• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.860-862
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• 1999

we have grown vertically aligned carbon nanotubes on a large area of Co-Ni codeposited Si substrates by thermal chemical vapor deposition using $C_{2}H_{2}$ gas. The carbon nanotubes grown by the thermal chemical vapor deposition are multi-wall structure, and the wall solace of nanotubes is covered with defective carbons or carbonaceous particles. The carbon nanotubes range from 50 to 120nm in diameter and about $130{\mu}m$ in length at $950^{\circ}C$. The turn-on voltage was about $0.8V/{\mu}m$ with a current density of $0.1{\mu}A/cm^2$ and emission current reveals the Fowler-Nordheim mode.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.496-496
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• 2012

Sputtering은 박막의 품질(부착력, 밀도, 균일도등)이 우수하고 대면적 증착이 용이하여 반도체, 디스플레이, MEMS기술등과 같은 첨단산업에서 널리 이용되고 있는 증착방법이다. 일반적인 평판형 스퍼터건은 전계와 자계가 직교하는 Target의 일부영역에서만 스퍼터링 현상이 발생하게 되어 증착물질의 사용효율이 20~30% 정도로 좋지 못하고 스퍼터링 되지않는 부분에서는 재증착 현상에 의한 파티클 발생을 유발하여 Substrate에 손상을 입혀 박막의 질을 떨어뜨리게 된다. 본 연구에서는 이러한 문제점들의 물리적 현상의 진단 및 최적화를 위해 Particle-In-Cell (PIC)시뮬레이션을 이용하여 그 특성들을 알아보았다. 인가전압, 압력, 증착물질과 기판사이의 거리를 변화시켜 자기장이 포함된 Paschen curve를 그렸다. 전기장만이 포함된 시스템에서의 Paschen curve는 이미 공식으로 알려져 있으며 마그네트론 스퍼터링의 시스템에서 Paschen curve와 비교하여 보다 낮은 압력에서 플라즈마가 형성할 수 있는 것을 확인하였다. 또한 Target에 충돌하는 아르곤이온의 양, 에너지 분포, 각도의 분포 등을 관찰하였는데, 대부분의 아르곤이온은 압력이 증가할수록 에너지가 큰 경향성을 가지며 입사각도는 Target에 보다 수직으로 충돌하는 경향을 볼 수 있었다. 증착물질과 기판사이의 거리의 변화에 대해서는 이온 특성의 변화는 없었다.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.141-144
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• 2019

Oil-water separators are commonly used in the oily wastewater treatment for the reuse of water resources. Recently, various approaches have been conducted to design and manipulate the oil-water separator installed with highly functionalized membranes. Membrane technologies should encompass the selectivity, durability, economics and processability of materials, and effective oil water separators be also developed to exhibit the optimal performance of the materials. In this mini-review, we highlight the large scale fabrication of membrane materials and the effective design of oil water separators.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.77-77
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• 2020

2019년 12월 발병한 코로나19(COVID-19)는 높은 전파력을 바탕으로 세계적으로 대유행하면서 사람들의 생명, 건강을 비롯하여 생산·소비활동까지 위협하고 있다. 코로나19는 치료제 개발 전까지 실물경제에 직접적으로 타격을 주면서 국내외 경제 전반에 악영향을 지속적으로 미칠 것으로 예상된다. 특히 외부활동 및 소비심리 위축으로 숙박, 음식, 관광, 문화, 여행 등의 대면서비스 업종의 심각한 매출 감소 및 고용악화가 발생하고 있으며, 이 외 대부분의 산업에서도 생산과 소비활동이 위축되고 있다. 이러한 소비·생산활동의 위축은 각 산업에 필요한 중간재 수요, 특히 필수재인 물이용에도 영향을 미치게 된다. 이에 본 연구에서는 코로나19 확산으로 소비가 감소할 경우 전산업과 물산업에 미치는 경제적 손실을 1년간의 모든 실물거래 관계를 행렬로 기록한 통계표인 산업연관표(input-output table)을 활용하여 분석해보았다. 이를 위해 전월대비 3월 소비자심리지수 하락 폭을 참고하여 소비 감소에 따른 시나리오 분석을 산업연관분석을 통해 실시하다. 분석결과, 5개월 동안 소비가 20% 감소하는 경우 전산업과 물산업에서 각각 48.3조원과 886억원의 생산감소가 발생하며, 부가가치는 각각 21.7조원과 451억원이 감소하는 것으로 분석되었다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.9
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• pp.1431-1438
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• 2014

