• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.47-48
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• 2007

A CMP Process has many factors that affect result of a polished wafer. Dominant factors are velocity, pressure and temperature in process. A pad profile is also considered as affecting factor of CMP. Accoding to variation of a pad profile, the each pan of a wafer is differently pressured. It appears to affect the uniformity of a wafer. A pad profile varies as a swing arm conditioner which have been ordinarily used in industry. A swing arm conditioner has several sectors in its swing path. This study aims that a wafer get a good uniformity as swing arm conditioner's path on pad is analyzed and simulated. Through the simulation, tendency of pad profile after conditioning will be predicted and the result of simulation compared with the result of experiment. The optimized pad profile would be made by to vary swing arm's velocity on each sector. In order to maintain the optimized profile, conditioner design or swing arm's velocity should be changed and designed.

• 아태비즈니스연구
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• 제11권3호
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• pp.199-215
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• 2020

Purpose - This article tries to test if the conditional consumption capital asset pricing model (CCAPM) with bank credit for household as a conditional variable can explain the cross-sectional variation of stock returns in Korea. The performance of conditional CCAPM is compared to that of multifactor asset pricing models based on Arbitrage Pricing Theory. Design/methodology/approach - This paper extends the simple CCAPM to the conditional version of CCAPM by using bank credit for household as conditioning information. By employing KOSPI and KOSDAQ stocks as test assets from the second quarter of 2003 to the first quarter of 2018, this paper estimates risk premiums of conditional CCAPM and a variety of multifactor linear models such as Fama-French three and five-factor models. The significance of risk factors and the adjusted coefficient of determination are the basis for the comparison in models' performances. Findings - First, the paper finds that conditional CCAPM with bank credit performs as well as the multifactor linear models from Arbitrage Pricing theory on 25 test assets sorted by size and book-to-market. When using long-term consumption growth, the conditional CCAPM explains the cross-sectional variation of stock returns far better than multifactor models. Not only that, although the performances of multifactor models decrease on 75 test assets, conditional CCAPM's performance is well maintained. Research implications or Originality - This paper proposes bank credit for household as a conditional variable for CCAPM. This enables CCAPM, one of the most famous economic asset pricing models, to conform with the empirical data. In light of this, we can now explain the cross-sectional variation of stock returns from an economic perspective: Asset's riskiness is determined by its correlation with consumption growth conditional on bank credit for household.

• 한국항행학회논문지
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• 제26권1호
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• pp.35-45
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• 2022

본 논문에서는 PV 시스템에서 태양광 발전 시스템의 완전한 동작을 위해 DC-DC 벅-부스트 컨버터와 MPPT (Maximum Power Point Tracking)제어 시스템에 대한 완전한 동작 시스템에 대해 모델링하고 시뮬레이션을 수행하여 양호한 동작을 확인하고자 한다. 이를 위해 이중층 커패시터(EDLC:Electric double-layer capacitors )를 사용한 순간전압강하 보상장치가 개발되어 적용되고 있다. 따라서 태양광 발전의 ESS(Energy Storage System)를 고려한 PCS(Power Conditioning System)를 제안하여 부하평준화를 통한 전력의 안정적인 공급을 확인한다. 본 논문에서는 순간전압강하 보상장치(DVR :Dynamic Voltage Restorer)에 사용되는 전기 이중층 커패시터에 비해 동일 사이즈 대비 에너지 밀도가 높은 하이브리드 커패시터(hybrid capacitor)를 적용하는 연구를 하였고, 단상 3[kW] 계통 연계형 태양광 전력변환기를 제안하였다.

• Current Research on Agriculture and Life Sciences
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• 제33권1호
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• pp.25-31
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• 2015

