• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.199-208
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• 2008

최근 CMOS 이미지 센서가 저전력, 저가격, 소형화를 이루면서 이를 이용한 하드웨어 및 응용 소프트웨어 연구가 활발하게 이루어지고 있다. 하지만CMOS이미지 센서 제품들은 하드웨어에 비해 아직 응용 소프트웨어 및 펌웨어의 완성도에서 여러 가지 문제를 가진다. CMOS 이미지 센서 기반 폴링 기법은 불필요한 메시지 교환으로 인해 비효율적인 동기화 문제 및 전송 지연이 일정 수준으로 높아지면 데이터 재전송에 대한 오버헤드가 크다. 이러한 이유로 폴링 방식의 구조적 안정성(structural stability)에 문제점을 가진다. 본 논문에서는 MCU를 통한 펌웨어 기반의 고속 동기화 기법으로 폴링 주기를 세분화하여 Stepwise 동기화 기법을 제안하고, 인터럽트 방식을 적용하여 재접속 및 데이터 전송을 개선하였다. 결과적으로 제안한 기법이동기화 시간 및 에러 커넥션에서 20% 이상 뛰어난 성능을 보여주는 것으로 나타났다. 또한 CMOS 이미지 센서 기반의 C328R 보드와 저전력 MCU인 ATmega128L을 이용한 보드를 개발하고, 제공 소프트웨어와 제안된 펌웨어의 카메라 모듈과 동기화 시간 및 에러 커넥션(Error Connection) 등을 비교, 분석하였다.

• 한국진공학회지
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• 제15권2호
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• pp.180-185
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• 2006

[ $Bi_{0.5}Sb_{1.5}Te_{3}/Bi_{2}Te_{2.4}Se_{0.6}$ ]계 박막형 열전발전 소자에 의해 volt 단위의 비교적 고전압에서 microwatt 수준의 출력을 발생시킬 수 있었다. 최대 출력은 온도차와 2차 함수적인 관계가 있었고, 주어진 온도차에서 판형 모듈의 적층수에 비례하여 증가하였다. 판형 모듈의 적층수와 직렬/병렬 연결 조합의 변화에 의해 출력 전압과 전류를 조절할 수 있었다. 온도차에 대한 개회로 전압과 폐회로 전류의 변화는 직선성을 보였다. 개회로 전압은 직렬 연결의 경우 판형 모듈의 수에 의존하였지만, 병렬 연결의 경우에는 의존하지 않았다. 반면, 폐회로 전류는 직렬연결의 경우 판형 모듈의 적층수와 무관하게 일정한 값을 나타내었고, 병렬 연결의 경우 판형 모듈의 적층수에 비례하여 증가하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.281-284
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• 2007

Recently, we have developed p-i-n a-Si:H single junction thin film solar cells with RF (13.56MHz) plasma enhanced chemical vapor deposition (PECVD) system, and also successfully fabricated the mini modules ($>300cm^2$), using the laser patterning technique to form an integrated series connection. The efficiency of a mini module was 7.4% ($Area=305cm^2$, Isc=0.25A, Voc=14.74V, FF=62%). To fabricate large area modules, it is important to optimise the integrated series connection, without damaging the cell. We have newly installed the laser patterning equipment that consists of two different lasers, $SHG-YVO_4$ (${\lambda}=0.532{\mu}m$) and YAG (${\lambda}=1.064{\mu}m$). The mini-modules are formed through several scribed lines such as pattern-l (front TCO), pattern-2 (PV layers) and pattern-3 (BR/back contact). However, in the case of pattern-3, a high-energy part of laser shot damaged the textured surface of the front TCO, so that the resistance between the each cells decreases due to an incomplete isolation. In this study, the re-deposition of SnOx from the front TCO, Zn (BR layer) and Al (back contact) on the sidewalls of pattern-3 scribed lines was observed. Moreover, re-crystallization of a-Si:H layers due to thermal damage by laser patterning was evaluated. These cause an increase of a leakage current, result in a low efficiency of module. To optimize a-Si:H single junction thin film modules, a laser beam profile was changed, and its effect on isolation of scribed lines is discussed in this paper.

