• 한국ITS학회 논문지
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• 제17권3호
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• pp.46-58
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• 2018

농어촌지역에서 수요응답형교통(demand response transport, DRT)이 정착하기 위해서는 수요부족의 문제가 있는 농어촌버스보다 긍정적 측면이 많아야 된다. 연구는 기존 농어촌버스와 DRT가 혼용 운행되고 있는 지역에서 DRT의 중요도와 실행도(importance- performance analysis, IPA)를 분석하고, 농어촌버스 만족도와의 관계성 분석하기 위해 IPA의 불일치 이론을 적용한다. IPA 결과로 가장 시급한 개선항목은 DRT 운행범위이며 환승위치, 환승시간, 환승거리, 정시도착, 안전운전, 운행시간, 차량수가 개선항목이다. 불일치이론 결과 농어촌버스와 비교하여 DRT 활성화를 위해서는 실행도보다 중요도가 큰 경우, 환승 편리성, 운행 시간 및 범위, 운행차량에 대해 실행도를 높인다. 실행도보다 중요도가 작은 경우 차량청결도, 안전운전, 운영자 친절, 환승요소, 운행요소, 요금은 지속적인 실행도가 유지되도록 한다.

• Clinical and Experimental Reproductive Medicine
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• 제30권1호
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• pp.57-64
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• 2003

Objective : We investigate the effects of multiple attempts of embryo transfer because of retained embryos in the catheter and of contaminated mucus on the transferred catheter. Materials and Methods: We respectively analysed data between November 1998 and August 2002 from 305 patients of 369 cycles who underwent IVF-ET. Of these patients, 47 patients of 50 cycles (Group 2) were required multiple trial of embryo transfer. They were compared with an age-matched control groups (Group 1) with female factor infertility. Pearson's $?^2$ and Fisher's tests were used to compare proportions between discrete variables. Noncategorical data were compared using t-test. Statistical significance was set at p<0.05. Results: Embryos were significantly more likely to be retained when catheter was contaminated with mucus (Group 1: 22.4%; Group 2: 44.0%). The clinical pregnancy rates, however, for the contaminated mucus or not, were 46.8%, 43.5% respectively. There was no significant difference clinical pregnancy rate between those who had all their embryos transferred at the first attempt (45.4%) and those who required more than one attempt (48.0%). Conclusions: Contaminated mucus in the catheter is associated with failed embryo transferred at the first attempt. Embryo transfers, however, that are repeated attempts do not adversely affect pregnancy rates following IVF-ET.

• Journal of Welding and Joining
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• 제16권4호
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• pp.39-46
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• 1998

$CO_2$ gas shielded arc welding has been characterized with its harsh arc compared to Ar-based shielding gases and with its high level of spattere specially in welding current range of 250~300 amperes. In this range of welding current, the metal transfer mode showed to be changed from short circuit to globular with the increase of welding voltage resulting in so-called the transitional mode in which both modes of transfer appeared together. To characterize the transitional mode, the short circuit events were divided into two groups, i.e. normal short circuit (N.S.C) which has short circuit time $(t_s)$ over 2msec and instantaneous short circuit (I.S.C) of $t_s$$\leq$2msec. The experimental results showed that the number of N.S.C decreased almost linearly with the increase of welding voltage and appeared to be not related with spatter generation rate. However I.S.C became to be pronounced in the transitional condition and its number reached the maximum value at around 29.0 volts. Considering the relation with the spatter generation rate, it was found that the number of I.S.C had a very strong correlation with the spatter generation rate of the transitional condition. It was further demonstrated that spatter generation rate decreased quite linearly with the decrease of I.S.C frequency. It implies that I.S.C is the most important waveform factor controlling the spatter generation of the transitional mode, i.e. in the middle range of welding current. Based on these results, It was discussed that in the transitional mode the basic concept of waveform control for suppressing spatter generation would be different from the one applied for typical short circuit transfer mode of low welding current.

• 설비공학논문집
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• 제16권12호
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• pp.1234-1268
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• 2004

