• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.381-381
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• 2018

우리나라에서는 지속적인 자연재해로 각기 다른 필요성과 목적에 따라 다양한 형태의 홍수 침수 관련 지도가 작성되어 왔다. 연구 성과로 작성된 계획 빈도 및 상위 2개 빈도의 호우피해예상도를 실측 강우와 연계하여 재난관리단계별 대응단계에 활용하기 위해 실시간 피해위험구역을 표출하고자 한다. 본 연구는 실시간으로 피해위험구역을 표출하기 위해 실측 강우와 연계된 호우피해예상도에 공간 보간 알고리즘을 적용하고자 한다. 호우피해예상도란 돌발호우나 태풍으로 인하여 홍수가 발생하면 인명 및 재산피해를 최소화하기 위해 홍수지역을 미리 예측 가능하도록 제작된 지도이다. 지형자료(DEM), 하천 중심선(Stream Centerline), 하천 횡단면(Cross-Section Line), 제방고(Bank), 수문기상 자료(Hydrological Data), 조도계수(Roughness) 등을 사용하여 하천법 제 21조와 하천법시행령 제 17조를 근거로 작성된다. 본 연구에서는 호우피해예상도에 IDW(Inverse Distance Weighted, 역거리가중법) 보간, TIN(Triangulated Irregular Network system, 불규칙삼각망) 보간, Kriging 보간 방법 적용 알고리즘을 제시하고자 하였다. 호우피해예상도에 보간 알고리즘을 적용하기 위해 보간 방법에 따른 적용사례를 분석하였으며 그 결과, 보간 알고리즘을 적용한 호우피해예상도 보간을 통하여 계획빈도 및 상위 2개 빈도 이외의 빈도(하위빈도-계획빈도, 계획빈도-상위빈도 구간)에 대한 호우피해예상도의 피해위험구역 구현 방안을 제시하였다. 호우피해예상도에 IDW, TIN, Kriging 보간 알고리즘을 적용하여 계획빈도 및 상위빈도 이외의 빈도에 대한 피해위험구역을 표출 할 수 있다. 표출된 계획빈도 및 상위빈도 이외의 빈도를 지점확률강우량-빈도에 대한 Matching table을 통하여 실측 강우와 연계 가능하다. 본 연구 결과는 추후 풍수해피해예측시스템에 활용하여 재난관리단계별 예방 및 대응 단계에 활용 할 수 있을 것으로 판단된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.109-114
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• 2008

This paper presents the development status of a subscale precooled turbojet engine "S-engine" for the hypersonic cruiser and space place. S-engine employs the precooled-cycle using liquid hydrogen as fuel and coolant. It has $23cm{\times}23cm$ of rectangular cross section, 2.6 m of the overall length and about 100 kg of the target weight employing composite materials for a variable-geometry rectangular air-intake and nozzle. The design thrust and specific impulse at sea-level-static(SLS) are 1.2 kN and 2,000 sec respectively. After the system design and component tests, a prototype engine made of metal was manufactured and provided for the system firing test using gaseous hydrogen in March 2007. The core engine performance could be verified in this test. The second firing test using liquid hydrogen was conducted in October 2007. The engine, fuel supplying system and control system for the next flight test were used in this test. We verified the engine start-up sequence, compressor-turbine matching and performance of system and components. A flight test of S-engine is to be conducted by the Balloon-based Operation Vehicle(BOV) at Taiki town in Hokkaido in October 2008. The vehicle is about 5 m in length, 0.55 m in diameter and 500 kg in weight. The vehicle is dropped from an altitude of 40 km by a high-altitude observation balloon. After 40 second free-fall, the vehicle pulls up and S-engine operates for 60 seconds up to Mach 2. High altitude tests of the engine components corresponding to the BOV flight condition are also conducted.

