women. Weight was significantly different among three groups in both sexes(p<0.01) and height was not significantly different among three groups. In men, serum total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein, atherogenic index were significantly different(p<0.01). In women, serum total cholesterol and low density lipoprotein were significantly different(p<0.05) but there was no differences in triglyceride and high density lipoprotein among three groups. BMI and Katsura index were significantly different among three groups in both sexes(p<0.01). In men, body fat percent was positively correlated with weight, BMI, Katsura index, total cholesterol, triglyceride, low density lipoprotein, atherogenic index and systolic and diastolic blood pressures, and negatively correlated with high density lipoprotein. In women, body fat percent was positively correlated with age, height, weight, BMI, Katsura index, total cholesterol, triglyceride, low density lipoprotein and atherogenic index, and negatively correlated with high density lipoprotein. But there was no significant correlation between body fat percent and blood pressure in women. In multiple regression analysis for total cholesterol, fat percent, age and BMI were significant independent variables in men$(p<0.05,\;R^2=0.1286)$, and body fat percent and age in women$(p<0.05,\;R^2=0.3399)$. In case of LDL/HDL ratio, only BMI was a significant independent variable in menu$(p<0.01,\;R^2=0.0954)$, and body fat percent, age and BMI in women$(p<0.05,\;R^2=0.3164)$. In multiple regression analysis, age, low density lipoprotein and total cholesterol were significant independent variables on systolic blood pressure in men$(p<0.05,\;R^2=0.1297)$, age and total cholesterol in women$(p<0.05,\;R^2=0.1705)$. On diastolic blood pressure, only age was a significantly independent variable in men$(p<0.01,\;R^2=0.0972)$ and women$(p<0.01,\;R^2=0.1218)$. From the result of this study, it could concluded that body fat percent was significantly associated with other obesity indices and serum lipid, but had no significant association with blood pressure. To establish the relationship of body fat percent with blood pressure, further study which consider other variables that may have an effect on blood pressure should be performed.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.123-123
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• 2011

가뭄은 다른 기상재해들과 달리 특정한 기후현상에 의해 발생하는 사건이 아닌 장기간의 강우 부족으로 인한 물 부족으로부터 기인하며, 가뭄의 특성상 가뭄의 시작과 끝을 명확히 구분하기 힘들며, 심도를 결정짓는 것 또한 어려움이 있다. 이러한 가뭄의 특성을 파악하기 위한 연구는 계속되고 있으며, SPI(Standardized Precipitation Index), PDSI(Palmer Drought Severity Index), SWSI(Surface Water Supply Index), EDI(Effective Drought Index), CMI(Crop Moisture Index)등과 같은 가뭄의 특성을 잘 반영한 가뭄지수의 개발 또한 끊임없이 이어지고 있다. 하지만 이러한 가뭄지수들은 기상학적, 기후학적, 농업적, 수문학적등과 같은 분류에 의해 가뭄의 표현이 상이한 결과를 보여주며, 동일한 방법으로 산정된 가뭄평가지수라 하더라도 지역적인 적합성 정도에서 또한 차이를 보인다. 본 연구에서는 우리나라의 실제 가뭄의 발생사례를 바탕으로 각종 가뭄지수들의 적합도와 가뭄의 변동특성을 파악하고자 한다. 우리나라의 가뭄특성을 확인하기 위하여 보고서 등 각종 문헌과 신문기사를 통해 1973년부터 2009년까지 실제 가뭄발생 기록을 정량화하고 행정구역단위의 우리나라 전역에 공간분포로 표현하였다. 69개 기상관측소의 강수 및 기온 자료를 통해 기상청과(SPI, PDSI, PN, 강수량십분위) 동일한 방법으로 가뭄지수를 산정 후 마찬가지로 행정구역단위의 우리나라 전역에 확장하였으며, 이렇게 생성된 각종 가뭄지수 및 기후변수의 공간분포와 실제 가뭄발생사례의 공간분포를 비교 분석함으로서 각 가뭄지수 및 기후변수의 적합성을 평가하였다. 각 가뭄지수 및 기후변수의 적합성을 평가하기 위하여 ROC space 상의 검정통계량을 이용하였다. 분석결과 PN(Percent of Normal)이 실제 가뭄의 현상을 가장 잘 표현했으며, 강수량, SPI 3, 강수량 십분위 등이 높은 상관성을 보였다. 또한 SPI12, PDSI, PN, 강수량십분위 등이 행정구역에 따른 산포정도가 비교적 낮게 나타났다. 본 연구를 통해 우리나라 전 지역 가뭄의 시 공간적인 가뭄변동특성을 파악하고, 기존에 사용되고 있는 가뭄지수의 적합도 평가를 통해 우리나라 가뭄특성을 가장 잘 반영한 가뭄지수의 선정과 각종 기후특성을 잘 반영하는 좀 더 향상된 가뭄지수 개발에 도움을 줄 수 있으며, 가뭄의 시 공간적인 예측에 대해 적합한 가뭄지수 선택에 도움을 줄 것으로 판단된다.

