• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.488-490
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• 2012

오늘날 QoS/QoE 기술의 일환인 HTTP를 활용한 동적 적응적 스트리밍 기술이 이슈화 되고 있다. 본 논문에서는 HTTP를 활용한 동적 적응적 스트리밍 기술에 대해 연구하였다. 이를 기반으로 HTTP를 활용한 동적 적응적 스트리밍 시스템을 설계 및 구현하였다. 본 시스템에서는 MPEG2-TS 파일에 대해 비트율별 변환, 일정 시간 별 Segment의 분할, 앞에서의 파일들을 참고하여 최종적으로 전송에서 활용되는 MPD(Media Presentation Description) File의 생성과 서버와 클라이언트 간의 스트리밍에 대해 HTTP를 활용한 동적이고 적응적인 네트워크 환경에서의 비트율별 스트리머로 구성된다. 이는 불특정 다수의 네트워크 환경에서 끊김없는 지속적인 영상의 재생을 위한 다양한 스트리밍 분야와 멀티미디어 분야에 활용될 것이다.

• Asian-Australasian Journal of Animal Sciences
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• 제21권8호
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• pp.1196-1200
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• 2008

An experiment was conducted to evaluate the physiological changes of laying hens subjected to feed removal during induced molting while received probiotics in the drinking water. Post-molt performance and egg quality criteria were also studied. Ninety 78-week-old Hy-line W36 laying hens were divided into two treatment groups according to equal body weight and subjected to induced molting by continuous feed removal until around 30% BW reduction. The experiment lasted 12 wks consisting of 4-wk molting and 8-wk post-molt periods. Treatment 1 received no probiotics and was considered as the control. Treatment 2 was similar to the control except that hens received probiotics in the drinking water at 400 mg/L during feed deprivation. The results indicated that hens in both groups went out of production by Day 5. However, hens received probiotics reached 5 and 50% egg production sooner than the control (30 and 52 days vs. 31 and 54 days). Starvation during molting increased heterophil to lymphocyte (H/L) ratio, hematocrit and plasma T4 and $Na^+$ levels while plasma T3 and Cl- levels were decreased. Probiotics had no significant impact on BW reduction during molt. Post-molt egg production and egg mass were higher in hens which previously received probiotics, but these responses were not significant. However, feed conversion ratio was significantly better in hens which received probiotics. Hematocrit, plasma thyroid hormone concentrations (T3 and T4) and plasma $Na^+$, $K^+$ and Cl- levels during molting were not significantly influenced by supplementation of probiotics. However, H/L ratio showed a significant (p<0.05) reduction in birds which received probiotics suggesting beneficial effects of this product for feed-deprived laying hens. No significant difference was observed in post-molt egg quality criteria.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.867-873
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• 2001

The purpose of this study is to find analytic solution of determining the optimal capacity (lot-size) of multiproduct acyclic multistage production and inventory system to meet the finished product demand under the constraint of finite intermediate storage. Intermediate storage is a practical way to mitigate the material flow imbalance through the line of supply and demand chain. However, the cost of constructing and operating storage facilities is becoming substantial because of increasing land value, environmental and safety concern. Therefore, reasonable decision-making about the capacity of processes and storage units is an important subject for industries. The industrial solution for this subject is to use the classical economic lot sizing method, EOQ/EPQ(Economic Order Quantity/Economic Production Quantity) model, incorporated with practical experience. But EOQ/EPQ model is not suitable for the chemical plant design with highly interlinked processes and storage units because it is developed based on single product and single stage. This study overcomes the limitation of the classical lot sizing method. The superstructure of the plant consists of the network of serially and/or parallelly interlinked non-continuous processes and storage units. The processes transform a set of feedstock materials into another set of products with constant conversion factors. A novel production and inventory analysis method, PSW(Periodic Square Wave) model, is applied to describe the detail material flows among equipments. The objective function of this study is minimizing the total cost composed of setup and inventory holding cost. The advantage of PSW model comes from the fact that the model provides a set of simple analytic solutions in spite of realistic description of the material flows between processes and storage units. the resulting simple analytic solution can greatly enhance the proper and quick investment decision for the preliminary plant design problem confronted with economic situation.