본 연구는 시설원예 작물 재배 농가들을 대상으로 응답자들의 항목별 선호도를 분석하고, 농업현장에서 농민들이 체감하는 원예단지에 대한 만족도와 문제점을 파악하고 평가하고자 하였다. 분석 대상은 크게 생산관련 소모품 공동구입, 온실시설 기자재 공동구입, 공동 육묘 생산, 공동 냉난방시설 사용, 공동출하, 토양 검사 및 인증제도를 포함하는 공동 활동부분과 생산기술정보, 온실시설관리정보, 유통관련정보, 생산기술교육, 온실시설관리교육, 유통관련교육을 포함하는 정보교류 및 교육부분으로 나누었다. 공동활동 부분의 IPA분석결과 소모품 공동구입, 기자재 공동구입, 공동출하 항목이 중요도와 만족도가 모두 높아 지속적인 유지가 필요하며, 공동육묘 생산, 공동냉난방 시설 등 2개 항목은 중요도와 만족도가 모두 낮아 우선순위를 낮추어도 될 것으로 판단된다. 소모품 및 기자재 공동구입에 대한 단지별 생산자 니즈를 파악하고, 원예전문생산단지가 수출집중형인 경우에는 공동출하 체계를 적극 활용해 수출대상국별 경쟁력 있는 교섭권을 더욱 강화해 나가야 할 것이다. 한편, 육묘장과 냉난방시설의 경우, 정부지원을 받아 시설을 소유하고 있는 비율이 높기 때문에 중요도-만족도가 낮은 것으로 판단된다. 그러나 $CO_2$ 저감을 위한 환경친화적 신재생 에너지의 활용 및 지속가능한 농업의 관점에서 고찰해보면, 에너지 이용 효율성 제고 및 환경 친화적 원예단지 조성이 중요한 부분이라는 것을 인지해야 할 것이다. 또한, 토양 검증 및 인증 항목은 중요도에 비해 만족도가 높아 과잉관리가 개선될 필요성이 있는 것으로 나타났다. 이러한 결과는 원예전문생산단지 평가 지표에서 가점을 주는 평가항목들이기 때문에 이미 잘 관리가 되고 있는 것으로 설명할 수 있다. 정보교류 및 교육부문의 IPA분석결과 가장 집중적으로 관리되어야 할 요인으로 생산기술 교육이었으며, 원예전문단지 교육을 실시하기 위해서는 생산기술 교육을 타 교육(온실관리 및 유통관련 교육) 보다 집중적으로 실시해야할 부분으로 평가할 수 있다. 생산기술 정보, 온실시설 관리정보, 유통관련 정보는 중요도와 만족도가 모두 높아 지속적으로 잘 유지해야 할 필요가 있는 요인들이다. 다양한 정보에 대한 응답자들의 중요도와 만족도가 높기 때문에, 농가들의 적극적인 정보 교류를 활성화 시키는 방안을 제시할 수 있을 것이다. 예를 들면, 구성원들의 정보교류 어플리케이션, SNS 활동 혹은 홈페이지 활용, 공식적인 정기모임 및 정보교류 회의를 위한 협의체를 구성 등을 들 수 있겠다. 온실관리 교육, 유통관련 교육의 2개 요인에 대해서는 우선순위를 낮추어도 좋은 것으로 판단된다. 마지막으로 생산성 향상 및 시설원예의 경쟁력 강화를 위해 정부 주도의 시설원예단지 규모는 더욱 확대될 것이므로, 본 연구의 결과가 원예전문생산단지의 운영에 효율적으로 적용되기를 기대한다.

• Progress in Superconductivity
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• 제8권1호
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• pp.33-39
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• 2006

We have developed a second-order double relaxation oscillation SQUID(DROS) gradiometer with a baseline of 35 mm, and constructed a poorly magnetically-shielded room(MSR) with an aluminum layer and permalloy layers for magnetocardiography(MCG). The 2nd-order DROS gradiometer has a noise level of 20 $fT/{\surd}Hz$ at 1 Hz and 8 $fT/{\surd}Hz$ at 200 Hz inside the heavily-shielded MSR with a shielding factor of $10^3$ at 1 Hz and $10^4-10^5$ at 100 Hz. The poorly-shielded MSR, built of a 12-mm-thick aluminum layer and 4-6 permalloy layers of 0.35 mm thickness, is 2.4mx2.4mx2.4m in size, and has a shielding factor of 40 at 1 Hz, $10^4$ at 100 Hz. Our 64-channel second-order gradiometer MCG system consists of 64 2nd-order DROS gradiometers, flux-locked loop electronics, and analog signal processors. With the 2nd-order DROS gradiometers and flux-locked loop electronics installed inside the poorly-shielded MSR, and with the analog signal processor installed outside it, the noise level was measured to be 20 $fT/{\surd}Hz$ at 1 Hz and 8 $fT/{\surd}Hz$ at 200 Hz on the average even though the MSR door is open. This result leads to a low noise level, low enough to obtain a human MCG at the same level as that measured in the heavily-shielded MSR. However, filters or active shielding is needed fur clear MCG when there is large low-frequency noise from heavy air conditioning or large ac power consumption near the poorly-shielded MSR.

