• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.2
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• pp.174-180
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• 2004

If Fiber Reinforced Metal Laminates(FRMLs) were delaminated, the decrease of stiffness and fiber bridging effect would result in the sudden aggravation of fatigue characteristics. It was reported that the delamination of FRMLs resulted from the crack of metal layers and that it depended on the crack growth. While cracks were made in FRMLs containing a saw-cuts under fatigue loading, cracks could be produced or not in FRMLs with circular holes under the same condition. When the FRMLs with the circular holes produce not the crack but the delamination, it is not possible to analyze it by the conventional fracture parameters expressed as the function of the crack. And so, this research suggests a new analytical model of the delamination to make the comparison of the delamination behavior possible whenever the cracks occur or not. Therefore, a new analytical model called Pseudo Crack Model(PCM) was suggested to compare the delaminations whether cracks were made or not. The relationship between the crack energy consumption rate( $E_{crack}$) and the delamination energy consumption rate( $E_{del}$) was discussed and it was also known that the effect of $E_{del}$ was larger than that of $E_{crack}$.

• The KIPS Transactions:PartA
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• v.19A no.3
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• pp.139-146
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• 2012

In the server cluster environment, one of the ways saving energy is to control server's power according to traffic conditions. This is to determine the ON/OFF state of servers according to energy usage of data center and each server. To do this, we need a way to estimate each server's energy. In this paper, we use a software-based power consumption estimation model because it is more efficient than the hardware model using power meter in terms of energy and cost. The traditional software-based power consumption estimation model has a drawback in that it doesn't know well the computing status of servers because it uses only the idle status field of CPU. Therefore it doesn't estimate consumption power effectively. In this paper, we present a CPU field based power consumption estimation model to estimate more accurate than the two traditional models (CPU/Disk/Memory utilization based power consumption estimation model and CPU idle utilization based power consumption estimation model) by using the various status fields of CPU to get the CPU status of servers and the overall status of system. We performed experiments using 2 PCs and compared the power consumption estimated by the power consumption model (software) with that measured by the power meter (hardware). The experimental results show that the traditional model has about 8-15% average error rate but our proposed model has about 2% average error rate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.171-179
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• 2013

The thermodynamic characteristics of a combined cycle applied with a topping cycle such as a trilateral cycle at relatively high temperatures and a bottoming cycle such as an organic Rankine cycle at relatively low temperatures have been theoretically investigated. This is an electric generation system used to recover the waste heat of the exhaust gas from a diesel engine used for the propulsion of a large ship. As a result, when the boundary temperature between the topping and the bottoming cycles increased, the system efficiencies of energy and exergy were simultaneously maximized because the total exergy destruction rate (${\sum}\dot{E}_d$) and exergy loss ($\dot{E}_{out2}$) decreased, respectively. In the case of a marine diesel engine, the waste heat recovery electric generation system can be utilized for additional propulsion power, and the propulsion efficiency was found to be improved by an average of 9.17 % according to the engine load variation, as compared to the case with only the base engine. In this case, the specific fuel consumption and specific $CO_2$ emission of the diesel engine were reduced by an average of 8.4% and 8.37%, respectively.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.158-158
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• 2016