• 대한이식학회지
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• 제32권4호
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• pp.108-112
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• 2018

Antibody-mediated rejection (AMR) is a major complication after ABO-incompatible liver transplantation. According to the 2016 Banff Working Group on Liver Allograft Criteria for the diagnosis of acute AMR, a positive serum donor specific antibody (DSA) is needed. On the other hand, the clinical significance of the histological findings of AMR in the absence of DSA is unclear. This paper describes a 57-year-old man (blood type, O+) who suffered from hepatitis B virus cirrhosis with hepatocellular carcinoma. Pre-operative DSA and cross-matching were negative. After transplantation, despite the improvement of the liver function, acute AMR was observed in the protocol biopsy on postoperative day 7; the cluster of differentiation 19+ (CD19+) count was 0% and anti-ABO antibody titers were 1:2. This paper presents the allograft injury like AMR in the absence of DSA after ABOi living donor liver transplantation with low titers of anti-ABO antibody and depleted serum CD19+ B cells.

• 한국융합학회논문지
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• 제10권9호
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• pp.23-29
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• 2019

본 연구에서는 영상의 분위기를 심층 합성곱 신경망을 통해 8 가지로 분류하고, 이에 맞는 배경 음악을 적용하여 동영상을 자동적으로 생성하였다. 수집된 이미지 데이터를 바탕으로 다층퍼셉트론을 사용하여 분류 모델을 학습한다. 이를 활용하여 다중 클래스 분류를 통해 동영상 생성에 사용할 이미지의 분위기를 예측하며, 미리 분류된 음악을 매칭시켜 동영상을 생성한다. 10겹 교차 검증의 결과, 72.4%의 정확도를 얻을 수 있었고, 실제 영상에 대한 실험에서 64%의 오차 행렬 정확도를 얻을 수 있었다. 오답의 경우, 주변의 비슷한 분위기로 분류하여 동영상에서 나오는 음악과 크게 위화감이 없음을 확인하였다.

• Journal of Yeungnam Medical Science
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• 제39권1호
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• pp.46-52
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• 2022

Background: The coronavirus disease 2019 (COVID-19) outbreak in the Daegu-Gyeongbuk area in 2020 has caused difficulties in the daily life and hospital care of children with type 1 diabetes mellitus (T1DM). We detected an increase in blood sugar levels in these children and the number of patients hospitalized with more severe diabetic ketoacidosis (DKA) compared to those before COVID-19. Methods: This single-center study was conducted at Kyungpook National University Children's Hospital. The following patient groups were included; 45 returning patients diagnosed with T1DM and undergoing insulin treatment for more than 2 years and 20 patients newly diagnosed with T1DM before and after COVID-19 were selected by age matching. Returning patients before and after the outbreak were selected, and changes in hemoglobin A1c (HbA1c) levels were retrospectively reviewed. The HbA1c levels and severity of symptoms in newly diagnosed patients during hospitalization were examined. Results: HbA1c levels in returning patients with T1DM were significantly increased after COVID-19 (before, 7.70%±1.38% vs. after, 8.30%±2.05%; p=0.012). There were 10 and 10 newly diagnosed patients before and after COVID-19, respectively. The proportion of patients with drowsiness and dyspnea at the time of admission was higher after COVID-19 than before (before, 2 of 10 vs. after, 4 of 10). The HbA1c levels were higher in newly diagnosed patients hospitalized after COVID-19 than before (before, 11.15% vs. after, 13.60%; p=0.036). Conclusion: Due to COVID-19 in the Daegu-Gyeongbuk area, there was an increase in blood glucose levels in children with T1DM and in the incidence of severe DKA in newly diagnosed diabetes mellitus patients.