• 대한예방한의학회지
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• 제10권1호
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• pp.109-121
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• 2006

The purpose of this study was to determine factors influencing patient satisfaction with medical services in hospital, which is classified into environmental aspect, human services and procedural services. Based on the results of literature review, the study focused on effects of social-demographical factors on patient satisfaction. The environmental aspect of medical care services included medical equipment and facilities, hygiene, ventilation, heating and air-conditioning, waiting and resting space, ward space and parking facilities. Procedural service included registration process, bill payment, waiting time after registration, examination and prescription as well as appointment process. Human services consisted of physicians listening to stories of patients, examination duration, physicians' explanation and physicians' service. As for nurses, explanation about disease, examination procedure and results, kindness and nursing care were evaluated. Services provided by other staff members were also evaluated. Patient satisfaction, defined as individual attitude toward medical service as a whole, was measured using a questionnaire. A total of 700 in-or out-patients were surveyed in 6 hospitals with more than 300 beds in North Gyeongbuk Province. 1. The level of patient satisfaction varied with characteristics of patients. Male patients and those in their 30s had a low level of satisfaction. Dissatisfaction level was positively related to education level but negatively related to economic condition. 2. As for patient satisfaction with medical service providers and other employees in hospital, satisfaction level with physician's explanation about treatment was higher. But dissatisfaction levels with treatment duration and the lack of explanation about examination procedures were high, calling for improvement. Dissatisfaction level with nursing care was high, calling for training of nurses for better service. Given the low level of satisfaction with human services, hospital employees need to be trained to improve their service. 3. It Was found that administrative service was also a significant factor influencing patient satisfaction in addition to medical service. It is therefore important for hospitals to provide patients with prompt and convenient procedural service. 4. Environmental factors such as medical equipment and amenity facilities also affected patient satisfaction. Thus environmental condition, procedural service and human service are all important to improve medical service in hospital. In summary, procedural service was the most significant factor for patient satisfaction. The level of satisfaction in patients was also affected by human service and environmental condition. It is therefore necessary to take patient-oriented approach in providing medical service in an effort to improve patient satisfaction. The finding of a lower level of satisfaction with human service signifies the need for training of healthcare providers and other hospital employees for better services. The introduction of advanced management programs is also needed to improve procedures that patients go through in hospitals.

• IMMUNE NETWORK
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• 제15권2호
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• pp.66-72
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• 2015

Currently, detecting biochemical differences before and after allogeneic stem cell transplantation (SCT) for improved prediction of acute graft-versus-host disease (aGVHD) is a major clinical challenge. In this pilot study, we analyzed the kinetics of circulating adipokine levels in patients with or without aGVHD before and after allogeneic SCT. Serum samples were obtained and stored at $-80^{\circ}C$ within 3 hours after collection, prior to conditioning and at engraftment after transplantation. A protein array system was used to measure the levels of 7 adipokines of patients with aGVHD (n=20) and without aGVHD (n=20). The resistin level at engraftment was significantly increased (p<0.001) after transplantation, regardless of aGVHD occurrence. In the non-aGVHD group, the concentrations of the hepatocyte growth factor (HGF) (mean values${\pm}$SD; $206.6{\pm}34.3$ vs. $432.3{\pm}108.9pg/ml$, p=0.040) and angiopoietin-2 (ANG-2) (mean values${\pm}$SD; $3,197.2{\pm}328.3$ vs. $4,471.8{\pm}568.4pg/ml$, p=0.037) at engraftment were significantly higher than those of the pre-transplant period, whereas in the aGVHD group, the levels of adipokines did not change after transplantation. Our study suggests that changes in serum HGF and ANG-2 levels could be considered helpful markers for the subsequent occurrence of aGVHD.