This study assessed the risk and prevalence of anorexia as well as associated factors among home-dwelling elderly adults. The subjects were 419 elderly men (116) and women (303) aged 65 years and older ($76{\pm}5.6yr$) living in Korea. Data were collected by personal interviews using questionnaires. The collected data were analyzed by descriptive statistics and Pearson's correlation. The prevalence of anorexia was 35.1% among participants. Male elders (74.1%) had higher proportions of anorexia than female elders (20.1%) (P<0.001). Significant differences in the appetite were observed according to type of disease, depression, and activities of daily living (ADL) index. In the poor appetite group, central nervous system diseases were the primary illness in male elders (P<0.01), whereas endocrine diseases were the primary illness in female elders (P<0.01). Elders with good appetites had less symptoms of depression (P<0.001) and greater independence in ADL (P<0.001). These results explored the high prevalence of anorexia in geriatric populations in Korea and its impact on elderly nutritional status and health. Further research should be performed to identify the causes of anorexia and establish an intervention protocol allowing the early diagnosis of anorexia.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.233-246
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• 2020

After the COVID-19 crisis, the world's terrain has changed completely to the extent that it has been divided before and after Corona. We are living in the era of new normals, things we never thought of before Corona19, such as wearing masks everywhere, maintaining social distance, sitting on one side in the cafeteria, and online face-to-face classes. Perhaps the most seriously affected by the COVID-19 incident is the church. How should the church respond to the various problems caused by COVID-19? This study intends to re-examine the five essential missions of the church in the post-Corona19 era. The five essences are the three essential functions of the intangible church: didake (teaching), kerygma (declaration), diakonia (service), and the two essential functions of the tangible church: koinonia (association) and leiturgia (worship). Of these, koinonia and leiturgia are the most seriously threatened by the restraint of face-to-face worship in the incident of COVID-19. In times of crisis, the church needs to strengthen its vertical koinonia with God in order to perform its didake function well and increase the efficiency of the horizontal koinonia among believers. However, in the situation where face-to-face worship is desired due to social distance, teaching and proclaiming the Bible is the most important part. For this, it is considered that a specialized ministry is needed to produce high quality contents.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.1
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• pp.67-76
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• 2020

This study aims to elicit criteria regarding reassessment and designation of linear scenic sites henceforth. The results are as follows; First, based on the documents from the Cultural Properties Protection Committee of Korea, 23 out of 113 scenic sites in Korea were drawn, and their linear characteristics were categorized into four types including valleys, paths, rivers, and ridges. The linear scenic sites provide certain features in terms of sequence and direction, which results in the similar utilization among the sites which share the linear similarity. Second, the 23 sites mentioned above were intensely examined on the basis of six criteria for linear scenic sites through FGI, focus group interview. The criteria consist of six elements involving core resource(12), lot number(8), unclear(8), management path(5), ridge(4), basin(3). Third, the Cultural Heritage Administration has prioritized core resource since 2010, when designating a scenic site, whereas it tended to consider lot number as priority prior to 2010. It is thought that the authority gave consideration to issues related to private ownership of property in the scenic sites and the purpose of designation. Fourth, scenic sites are generally designated in accordance with the boundary of core resource, and in most cases, there are buffer zones alongside the core resource.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.99.2-99.2
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• 2011