최근 화석연료의 고갈과 환경 보전 및 에너지 절약에 대한 관심이 높아짐에 따라 화석연료의 소비를 최소화하고 실내조건을 쾌적하게 유지하려는 연구가 진행되고 있다. 국내의 경우 전체 에너지 소비의 30%이상을 차지하고 있는 건물부문에서의 에너지 소비를 줄이기 위한 활발한 연구가 진행되고 있으며 이에 따른 에너지절약 소재개발이 활발하게 진행되고 있다. 1975년 이후 여러 차례에 걸친 단열강화 조치를 통해 건물에서의 에너지 소모를 줄이고 있었으나 건물의 외벽에 대한 사항으로 한정되어있었고, 또한 건물의 창 면적이 증가함에 따라 창을 통한 열손실량과 열획득량이 더욱 증가하게 되었다. 이러한 문제를 해결하기 위해 열반사유리에 대한 많은 연구가 진행되고 있다. 열반사유리는 근적외선(열선)영역의 빛을 반사시켜 실내의 열손실량 및 외부에서의 열획득량을 감소시켜 에너지의 소비를 줄일 수 있는 유리을 말한다. 이러한 열반사유리은 fresnel 방정식을 통해 빛의 파장대에 따른 반사율 및 투과도를 예측할 수 있는데, 다층박막구조인 Oxide-Metal-Oxide(OMO)구조는 Oxide의 높은 굴절률과 Metal의 낮은 굴절률을 통해 가시광영역대의 높은 투과도와 근적외선 영역의 높은 반사율을 얻을 수 있다. 또한 Metal층을 삽입함으로서 flexible한 코팅이 가능하고, 높은 carrier density와 mobility로 표면 플라즈몬 공명을 통해 특정 파장대의 반사율을 높일 수 있으므로 많은 연구가 진행되고 있다. $TiO_2$는 고굴절률 및 낮은 광흡수성의 특성을 가지는 산화물반도체로 기존의 $In_2O_3$계 산화물에 비해 값이 싸고 높은 안정성과 광촉매특성을 보이므로 외부에 노출된 환경에 적합한 재료이다. Ag는 저굴절률과 낮은 광흡수성을 가지는 재료로 금속층에 적합하다. 본 연구에서는 fresnel 방정식을 통해 반사도 및 투과도를 예측하고 마그네트론 스퍼터링법으로 다층박막을 열선인 적외선 영역에서의 반사율 및 반사 효율을 평가하였다. Index-matching 시뮬레이션을 통해 $TiO_2/Ag/TiO_2$ 다층박막의 투과도와 반사도를 이론적으로 검토하였다. 시뮬레이션 프로그램은 Macleod프로그램을 이용하였고 재료 각각의 굴절률은 Ellipsometry를 이용하여 측정하였다. 두께 40 nm 와 8 ~ 16 nm를 가지는 $TiO_2$층과 Ag층을 각각 RF/DC 마그네트론 스퍼터링법을 이용하여 Glass기판 위에 증착하였다. 직경 3 in 의 $TiO_2$, Ag 소결체 타깃을 이용하였고 스퍼터링 파워는 각각 200 W, 50 W로 설정하였고, 스퍼터링 가스는 Ar가스의 유량을 20 sccm으로 설정하였다. 작업압력은 모두 1 Pa로 설정하였고 타깃 표면의 불순물 및 이물질 제거를 위해 Pre-sputtering을 10분 진행하였다. 박막의 두께는 reflectometer와 Alphastep을 이용하여 측정하였고 Hall effect measurement를 이용하여 비저항, carrier density, mobility등 전기적 특성을 측정하였다. 또한 UV-VIS spectrometer와 USPM-RU-W NIR Micro-Spectrophotometer를 통해 광학적 특성을 측정하였고 계산 값과 비교분석하였다. 또한 열반사 특성을 평가하기 위해 직접 set-up한 장비를 이용하였다. 단열 박스에 샘플을 장착해 적외선 램프를 조사하였을 때의 열 반사효율을 평가하였고, IR Camera를 이용하여 단열 박스 내부의 온도 변화를 관찰하였다.

• Korea journal of population studies
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• v.26 no.1
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• pp.79-113
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• 2003

This study is intended to explore an income level necessart for the old-age by income Status. Firstly, it is verified whether there is significant difference between old-age and working age or not. Secondly, if their difference is found, it will be identified that it is determined by certain factors. Thirdly, it is brought out needful income level for the old-age living through analysing old-age consumption expenditure level over working age. The results in this research are as follows. Firstly, there is a significant difference between old-age and working age. Secondly, the major factors which generated difference between old-age and working age consumption expenditure are income, household size, and age. Thirdly, the income level necessary for oldage living is on average 61 %. By income status, it is 90-100% for low income status, 60-70% for middle income status, 50-60% for high income status.

• KDI Journal of Economic Policy
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• v.10 no.3
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• pp.29-49
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• 1988

본(本) 연구(硏究)는 Tobin의 q-이론(理論)에 입각하여 투자(投資)를 결정하고 동태적(動態的) 예산제약하(豫算制約下)에서의 외채지불능력(外債支拂能力)만을 감안한 적정소비결정(滴定消費決定)의 문제점을 논의하는 동시에 우리나라에 있어서 자본(資本)의 시장가치(市場價値), 자본(資本)의 한계생산력(限界生産力) 및 이자율간(利資率間)의 관계를 살펴보고자 함에 목적(目的)이 있다. Balassa and Williamson(1987)은 우리나라의 자본수익률(資本收益率)이 해외차입금리(海外借入金利)보다 높으므로 투자(投資)를 확대시키는 한편, 지금과 같이 호전(好轉)된 해외여건(海外與件)이 상당기간 지속(持續)될 것이며 우리나라의 신인도(信認度)가 높다는 점을 들어 소비(消費)를 확대하고 장기적으로 10억(億)~20억(億)달러의 경상수지적자(經常收支赤子)를 유지하는 것이 바람직하다고 주장하였다. 본고(本稿)는 그들의 주장(主張)을 수용(受容)하는 소비(消費)와 투자(投資)의 동태적(動態的) 최적배분(最適配分)에 관한 단순모형(單純模型)을 구축하여 그들의 주장(主張)을 계량적(計量的)으로 보다 엄밀하게 점검하는 한편, 1990년대 초에 순채권국(純債權國)이 되려는 6차계획(次計劃)의 기본방향(基本方向)이 우리나라의 과거경험(過去經驗) 및 대내외여건전망(對內外與件展望)에 비추어 타당함을 보이려고 하였다.