• 대한기계학회논문집B
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• 제39권9호
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• pp.761-772
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• 2015

가정용 에어컨이나 히트 펌프에 외경 7.0 mm 마이크로핀 튜브가 널리 사용되고 있다. 한편 에어컨이나 히트펌프의 부분 부하 운전시 질량유속은 수십 $kg/m^2s$에 불과하다. 하지만 7.0 mm 튜브에 대한 기존 연구들은 질량유속 $100kg/m^2s$ 이상에서 수행되었다. 본 연구에서는 낮은 질량유속 ($50kg/m^2s$에서 $250kg/m^2s$)에서 외경 7.0 mm 마이크로핀 튜브 내 R-410A 증발 열전달 실험을 수행하였다. 실험 중 포화온도는 $8^{\circ}C$, 열유속 $4.0kW/m^2$으로 유지하였다. 비교를 위해 외경 7.0mm 평활관에 대한 실험도 수행하였다. 실험결과 마이크로핀 튜브의 전열촉진비는 질량유속이 감소할수록 증가하다 $150kg/m^2s$를 기점으로 감소함을 보였다. 이는 마이크로 핀튜브 내 유동이 환상류에서 성층류로 변화하기 때문이다. 실험 범위에서 마이크로핀 튜브의 마찰손실과 평활관의 마찰손실은 거의 같게 나타났다. 실험데이터를 기존 상관식의 예측치와 비교하였다.

• 한국가금학회지
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• 제33권3호
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• pp.239-248
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• 2006

발효가 가능한 탄수화물을 이용하거나 효소 이용 및 사료가공 등에 관한 이해를 증진시키는 길은 닭의 분중 휘발성 유가물질의 감소를 가져올 수 있다. 전분질의 소화는 가루사료를 (밀과 보리) 알곡으로 대치하게 하였다. 그러나 근위의 pH로 볼 때 사료의 종류나 형태는 연속성이 떨어진다. 펠렛으로 만든 사료는 사료 요구율이 $0\siml2%$ 증진된다. 전분질의 소화는 xylase를 첨가하였을 때 대사 에너지(ME) 가는 35% 증진 효과가 잇는 것으로 보고되었다. 전분질의 이용과 전분질이 아닌 다당류(NSP)의 이용은 전분질을 포함한 알갱이 사료의 존재 즉 비 영양소 물질(ANF)의 포함 여부에 달려 있다. 사료 생산 기술의 증가는 $33^{\circ}C$에서 만들어지는 펠렛 사료에 이용될 수 있는 건조된 상태의 효소나 액체상태의 효소 생산 기법에 달려 있다. 수용성 NSP나 arabinoxylans 또는 beta-glucan 등은 부분적으로 효소 가격이 크기로 나누어지는 정도에 따라 달라진다. 적은 크기는 수분 흡수력이 감소되어야 하는데 만약 수분 흡수력이 지나치면 소화물에 수분이 너무 많아지게 되어 분에 수분 함량이 많아지며 사료 곡물 중에 비스코시티 현상이 생겨서 계란 껍질이 지저분해진다.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.422-428
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• 2003

Umbilical cord blood (UCB), a rich source of hematopoietic stem/progenitor cells, has been proposed as an alternative to bone marrow and peripheral blood for transplantation treatment. Ex vivo expansion of cord blood stem cells could make the use of cord blood transplant feasible even for adult patients. However, the optimal cytokine cocktail for expansion of stem cells is yet to be established. This study compares proliferation, apoptosis, and telomerase activities in human cord blood stem cells cultured ex vivo with FLT3 ligand (FL)/thrombopoietin (TPO) or FL/TPO/stem cell factor (SCF), with a view to determine optimal combination of cytokines. CD34+ cells were cultured in DMEM containing either FL (50 ng/ml) and TPO (10 ng/ml) (FT group) or FL (50 ng/ml), TPO (10 ng/ml) and SCF (50 ng/ml) (FTS group). The cell proliferation rate was ten times higher in the FTS group. Although cells cultured with the two different combinations of cytokines were maintained for a long term (up to 8 weeks), a large number of cells underwent differentiation during this period. Cells cultured in FTS displayed lower levels of apoptosis compared to those of the FT group during the Initial 7 days of culture. The CD34+ fraction in both groups was markedly decreased to $21-30\%$ , and only $5-6\%$ was detected at 14 days of culture. Telomerase activity detected in human CD34+ cord blood at low levels was upregulated during the early phase of culture and decreased to baseline levels in the later phase. The telomerase activity of cord blood cultured in FT was lower than that of the FTS group. Our results suggest that, on adding stem cell factors to the FT cytokines, cultured CD34+ cord blood cells display a greater degree of cell proliferation and decreased apoptosis. However, during CD34+ cord blood cell culture, a Barge number of cells undergo differentiation, indicating that more potent novel cytokines or new culture conditioning methods should be developed to maintain their ability to engraft and sustain long-term hematopoiesis.