Transparent conducting oxides (TCOs) supported on glass are widely used as substrates in PEC studies for photovoltaic hydrogen generation applications However, high sheet resistane ($10{\sim}15{\Omega}/cm^2$) and fragileness of glass-supported TCO substrates are the obstacles to produce the large area PEC cells. Such internal sheet resistance is detrimental to efficient collection of photogenerated majority charge carriers at the photoactive material and electrolyte interface. Moreover, these TCO substrates are very expensive and consume about 40~60% cost of the devices. Hence, a low sheet resistance of the substrate is a key point in improving the performance of PEC devices. Metallic substrates coated with a photoactive material would be a good choice for efficient charge collection. Such metal substrates based photanodes are best candidate for large-scale phtoelectrochemical water splitting for hydrogen generation. In this study, we report the enhanced PEC performance of $WO_3$ film on metal(chemical etched, bare) substrate. It is proposed that interface between $WO_3$ and the metal substrate is responsible for efficient charge transfer and demonstrated significant improvement in the photoelectrochmical performance. X-ray diffration and FESEM suduies reveled that $WO_3$ films are monoclinic, porous, polycrystalline with average grain size of ~50nm. Photocurrent of $WO_3$ prepared on metal substrates was measured in 0.5M $H_2SO_4$ electroyte under simulated $100mW/cm^2$ illumination.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.411-412
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• 2012

대부분의 상용 LED는 사파이어기판에 성장된 GaN를 기반으로 사용한다. GaN는 $1,000^{\circ}C$ 이상의 높은 온도에서 성장이 이루어지는데 이 경우 GaN과 사파이어 기판과의 높은 열팽창 계수로 인하여 compressive stress를 받게 된다. 이 compressive stress로 인하여 성장된 GaN wafer에 bowing이 일어나게 되고 이는 기판의 대면적화에 커다란 문제로 작용한다. 이런 문제들을 해결하기 위해 여러 방법이 고안되고 있지만 [1,2], 근본적으로 wafer bowing 문제의 해결은 이루어지고 있지 않다. 한편, 일반적으로 박막을 성장할 때 columnar structure를 가지는 박막이 coalescence되면 박막에 tensile stress가 걸린다는 사실이 알려져 있으며 [3], GaN를 저온에서 성장할 경우 columnar structure를 갖는다는 사실이 보고되었다 [4]. 본 연구에서는 이런columnar structure를 갖는 GaN을 이용하여 wafer bowing 문제가 해결된 GaN 박막 성장을 연구하였다. 본 실험에서는, c-plane 사파이어에 유기금속화학증착법(MOCVD)을 이용하여 nano-columnar structure를 갖는 저온 GaN layer을 성장하였다. 그 후 columnar structure를 유지하면서 $1,040^{\circ}C$까지 annealing한 후 고온에서 flat 한 GaN 박막을 nano-columnar structure GaN layer위에 성장 하였다. 우선 저온 GaN layer가 nano-columnar structure를 갖고, 고온에서도 nano-columnar structure가 유지되는 것을 scanning electron microscopy (SEM)과 transmission electron microcopy (TEM)을 통해 확인하였다. 또한 이런 columnar structure 위에 고온에서 성장시킨 flat한 GaN 박막이 성장된 것을 관찰할 수 있었다. 성장된 GaN박막의 wafer bowing 정도를 측정한 결과, columnar structure를 갖고 있는 고온 GaN 박막이 일반적인 GaN에 비해 확연하게 wafer bowing이 감소된 것을 확인할 수 있었다. Columnar structure가 coalescence가 되면서 생기는 tensile stress가 GaN박막의 성장시 발생하는 compressive stress를 compensation하여 wafer bowing이 줄어든 것으로 보인다. 본 발표에서는 이 구조에 대한 구조 및 stress 효과에 대해서 논의할 예정이다.

• Journal of the Korean Electrochemical Society
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• v.25 no.3
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• pp.119-124
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• 2022

Because high power with large size cell is used for the battery pack of hybrid electric vehicles and electric vehicles (HEV and EV), average temperature in a battery cell is the important criteria of the thermal management of the battery pack. Furthermore, fast charging technology is required to reduce battery charging time. Since battery pack performance and lifespan are deteriorated due to the heat of cells and electronic components caused by fast charging, an effective cooling system is required to reduce performance deterioration. In this study, a cooling system and module design applied to a pouch-type for fast charging battery cell are investigated, and the cooling performance that can maximize the efficiency of the battery was analyzed. The result shows that the vapor chamber cooling system has better cooling performance, the temperature drop in the module was 5.82 ℃ compared with aluminum cooling plates.