• Smart Structures and Systems
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• 제20권4호
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• pp.483-498
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• 2017

Real-Time Hybrid Simulation (RTHS) is a powerful and cost-effective dynamic experimental technique. To implement a stable and accurate RTHS, time delay present in the experiment loop needs to be compensated. This delay is mostly introduced by servo-hydraulic actuator dynamics and can be reduced by applying appropriate compensators. Existing compensators have demonstrated effective performance in achieving good tracking performance. Most of them have been focused on their application in cases where the structure under investigation is subjected to inputs with relatively low frequency bandwidth such as earthquake excitations. To advance RTHS as an attractive technique for other engineering applications with broader excitation frequency, a discrete-time feedforward compensator is developed herein via various optimization techniques to enhance the performance of RTHS. The proposed compensator is unique as a discrete-time, model-based feedforward compensator. The feedforward control is chosen because it can substantially improve the reference tracking performance and speed when the plant dynamics is well-understood and modeled. The discrete-time formulation enables the use of inherently stable digital filters for compensator development, and avoids the error induced by continuous-time to discrete-time conversion during the compensator implementation in digital computer. This paper discusses the technical challenges in designing a discrete-time compensator, and proposes several optimal solutions to resolve these challenges. The effectiveness of compensators obtained via these optimal solutions is demonstrated through both numerical and experimental studies. Then, the proposed compensators have been successfully applied to RTHS tests. By comparing these results to results obtained using several existing feedforward compensators, the proposed compensator demonstrates superior performance in both time delay and Root-Mean-Square (RMS) error.

• 유기물자원화
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• 제5권1호
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• pp.1-13
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• 1997

본 연구는 음식물 찌꺼기의 사료화를 목적으로 종균제(YM, 영진환경)와 아프리카산 고온성 효모인 Kl. marxianus를 이용하여 음식물 찌꺼기를 발효시켜 보존성을 연장하기 위해 실시하였다. 6일 동안 발효시, 편성 호기적 또는 혐기적 조건보다는 2일간 호기적 조건으로 발효시킨 뒤 계속하여 4일간 혐기적으로 발효시켰을 때 유기산 생성량이 높았고 생균수도 가장 높았다. 종균제(YM)의 첨가는 무첨가 시료보다 발효 후 잔여 총 생균수를 100배 이상으로 크게 증가시켰으며 여기에 Kl. marxianus 배양액을 추가로 첨가할 경우 총생균수는 더욱 증가시켰으나 효모수를 더 증가시키지는 않았다.

• Journal of Power Electronics
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• 제15권5호
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• pp.1305-1317
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• 2015

Distributed generation systems (DGSs) have been getting more and more attention in terms of renewable energy use and new generation technologies in the past decades. The self-excited induction generator (SEIG) occupies an important role in the area of energy conversion due to its low cost, robustness and simple control. Unlike synchronous generators, the SEIG has to absorb capacitive reactive power from the outer device aiming to stabilize the terminal voltage at load changes. This paper presents a novel static VAR compensator (SVC) called a magnetic energy recovery switch (MERS) to serve as a voltage controller in SEIG powered DGSs. In addition, many small scale SEIGs, instead of a single large one, are applied and devoted to promote the generation efficiency. To begin with, an expandable mathematic model based on a d-q equivalent circuit is created for parallel SEIGs. The control method of the MERS is further improved with the objective of broadening its operating range and restraining current harmonics by parameter optimization. A hybrid control strategy is developed by taking both of the stand-alone and grid-connected modes into consideration. Then simulation and experiments are carried out in the case of single and double SEIG(s) generation. Finally, the measurement results verify that the proposed DGS with SVC-MERS achieves a better stability and higher feasibility. The major advantages of the mentioned variable reactive power supplier, when compared to the STATCOM, include the adoption of a small DC capacitor, line frequency switching, simple control and less loss.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.61.2-61.2
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• 2015

In the past decades, green energy, such as solar energy, wind power, hydropower, biomass energy, geothermal energy, and so on, has been widely investigated and developed to solve energy shortage. Recently, organic solar cells have attracted much attention, because they have many advantages, including low-cost, flexibility, light weight, and easy fabrication [1-3]. Organic solar cells are as a potential candidate of the next generation solar cells. In this abstract, to improve the power conversion efficiency and the stability, the inverted polymer solar cells with various structures were developed [4-6]. The novel cell structures included the P3HT:PCBM inverted polymer solar cells with AZO nanorods array, with pentacene-doped active layer, and with extra P3HT interfacial layer and PCBM interfacial layer. These three difference structures could respectively improve the performance of the P3HT:PCBM inverted polymer solar cells. For the inverted polymer solar cells with AZO nanorods array as the electronic transportation layer, by using the nanorod structure, the improvement of carrier collection and carrier extraction capabilities could be expected due to an increase in contact area between the nanorod array and the active layer. For the inverted polymer solar cells with pentacene-doped active layer, the hole-electron mobility in the active layer could be balanced by doping pentacene contents. The active layer with the balanced hole-electron mobility could reduce the carrier recombination in the active layers to enhance the photocurrent of the resulting inverted polymer solar cells. For the inverted polymer solar cells with extra P3HT and PCBM interfacial layers, the extra PCBM and P3HT interfacial layers could respectively improve the electron transport and hole transport. The extra PCBM interfacial layer served another function was that led more P3HT moving to the top side of the absorption layer, which reduced the non-continuous pathways of P3HT. It indicated that the recombination centers could be further reduced in the absorption layer. The extra P3HT interfacial layer could let the hole be more easily transported to the MoO3 hole transport layer. The high performance of the novel P3HT:PCBM inverted polymer solar cells with various structures were obtained.