• Smart Structures and Systems
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• 제31권4호
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• pp.393-407
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• 2023

To assess structural condition in a non-destructive manner, computer vision-based structural health monitoring (SHM) has become a focus. Compared to traditional contact-type sensors, the advantages of computer vision-based measurement systems include lower installation costs and broader measurement areas. In this study, we propose a novel computer vision-based vibration measurement and coarse-to-fine damage assessment method for truss bridges. First, a deep learning model FairMOT is introduced to track the regions of interest (ROIs) that include joints to enhance the automation performance compared with traditional target tracking algorithms. To calculate the displacement of the tracked ROIs accurately, a normalized cross-correlation method is adopted to fine-tune the offset, while the Harris corner matching is utilized to correct the vibration displacement errors caused by the non-parallel between the truss plane and the image plane. Then, based on the advantages of the stochastic damage locating vector (SDLV) and Bayesian inference-based stochastic model updating (BI-SMU), they are combined to achieve the coarse-to-fine localization of the truss bridge's damaged elements. Finally, the severity quantification of the damaged components is performed by the BI-SMU. The experiment results show that the proposed method can accurately recognize the vibration displacement and evaluate the structural damage.

• Safety and Health at Work
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• 제15권2호
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• pp.151-157
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• 2024

Background: Replacement drivers represent a significant portion of platform labor in the Republic of Korea, often facing night shifts and the demands of emotional labor. Research on replacement drivers is limited due to their widespread nature. This study examined the levels of presenteeism and absenteeism among replacement drivers in comparison to those of paid male workers in the Republic of Korea. Methods: This study collected data for replacement drivers and used data from the 6th Korean Working Conditions Survey for paid male workers over the age of 20 years. Propensity score matching was performed to balance the differences between paid workers and replacement drivers. Multivariable logistic regression was used to estimate the adjusted odds ratio (OR) and 95% confidence intervals for presenteeism and absenteeism by replacement drivers. Stratified analysis was conducted for age groups, educational levels, income levels, and working hours. The analysis was adjusted for variables including age, education, income, working hours, working days per week, and working duration. Results: Among the 1,417 participants, the prevalence of presenteeism and absenteeism among replacement drivers was 53.6% (n = 210) and 51.3% (n = 201), respectively. The association of presenteeism and absenteeism (adjusted OR [95% CI] = 8.42 [6.36-11.16] and 20.80 [95% CI = 14.60-29.62], respectively) with replacement drivers being significant, with a prominent association among the young age group, high educational, and medium income levels. Conclusion: The results demonstrated that replacement drivers were more significantly associated with presenteeism and absenteeism than paid workers. Further studies are necessary to establish a strategy to decrease the risk factors among replacement drivers.

• Annals of Occupational and Environmental Medicine
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• 제34권
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• pp.1.1-1.13
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• 2022

Background: Recently, there has been a call to improve the holistic welfare of dependent contractors (DCs). Thus, our study examined the relationship between DCs and mental health symptoms and how this relationship was modified by age, sex, and income status of workers. Methods: A total of 27,980 workers from the Fifth Korean Working Conditions Survey are included in our study. The participants who reported having depression or anxiety over the last 12 months are defined those who had mental health symptoms. We performed exact matching for age group and sex, followed by conditional logistic regression with survey weights. Finally, stratified analyses by age, sex and income level were conducted. Results: DCs were found to be at increased risk of depression/anxiety compared to other workers. The odds ratio (OR) is 1.52 (95% confidence interval [CI]: 1.06-2.17). In the stratified analyses, vulnerable groups were middle-aged (OR [95% CI]: 1.68 [1.10-2.54]), female (OR [95% CI]: 1.85 [1.20-2.84]), and low-income (OR [95% CI]: 3.18 [1.77-5.73]) workers. Conclusions: Our study's results reinforce those of other studies that show that DCs are at greater risk of experiencing mental health issues than other workers and that and this risk is greater for middle-aged, female, and low-income workers. These results suggest that appropriate policy efforts should be made to improve the psychological well-being of DCs.