• Tuberculosis and Respiratory Diseases
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• v.39 no.5
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• pp.392-399
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• 1992

Background: Despite dyspnea is a predominant complaint of patients with respiratory disease, the mechanisms contributing to the sensation of breathlessness are poorly understood. Traditionally, physicians have measured objective pulmonary function to assess severity of dyspnea. But it will be also useful to measure subjective dyspnea index because dyspnea probably depends on a complex interplay of mechanical, experimental, emotional and other factors. Method: We measured breathlessness at rest, after Methacholine challenge and then bronchodilator inhalation using a Visual Analogue Scale (VAS) and Borg Scale Dyspnea Index (BSDI) in stable asthmatic patients. Spirometry was performed concomittently. Results: There was no correlation between dyspnea index and FEV1. There was also no correlation between the change in dyspnea index and change in FEV1. The change in dyspnea index after methacholine and bronchodilator was greater in clinically mild asthmatic patients than clinically severe symptomatic group. Conclusion: In asthmatic patients, there was a wide variation in sensory response for any given FEV1, and the change in perception of dyspnea was greater in those with clinically mild symptoms. The measurement of dyspnea index may yield information complementary to that obtained by spirometry.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.277-286
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• 2015

This study calculated the NDVI and the NDBI of the land-use change in major cities at North Korea through Landsat imagery, and analyzed the spatiality(LISA) with difference discretization of the UI index. As a result of the research, we could identify that the degree of urbanization has been increased in both Gaesung and Pyeongyang, but showed opposite spatial tendency to each other. The urban index of Pyeongyang, a nucleus district of North Korea, has been progressed quicker than Gaesung since 1994, while the urbanization development was being progressed also in general, as it expanded from the existing downtown area. On the other hand, the urbanization took place intensively at one region in Gaesung by developing the vegetation area that forest transfers into a built-up area, which has been judged from the great dynamic range of NDVI values. In conclusion, it is possible to extract necessary data for understanding the degree of urbanization and spatial characteristics of North Korea through the UI and the LISA analysis that are considered to propose useful methodology in investigating changes in North Korean cities and political levearage.

• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.1-8
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• 2019

This paper carried out a study to reduce damage from jellyfish whose population has increased due to global warming. The emergence of jellyfish on the beach could result in casualties from jellyfish stings and economic losses from closures. This paper confirmed from the preceding studies that the pattern of jellyfish's appearance is predictable through machine learning. This paper is an extension of The prediction model of emergence of Busan coastal jellyfish using SVM. In this paper, we used deep neural network to expand from the existing methods of predicting the existence of jellyfish to the classification by index. Due to the limitations of the small amount of data collected, the 84.57% prediction accuracy limit was sought to be resolved through data expansion using bootstraping. The expanded data showed about 7% higher performance than the original data, and about 6% better performance compared to the transfer learning. Finally, we used the test data to confirm the prediction performance of jellyfish appearance. As a result, although it has been confirmed that jellyfish emergence binary classification can be predicted with high accuracy, predictions through indexation have not produced meaningful results.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.57-71
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• 2002

We introduce three types of exponential survival models, such as simple model, change-point model and finite mixture model in this paper. Among these models, in order to choose the best model, the model choice method is proposed using Gelfand and Ghosh(1998)'s idea. Then to avoid the computational difficulties, data augmentation method (Tanner and Wong, 1987) and Gibbs sampler (Gelfand and Smith, 1990) are employed. Our methodology is applied to both simulated data and Stangl (1991)'s On-impramint Hydrochloride data.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.125-131
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• 2009

The aim of this study is to quantify the severity of flash food for a study watershed in Korea by estimation of flash food index using flood runoff hydrograph following Bhaskar et. al (2000). As an extension of the previous research, we examine the relation between flash food index and rainfall intensity, rainfall duration, and total runoff, respectively. This study has estimated the flash food index through simulated flood hydrographs to investigate the relative severity of flash flood in an ungauged basin, Megok river basin for 31 flood events.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.7 no.2
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• pp.19-26
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• 1997

In this paper, we propose an RSA multisignature scheme with no bit expansion in which the signing order is not restricted. In this scheme we use RSA moduli with the same bit length. the most 1 bits of which are same. The proposed scheme is based on these RSA moduli and a repeated exponentiation of Levine and Brawley. Kiesler and Harn first utilize the repeated exponentiation technique in their multisignature scheme, which requires 1.5m exponentiations for signing, where m is the number of signers. However, the proposed scheme requires (equation omitted) m exponentiation. So if l is sufficiently large (l $\geq$ 32), then we can neglect the vaue (equation omitted

• Journal of Korea Water Resources Association
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• v.50 no.7
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• pp.441-453
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• 2017

Water distribution networks (WDNs) supply drinking water to end users by maintaining sufficient water pressure for reliable water supply in normal and abnormal conditions. To design and operate WDNs in efficient way, it is required to quantify water supply ability of the network. Various reliability indices have been developed and applied in this field. Most of the reliability indices are calculated based on the energy within a network; that is, the total energy entered the network, the energy dissipated through water supply process, and the energy finally supplied at the nodes, etc. This study explains the energy composition in WDNs and introduces three well-known reliability indices developed based on the energy composition of the network. The three indices were applied to a study network under various demand loading scenarios that could occur in real-life operation practices. This study aimed to investigate the applicability of the reliability indices under abnormal scenarios and proposed to illustrate the spatial distribution of the system reliability in more intuitive way for proper responses to the abnormal situations.