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2002 and 2003 has been carried out. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment/design. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation in diverse facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat transfer, humidity was also interesting to promote comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing research topics. Well developed CFD technologies were widely applied for analysis and design of various facilities and their systems. (2) Heat transfer characteristics of enhanced finned tube heat exchangers and heat sinks were extensively investigated. Experimental studies on the boiling heat transfer, vortex generators, fluidized bed heat exchangers, and frosting and defrosting characteristics were also conducted. In addition, the numerical simulations on various heat exchangers were performed and reported to show heat transfer characteristics and performance of the heat exchanger. (3) A review of the recent studies shows that the performance analysis of heat pump have been made by various simulations and experiments. Progresses have been made specifically on the multi-type heat pump systems and other heat pump systems in which exhaust energy is utilized. The performance characteristics of heat pipe have been studied numerically and experimentally, which proves the validity of the developed simulation programs. The effect of various factors on the heat pipe performance has also been examined. Studies of the ice storage system have been focused on the operational characteristics of the system and on the basics of thermal storage materials. Researches into the phase change have been carried out steadily. Several papers deal with the cycle analysis of a few thermodynamic systems which are very useful in the field of air-conditioning and refrigeration. (4) Recent studies on refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement when new alternative refrigerants are applied. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and new alternative refrigerants including natural refrigerants. Efficiency of various compressors and performance of new expansion devices are also dealt with for better design of refrigeration/air conditioning system. In addition to the studies related with thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out. It should be noted that the researches on two-phase flow are constantly carried out. (5) A review of the recent studies on absorption refrigeration system indicates that heat and mass transfer enhancement is the key factor in improving the system performance. Various experiments have been carried out and diverse simulation models have been presented. Study on the small scale absorption refrigeration system draws a new attention. Cooling tower was also the research object in the respect of enhancement its efficiency, and performance analysis and optimization was carried out. (6) Based on a review of recent studies on indoor thermal environment and building service systems, it is noticed that research issues have mainly focused on several innovative systems such as personal environmental modules, air-barrier type perimeterless system with UFAC, radiant floor cooling system, etc. New approaches are highlighted for improving indoor environmental conditions and minimizing energy consumption, various activities of building energy management and cost-benefit analysis for economic evaluation.

• 한국수정란이식학회지
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• 제31권4호
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• pp.335-347
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• 2016

Multiple interferon tau (IFNT) genes exist in bovine. An antiluteolytic substance secreted by the bovine conceptus and primarily responsible for maternal recognition of pregnancy is bovine trophoblast protein 1 (bIFNT1), a new type I interferon tau (IFNT) genes. The objectives of this research were to investigate whether multiple, distinct gene encode bIFNT1 and other type I bIFNT gene in the bovine genome and to examine expression of bIFNT1 and other bIFNTc1 mRNAs during conceptus development. These transcrips could be regulated through caudal-related homeobox-2 (CDX2) and ETS2 and/or AP1 (JUN) expression, a transcription factor implicated in the control of cell differentiation in the trophectoderm. The presence of mRNAs encoded by bIFNT1 and type I bIFNTc1 genes were examined quantitatively via reverse transcription-polymerase chain reaction (RT-PCR) analysis of total cellular RNA (tcRNA) extracted from on day 17, 20 and 22 bovine conceptuses. The expression level of bIFNT1 was higher on day 17 transcripts were gradually weakly detectable on day 20 and 22. However, the other bIFNTc1 gene examined transcripts was highly expressed on day 20 and transcripts were weakly detectable on day 17 and 22 bovine conceptuses. Furthermore, human choriocarcinoma JEG3 was co-transfected with an -1kb-bIFNT1/c1-Luc constructs and several transcription factor expression plasmids. Compared to each -1kb-bIFNT1/c1-Luc increased when this constructs were co-transfected with, ETS2, AP1(JUN), CREBBP and/or CDX2. Also, bIFNTc1 gene was had very effect on activity by alone ETS2, and AP1 (JUN) expression factors in choriocarcinoma JEG3 cell. However, bIFNT1 gene expression of the upstream region was not identified. We demonstrated that the activities of bIFN genes are regulated by differential, tissue-specific and developmental competence during pregnancy.

• Journal of Preventive Medicine and Public Health
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• 제31권2호
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• pp.293-309
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• 1998

The purpose of this study is to compare the level of health-related quality of life and relating factor between institutional elderly and community living elderly. The subjects were 390 from Sanatorium or Nursing home and 467 from the community in Kwangju. The results are followed : 1) A comparison of ADL between two groups, institutional elderly and community living elderly, resulted in that community elderly were more significantly independent in the areas of bathing and transfer than institutional elderly. 2) A comparison of IADL between two groups resulted in that : Community elderly were more independent in the areas of using telephone and transportation, food preparation, house keeping, and doing laundry. Institutional elderly were more independent in the area of handling finances. 3) In the case of poor health-related quality of life, institutional elderly showed 2.4 times in the dimension of physical fitness, 1.8 times in daily activity, 2 times in social activity, 2 times in pain, 26.7 times in social support, and 0.4 times in subjective quality of life higher than community elderly There was no significant differences in the rest of dimensions. 4) In institutional elderly, the analysis of variables related to the health-related quality of life resulted in that; The relating factors were sex, education, and chronic illness in the dimension of physical function. Direct contact with family or significant others in the dimension of social activity. Chronic illness in the dimension of pain and perceived health status. Direct or indirect contact with family or significant others over the phone or through letters in the dimension of social support. 5) The analysis of variables related to the health-related quality of life showed that community elderly has more relating variables in each area than institutional elderly. The relating factors were age, sex, and chronic illness in the dimension of physical function. Education and chronic illness in the dimension of emotional status. Age and chronic illness in the dimension of daily activity and social activity Education and chronic illness in the dimension of pain and perceived health status. Sex, education, family size in the dimension of social support. Education and chronic illness in the dimension of subjective quality-of-life. Throughout general daily activity, community elderly showed more satisfactory results than institutional elderly, but in the subjective area of health-related quality of life, such as subjective quality of life, institutional elderly group showed more positive results. And community elderly had more relating factors than institutional elderly. For the health care of the elderly that focused on quality of life, new approaches considering the characteristics of both group, institutional and community living elderly, are needed.