• 대한핵의학회지
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• 제32권5호
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• pp.414-424
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• 1998

목적: PET과 MR 영상을 체계적으로 합성i분석하여 각각의 영상기법이 갖는 단점을 보완하고 기능을 향상시킴으로써 보다 정확하고 유용한 임상정보를 얻을 수 있다. 두 영상을 공간적으로 합성하기 위해서 머리 표피 경계점들 간의 거리를 최소화하는 알고리즘을 이용할 경우 경계점 추출의 정확성 및 견실성과 거리 계산 속도가 합성 알고리즘의 성능을 결정하는 중요한 요소가 된다. 본 연구에서는 PET 영상의 경계 추출과 거리 계산 방법을 개선하고 이를 이용하여 PET과 MR 영상을 3차원적으로 합성하였다. 대상 및 방법: 공간적인 합성을 위한 영상처리기법의 핵심인 경계점 추출을 위해 PET영상에서는 방출스캔 sinogram의 경계를 강조한 후 재구성한 횡단면으로부터 2 mm 간격으로 머리 표피 경계점들을 추출하였으며 MR 영상에서는 각 횡단면마다 약 2도 간격으로 경계점들을 추출하였다. 두 영상의 모든 경계점들 간의 평균 유클리디안 거리를 최소화하는 3차원 가상공간 상에서의 위치 이동과 회전 각도를 최소자승법을 이용하여 구한 후 PET영상을 역 전환하여 위치 정합을 하였다. 평균 거리의 계산 속도를 향상시키기 위하여 고정된 대상의 각 경계점을 중심으로 하여 주변 공간 정들에서의 거리를 순차적으로 계산하고 이들의 최소값을 취하는 방법으로 거리지도를 구성하였으며 최소자승법에서 경계점들 간의 위치가 변할 때마다 매번 평균거리를 다시 계산하지 않고 거리지도를 참조하여 평균 거리를 산출하는 방법을 사용하였다. 위치 정합된 두 영상의 동시 표현을 위하여 PET 영상의 화소값에 $0.4{\sim}0.7$부터 1사이의 범위로 정규화된 MR 영상의 화소 값으로 가중치를 주는 가중정규화 방법을 사용하였다. 결과: 방출스캔의 sinogram을 이용함으로써 PET영상의 경계를 견실하게 추출할 수 있었으며, 거리지도를 이용하여 거리 계산을 한 결과 계산 속도를 향상시킬 수 있었다. 정상인의 뇌영상에 대해 위치 정합을 실시한 결과 평균 거리 오차는 2mm 이하였다. 가중정규화 방법을 사용하였을 때 합성된 영상의 정성적인 식별 명확도가 향상하였다. 결론: 견실한 PET 영상 경계점 추출과 거리지도를 이용한 계산 속도의 향상을 통해 뇌 PET과 MR 영상 합성기법의 성능을 개선할 수 있었으며 이를 이용하며 개발한 영상정합 프로그램은 임상 환경에서 유용하게 사용될 수 있을 것이다.

• 한국산업보건학회지
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• 제24권4호
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• pp.536-546
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• 2014

Objectives: The major objective of this paper is compare the exposure work hours and experieence of ill health symptoms among under and over employment and matched group. Workers with over employment have more exposed to hazards than that with under employment because that workers with over employment work more than those with ender employment. Methods: This study as heuristics one used the third Korean Working Conditions Survey done by Occupational Safety and Health Research Institute in 2011. The sample size is 50,023 economic active persons. Over and under employment were measured by matching method of preferred and actual work hours. The exposed work hours to hazards were measured according to 13 hazardous factors and the experience of ill health symptoms were scaled by the number of experienced 14 ill health symptoms. To compare the exposure and the symptoms experience were compared by mean difference test with F test. Results: The proportion of over employment in male employees is 32.1% and that in female employees is 29.3% and under employment rate is 11.2% in mae and 13.9% in female employees. There is significant difference of the rate of over and under emplyment among age groups, industrial sectors, occupational groups and the state of employment. The difference of the exposed work hours to hazards among under, over and matched group were statistically significant in all hazards by gender. The exposed work hours to hazards in over employment were more than those in under employment. The number of experienced symptoms in over employment is statistically significantly more than that in under employment. Conclusions: Workers with over employment may be vulnerable group in the criteria of hazard exposure and health status. The results have some implications and limitations because that this study is heuristic one. The mismatch of preferred and actual working hours may be unfavorable work condition that has impact on safety and health of workers. The impact mechanism may be investigated as future study, Because that this study used cross sectional survey data, some causal relationships cannot be evaluated.