• Environmental and Resource Economics Review
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• v.5 no.1
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• pp.41-66
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• 1995

본 논문은 전력수요와 내구재의 구매를 결정하는 과정을 모형화하고 소득효과를 추정해 보기 위한 것이다. 효용극대화 원리에 기초하여 개인의 의사결정과 관련된 동시성을 규명하고, 이를 논리적으로 설명할 수 있는 모형을 설정함으로써 전력소비와 관련된 보다 정밀한 정보를 얻을 수 있음을 보이고 있다. 소득효과를 추정하는데 있어서 소득이 소비에 주는 영향을 단기와 장기로 나누어 추정한다. 단기의 경우에는 내구재 보유수준이 정해져 있기 때문에 이용율만 상승한다. 그러나 어느 정도 시간이 지나면 효용을 극대화하기 위하여 내구재 보유수준을 높이고 이에 따라 소비수준이 더 늘어나게 된다는 가설을 미시자료(micro data)를 통해 실증적으로 분석한다. 소득효과는 계절별로, 그리고 소득계층별로 보이는 다양한 분포를 추정한다.

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.7-14
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• 2016

Recently, as cloud computing technologies are developed, it enable to work anytime and anywhere by smart phone and computer. Also, cloud computing technologies are suited to reduce costs of maintaining IT infrastructure and initial investment, so cloud computing has been developed. As demand about cloud computing has risen sharply, problems of power consumption are occurred to maintain the environment of data center. To solve the problem, first of all, power consumption has been measured. Although using power meter to measure power consumption obtain accurate power consumption, extra cost is incurred. Thus, we propose prediction method about power consumption without power meter. To proving accuracy about proposed method, we perform CPU and Hard disk test on cloud computing environment. During the tests, we obtain both predictive value by proposed method and actual value by power meter, and we calculate error rate. As a result, error rate of predictive value and actual value shows about 4.22% in CPU test and about 8.51% in Hard disk test.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.2
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• pp.83-100
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• 2022

In marketing, the thematic conceptual study related to hedonic consumption with product symbolism contributed to symbolic consumerism and its hedonic experience. Researching how consumers deal with expectations for unexpected income or windfall gains helps understand what makes them enjoy experiences. This paper discusses the trade-off relationship between hedonic and utilitarian consumption. it aims to determine when and why people choose hedonic (pleasant) or utilitarian (material) products under windfall gains. We suggested five hypotheses, and through a series of experiments, respondents preferred hedonic to utilitarian goods when lottery amounts increased and the probabilities did not discriminate between two products. the preference order was not discriminated in the hedonic, utilitarian goods. the shape of preference revealed an opposite direction (U vs. invert-U)when the winfall amounts increased. and when the discounting rates varied, the consumers' preference order was expected to change. Subjects selected hedonic goods the most, utilitarian goods second, and cash rewards were the last choice. Therefore, stimulating consumers' hedonism and promoting hedonic experiences might be effective marketing tactics and strategies.

• Journal of Korea Society of Industrial Information Systems
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• v.9 no.3
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• pp.1-10
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• 2004

Video-On-Demand servers use compression techniques to reduce the storage and bandwidth requirements. The compression techniques make the bit rates of compressed video data significantly variable from frame to frame. Consequently, Video-On-Demand servers with a constant bit rate retrieval can not maximize the utilization of resources. It is possible that when variable bit rate video data is stored, accurate description of the bit rate changes could be computed a priori. In this paper, I propose a buffer management scheme called MAX for Video-On-Demand server using variable bit rate continuous media. By caching and prefetching the data, MAX buffer management scheme reduces the variation of the compressed data and increases the number of clients simultaneously served and maximizes the utilization of system resources. Results of trace-driven simulations show the effectiveness of the scheme.