• Communications for Statistical Applications and Methods
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• 제17권5호
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• pp.697-712
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• 2010

이 연구의 목적은 우리나라 생명보험사들의 보험계약대출(약관대출) 수요에 대한 통계적 분석과 그 예측을 위한 확률모형을 개발하는 데 있다. 이를 위해, 먼저 대출 금리가 정책적 변화를 거친 1999~2008 기간 동안 우리나라 보험계약대출의 수요계열에 대한 추세, 주기성, 종속성 등 확률 및 통계적 특성을 파악하였다. 다음에, 교차상관분석을 통해 대출수요와 인과관계를 가질 수 있는 경제변수들과의 상호관련성을 밝히고, 특히 소비자 물가지수가 보험계약대출 수요를 선도하고 있음을 밝혔다. 마지막으로, 이러한 결과를 기초로 보험계약대출 수요의 예측을 위한 단변수모형 그리고 선도변수계열을 이용한 전이함수모형을 각각 완성하고 그 효과를 비교 평가하였다. 마지막으로 유도된 확률모형을 이용하여 보험계약대출 수요예측의 통계적 절차를 제안하였다.

• 대한기계학회논문집B
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• 제34권7호
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• pp.703-714
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• 2010

본 연구에서는 크리깅 기법을 이용하여 엇갈린 핀휜이 부착된 회전하는 내부냉각유로의 형상 최적화를 수행하였다. 냉각유로 형상의 여러 매개변수 중 핀의 지름과 높이의 비, 핀의 지름과 핀과 핀 사이의 거리의 비를 최적설계를 위한 설계변수로 선택하였다. 열전달 관련 목적함수와 마찰손실 관련 목적함수를 가중계수를 이용하여 선형적으로 결합한 목적함수를 정의하였다. 크리깅 모델을 구축하기 위해 라틴하이퍼큐브 샘플링기법에 의해 생성된 20개 실험점에서 목적함수가 SST난류모델을 사용한 삼차원 레이놀즈평균 나비어-스톡스(RANS) 유동해석법에 의해 계산되었다. 크리깅 기법을 통하여 예측된 목적함수값은 RANS해석을 이용해 계산된 값과 매우 작은 오차 범위 내에서 일치하였으며, 최적설계를 통해 목적함수가 11% 감소하는 결과를 얻었다.

• 한국진공학회지
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• 제17권4호
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• pp.346-352
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• 2008

Eu을 이온주입한 GaN 시료에 대하여 Eu의 site들에 대한 연구와 Mg을 같이 도핑하였을 때의 효과를 분석하였다. 빨간색 광원으로 주목받는 620nm 근처의 Eu의 $^5D_0\;{\rightarrow}\;^7F_2$ 전이에 대하여 photoluminescence (PL) 와 PL 여기 분광법을 이용하여 GaN 내에서 Eu 이온이 자리하는 이미 알려진 2 개의 site 이외에도 2 종류의 site들이 있음을 확인하였다. 이들 중 한 site는 Mg의 codoping에 의하여 PL 크기가 약 1.6배 증가하였다. 이는 GaN의 밴드갭보다 작은 trap에 의해 에너지를 전달받는 Er이나 Nd보다 Mg의 도핑에 의한 효과가 매우 작은 것이다. GaN:Eu에서는 Mg과 관련된 trap을 통하지 않고 GaN에서 직접 Eu으로 에너지를 전달하기 때문으로 생각된다.

• 대한의용생체공학회:의공학회지
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• 제40권1호
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• pp.1-6
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• 2019

Human mesenchymal stem cells (hMSC) are multipotent stromal cells that have great potential to differentiate into a variety of cell types such as osteocytes, chondrocytes, and myocytes. Although there have been many studies on their clinical availability, little is known about how intracellular signals can be modulated by topographic features of the extracellular matrix (ECM). In this study, we investigated whether and how microwavy-patterned extracellular matrix (ECM) could affect the signaling activity of focal adhesion kinase (FAK), a key cellular adhesion protein. The fluorescence resonance energy transfer (FRET)-based FAK biosensor-transfected cells are incubated on microwavy-patterned surfaces and then platelet derived growth factor (PDGF) are treated to trigger FAK signals, followed by monitoring through live-cell FRET imaging in real time. As a result, we report that PDGF-induced FAK was highly activated in cells cultured on microwavy-patterned surface with L or M type, while inhibited by H type-patterned surface. In further studies, PDGF-induced FAK signals are regulated by functional support of actin filaments, microtubules, myosin-related proteins, suggesting that PDGF-induced FAK signals in hMSC upon microwavy surfaces are dependent on cytoskeleton (CSK)-actomyosin networks. Thus, our findings not only provide new insight on molecular mechanisms on how FAK signals can be regulated by distinct topographical cues of the ECM, but also may offer advantages in potential applications for regenerative medicine and tissue engineering.