• 농촌계획
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• 제14권2호
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• pp.33-42
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• 2008

Recently, rural leisure by urban dwellers has been recognized as a catalyst for regional development or restoration. The federal government implemented several regional planning policies attempting to address this phenomenon in the late nineties. However, most of these policies focused on supply-centered planning, which caused a diverse set of problems relating to the sustainability and economic validity of the planning. Instead, this study focuses on the re-visitation one of the demand variables, with the intention of analyzing the character of rural leisure demand and its re-visitation choice attributes. For these reasons, this study investigates the character of current rural leisure demand, and develops functional equations about urban people who visit rural areas, using logit model. The results of this study can be summarized as follow: Urban people are visiting rural areas from nearby cities or metropolitan areas that are within 3 hours driving distance, and over 80% of rural visitors are one-day visitors. Therefore, most of their visitation activities should be understood as rural leisure, including rural tourism. In addition, the likelihood of the rural tourist to make a return visit is influenced by their transportation means, product purchasing, staying period and travel time. The results of such rural leisure demand can provide information for regional planning strategies, such as selection of target market, type of market segments, improvement of recognition level, activity program price, facility and space planning, produce sale and connection with tour site.

• 디자인학연구
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• 제13권1호
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• pp.139-148
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• 2000

디지털 기술의 발전으로 컴퓨터와 정보 통신 기술이 결합하여 하나의 시스템에서 다매체 즉 인터그레이티드 미디어(Integrated media)를 가능케 하였다. 인터그레이티드 미디어는 통합적 미디어에 의한 정보 전달방법으로 인간의 정보 전달 체계와 가장 유사한 형태로 발전되어 왔다. 따라서 인터페이스 분야에서도 형태적인 발전에 따라 인간과 컴퓨터의 상호작용(Human Computer Interaction)이라는 중요한 테마로 발전하였다. 인터페이스의 형태적 발전은 디자인 분야에서도 재정립되고 있지만 많은 분야의 동시 접목과 제품개발에 있어 체계성 부족으로 활용이 지체되고 있다. 본 연구는 MP3 자판기 개발 사례를 바탕으로 정보전달 형태 개발을 위한 요소들을 재구성함으로써 인터페이스의 새로운 모델을 구축하기 위한 시도이다. 체계적인 분류를 위하여 인터페이스를 인지적인 면과 조형적인 면을 분류하고, 하드웨어와 소프트웨어로 분류하여 누구나 쉽게 이해할 수 있도록 정립하였으며, 결과적으로 새로운 통합적 인터페이스(Integrated Interface)의 패러다임(Paradigm)을 제시함으로써 디자인의 새로운 방향 즉 통합적 아이덴티티를 구축을 위한 기본 틀을 제시하였다.

• 콘크리트학회논문집
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• 제18권1호
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• pp.135-145
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• 2006

In high multistory reinforced concrete buildings, coupled shear walls can provide an efficient structural system to resist horizontal force due to wind and seismic effects. Coupled shear walls are usually built over the whole height of the building and re laid out either as a series of walls coupled by beams and/or slabs or a central core structure with openings to accommodate doors, elevators walls, windows and corridors. A number of recent studies have focused on examining the seismic response of concrete, steel, and composite coupling beams. However, since no specific equations are available for computing the bearing strength of steel coupling beam-wall connections, it is necessary to develop such strength equations. There were carried out analytical and experimental studies to develop the strength equations of steel coupling beam-connections. Experiments were conducted to determine the factors influencing the bearing strength of the steel coupling beam-wall connection. The results of the proposed equations were in good agreement with both test results and other test data from the literature. Finally, this paper provides background for design guidelines that include a design model to calculate the bearing strength of steel coupling beam-wall connections.