• 디자인학연구
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• 제19권1호
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• pp.303-316
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• 2006

새로운 미의식의 창조를 위해 이질적이고 대립적인 요소를 융합 혼합하는 절충주의는 다양성, 다원화에 기초하므로서 개성화, 다양화를 추구하는 현대인의 요구에 부합되어 각광 받고 있다. 본 연구는 현대직물디자인에 표현된 절충주의 양식을 파악하기 위하여 현대예술분야를 통해 그 특성을 규명하고 이를 직물디자인에 적용시켜 새로운 경향이 제시한 미적 효과와 조형적 특성을 고찰하므로서 현대직물디자인의 변화양상을 이해하고자 하였다. 연구결과 현대 직물디자인에 나타난 경향은 다음의 3개로 구별되는데, 1) 문화적 절충에 의한 고급문화와 저급문화의 복합, 2) 시대적 절충에 의한 다양한 시대적 감각의 융합, 3) 지역적 절충에 의한 지역적 특성의 혼합으로 나타나며, 이러한 경향으로 본 직물디자인의 특징은 1) 직물디자인에 대한 시각의 전환을 가져왔고, 2) 유희적 표현을 중시하였으며 3) 다문화적 표현이 강조되고 있다. 이와 같이 직물디자인의 절충주의적 경향은 다변화되고 있는 현대 사회를 대변해주고 미래 직물디자인을 위한 하나의 가능성을 제시하여 주므로서 이에 대한 연구는 지속적으로 필요하다.

• 대한교통학회지
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• 제24권1호
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• pp.59-72
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• 2006

지속적인 교통수요관리정책의 시행에도 불구하고 서울도심지역을 비롯하여 출퇴근 시간대의 과다한 승용차 이용은 만성적인 교통혼잡의 주요 원인으로 지적되어 왔다. 본 연구에서는 대중교통 이용자 통근비용 보조제도의 시행효과를 대중교통 전환효과와 형평성 측면에서 유류비 및 주차요금 인상정책 등 타 정책수단들과 비교 분석하였다. 본 연구는 실증분석 과정의 객관성을 확보하기 위해 명시선호 분석방법론의 표준적인 절차를 따르고 있을 뿐만 아니라. 실증분석 결과의 신뢰성을 위해 표본정산방법과 비 모수 부트스트랩 방법을 적용하였다. 서울도심지역으로 출퇴근하는 직장인을 대상으로 한 실증분석 결과, 대중교통 통근비용 보조제도의 대중교통 전환효과는 유류비 인상정책과 주차요금 인상정책보다 큰 것으로 분석되었으며, 소득계층별 형평성 측면에서 주차요금 인상정책과 유류비 인상정책은 소득 역진적인 반면 대중교통 통근비용 보조제도는 소득 누진적인 성격을 갖는 것으로 분석되었다. 본 연구는 국내에서 처음으로 시도되는 대중교통 이용자 통근비용 보조제도에 관한 기초연구로서 향후 대중교통 이용 증진을 위한 대중교통 관련정책의 수립에 정량적 기초자료를 제공할 것으로 판단된다.

• 한국의상디자인학회지
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• 제19권2호
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• pp.1-14
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• 2017

The consumption trend of fashion in modern industrial society is developing from the rapid changes, and the lifespan of fashion products becomes shorter due to the various industrial wastes. Due to the attitude change caused by the ethical consumption consciousness and environment awareness, the up-cycle fashion products got to receive attention, and it is in the limelight as a new trend to realize the sustainable fashion products in the domestic and foreign fashion. The purpose of this study lies in drawing the expression characteristics by investigating and analyzing the cases of each type on the fashion bag products of up-cycle brand, and contributing to the diversification of product family fitting to the characteristics of fashion bag product of up-cycle brand, systematic strategies of up-cycle fashion products, and activation of up-cycle fashion market. In research methods, the theatrical researches were conducted centered the relevant domestic literature materials, preceding papers, etc., which ran paralleled with the actual case analysis study. Through the preceding research and websites related to selected products, websites of up-cycle companies, relevant books, related articles, etc., the expression characteristics of up-cycle fashion bag products were drawn. The results of this study are as follows: First, as it has the feature of historicality, the designs can be created by containing the designer's story, story of materials, and consumer's story. Second, since it has the characteristic of sustainability, the application of manufacturing process and materials, extension of product life, conversion of original material's function, etc. can be sustainable. Third, as it's a trait of scarcity, all products may be produced by hand, and it can have the specialty which the original materials have. Fourth, since it has an eco-friendly trait, even while saving the original materials, the aesthetic needs could be met according to the consumers' continuous demand.