• Steel and Composite Structures
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• 제5권4호
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• pp.325-340
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• 2005

This paper presents a thorough investigation into the structural performance of cold-formed steel column bases using double lipped C sections with bolted moment connections. A total of four column base tests with different connection configurations were carried out, and it was found that section failure under combined bending and shear was always critical. Moreover, the proposed column bases were demonstrated to be structurally efficient attaining moment resistances close to those of the connected sections. In order to examine the structural behaviour of the column base connections, a finite element model was established using shell and spring elements to model the sections and the bolted fastenings respectively. Both material and geometrical non-linearities were incorporated, and comparison between the test and the numerical results was presented in details. The design rules originally developed for bolted moment connections between lapped Z sections were adopted and re-formulated for the design of column base connections after careful calibration against the test data. Comparison on co-existing moments and shear forces at the critical cross-sections of the column bases was fully presented. It was shown that the proposed design and analysis method was structurally adequate to predict the failure loads under combined bending and shear for column bases with similar connection configurations.

• Steel and Composite Structures
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• 제5권4호
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• pp.289-304
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• 2005

This paper presents a thorough investigation into the structural performance of cold-formed steel column bases using double lipped C sections with bolted moment connections. A total of four column base tests with different connection configurations were carried out, and it was found that section failure under combined bending and shear was always critical. Moreover, the proposed column bases were demonstrated to be structurally efficient attaining moment resistances close to those of the connected sections. In order to examine the structural behaviour of the column base connections, a finite element model was established using shell and spring elements to model the sections and the bolted fastenings respectively. Both material and geometrical non-linearities were incorporated, and comparison between the test and the numerical results was presented in details. The design rules originally developed for bolted moment connections between lapped Z sections were adopted and re-formulated for the design of column base connections after careful calibration against the test data. Comparison on co-existing moments and shear forces at the critical cross-sections of the column bases was fully presented. It was shown that the proposed design and analysis method was structurally adequate to predict the failure loads under combined bending and shear for column bases with similar connection configurations.

• 전자공학회논문지S
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• 제34S권10호
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• pp.33-51
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• 1997

On ATM-based wired/wireless integrated network, we apply the connection re-routing method[1] which reduced the inter-cluster handoff delay by reserving VPI/VCLs for possible inter-cluster handoff calls in advance. Additionally, we propose wired resource reservation methods, which are ausiliary method and split method, for handoff QoS guarantee of various expected services. The characteristics of these methods reserve wired connection resources based on the information on the possible inter-cluster handoff calls. With mathematical analysis, we also propose each algorithm and cost function for deciding an optimal amount in reserving resources. With numberical examples, we can see that the auxiliary method effectively reduces the cost in all cases(.alpha.>.betha., .alpha.=.betha., and .alpha.<.betha.). The split method has a little cost-reduction effects, when handoffs call does not have priority over new calls (that is, .alpha..leq..betha.) and the total capacity is relatively large. In other cases, the split method, however, has effective cost-reduction effects. The numerical resutls show that these reservation methods ca flexibly cope with the time-variant environment and meet the QoS requriements on the inter-cluster handoff calls.

• 한국멀티미디어학회논문지
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• 제1권1호
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• pp.120-129
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• 1998

이동 컴퓨팅 환경은 휴대용 컴퓨터가 이동중이라도 무선 전송 링크를 통하여 네트워크 접속을 계속 유지할 수 있도록 하는 새로운 네트워크 환경이다. 이러한 환경은 컴퓨터의 이동으로 인한 네트워크 연결을 새롭게 재설정하여야 하는 문제를 포함하고 있다. 또한 그룹을 구성하는 수신자에게 메시지를 효율적으로 전달하는 멀티캐스팅 서비스가 보편화되고 있기 때문에, 이동 컴퓨팅 환경에서도 이러한 서비스를 제공하여야 한다. 본 논문에서는 이동 컴퓨팅 환경에서 효율적이고 신뢰성이 있게 멸티캐스트 패킷을 전송할 수 있는 3 계층 이동 멸티캐스팅 프로토콜을 제안하고 기존의 방볍과 비교하여 성능을 분석하였다. 우리의 방법은 핸드오프 비용과 패킷의 전달비용 변에서 기존의 방법보다 우수하였다.