• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.1-11
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• 2003

The service reliability of power plants strongly depends on the excellent performance and integrity of hydrodynamic bearings. Consequently, the bearings must be properly designed so as to control vibration amplitudes of rotor due to mass unbalance in passing critical speeds and also suppress self-excited vibrations of rotor even over maximum rated speeds. Furthermore, the bearings must be designed so as to maintain required tribological performance even under severe operating conditions. However, various tribological troubles have been experienced in power plants in Japan. The actual troubles are analysed, focusing on not only direct mechanical causes but also specific bearing designs that surfaced the troubles. Furthermore human factors that decided such designs are also studied. The powerful database of troubles and analyses will contribute greatly to designing advanced power plants with enhanced service reliability in the future. To this end, trouble information should be disclosed, shared and transferred limitlessly. Cooperation of users of power plants is essential to making more advanced design specifications, because no one has easier access to operating and trouble information of power plants than users.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1088-1090
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• 2001

In general, Power SCR(Silicon Controlled Rectifier) is most widely used in Power Plant as well as Industrial field. It has been controlled and operated according to its own control method. Especially, in case of Power plant, it plays a major role in AVR(Automatic Voltage Regulator) or electro chlorination control circuits. Generally, they used in Analog control system at above field. But each SCR current value is different because of load unbalance or switching characteristic variations, it may cause power plant unit trip or system disorder according to SCR element burn out or bad operating condition. Therefore, in this paper a development of 3 phase current balance control unit is described, it gets over the past analog control system limit, uses DSP(Digital signal processor) had high speed response, controls SCR gate firing angle for 3 phase current balance.

• Journal of the Korean Wood Science and Technology
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• 제20권3호
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• pp.39-54
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• 1992

Hollow core wood flush doors for wardrobes, and other general openings and bathroom were designed and fabricated to investigate the factors causing the bowing of them and to find out the countermeasure for the phenomena. Balance in grain orientation, thickness, specific gravity and M.C.(%) of face panel and symmetrical construction were the essential factors to prevent the deflection of flush doors just after manufacturing. Under one-sided severe service condition, the unbalance of M.C. between opposite face panels is inevitable. So the material as thick plywood with high stiffness is considered as an alternative for the stile. UF resin mixing into PVAc emulsion is preferred for bathroom.

• 한국산업정보학회논문지
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• 제7권2호
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• pp.46-53
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• 2002

본 논문에서는 공평성과 효율의 불균형의 차이를 줄이고자 DFBA(Differential Fair Buffer Allocation)의 개선된 형태인 MDFBA(Modified DFBA)를 제안한다. 제안하는 알고리즘은 총 버퍼 용량이 낮은 버퍼 한계 값 보다 작을 경우 모든 셀을 수용하여 효율을 향상시키려고 할 때 공평성과 효율의 차이를 줄여주는 알고리즘으로 시뮬레이션을 통하여 이를 확인하였다. 그리고 망의 상태에 따라 ${\gamma}$값을 다르게 적용함으로써 다양한 환경에서도 잘 적응하도록 하였다.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.117-126
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• 2009

The recent interest in sensor networks has led to a number of routing schemes that use the limited resources available at sensor nodes more efficiently. These schemes typically try to find the minimum energy path to optimize energy usage at a node. Some schemes, however, are prone to unbalance of the traffic and energy. To solve this problem, we propose a novel solution: a gradient-field approach which takes account of the minimum cost data delivery, energy consumption balancing, and traffic equalization. We also modify the backoff-based cost field setup algorithm to establish our gradient-field based sensor network and give the algorithm. Simulation results show that the overhead of routing establishment obtained by our algorithm is much less than the one obtained by Flooding. What's more, our approach guarantees the basic Quality of Service (QoS) without extra spending.

• 한국도서관정보학회지
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• 제30권4호
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• pp.137-161
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• 1999

The purpose of this study provides the conceptual and practical framework on the strategy to enhance services for the visually handicapped in the braille libraries. In order to achieve this purpose, the questionnaires, the interview, and the observation of the data collection techniques are used in the study, and the braille libraries throughout Korea which are in operation are selected as subjects for the research and survey. The results of the study are summarized as follows. 1. Most of the braille libraries, about 70%, are located in Seoul. It thus appears that this geographical unbalance cause the visually handicapped inconvenience in use, who is especially living at the regions where no braille library is located nearby. 2. To enhance the efficiency of the library services for the visually handicapped, first of all, the limited scope of the subject as well as the poor volume of the collections should be resolved as soon as possible. 3. Most of the libraries are neither equipped with necessary facilities to publish in braille nor secured the supporting instruments which facilitate to use library services for the visually handicapped satisfactorily. 4. The collections for the visually handicapped consist of the brailles and the recordings mainly. Because the visually handicapped is difficult to access and visit at the libraries alone, these materials are generally circulating rather outward by postal service than inward. 5. The qualified staff who has the very responsible position for reading and circulation is required to have educational background in library and information science, to have passions for the visually handicapped, and to have abilities to understand and translate the materials in braille.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3203-3215
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• 2015

Due to the high growth of SNS population, service scalability is one of the critical issues to be addressed. The cloud environment provides the flexible computing and storage resources for services deployment, which fits the characteristics of scalable SNS deployment. However, if the SNS related information is not properly placed, it will cause unbalance load and heavy transmission cost on the storage virtual machine (VM) and cloud data center (CDC) network. In this paper, we characterize the SNS into a graph model based on the users' associations and interest correlations. The node weight represents the degree of associations, which can be indexed by the number of friends or data sources, and the link weight denotes the correlation between users/data sources. Then, based on the SNS graph, the two-step algorithm is proposed in this paper to determine the placement of SNS related data among VMs. Two k-means based clustering schemes are proposed to allocate social data in proper VM and physical servers for pre-configured VM and dynamic VM environment, respectively. The experimental example was conducted and to illustrate and compare the performance of the proposed schemes.

• 한국화재소방학회논문지
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• 제29권5호
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• pp.79-87
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• 2015

우리나라의 소방행정력은 도심지역에 집중 배치되어 지역적 불균형을 나타내고 있는 실정이다. 모든 시민들에게 균등한 서비스가 공급되는 것이 가장 이상적인 형태이나 지역적 여건이나 예산 등과 같은 문제로 인해 이를 실현하기에는 한계가 있다. 부산시의 경우 전체 건축물의 절반가량이 구조대가 5분 이내에 도달이 어렵다는 결과가 도출되었는데, 특히 관할면적이 상대적으로 넓은 권역은 구조대의 접근성이 더욱 더 취약했다. 기존 119구조대의 접근 취약성을 평가한 결과, 현재 구조대 권역의 지리적 위치 때문에 관할 권역의 조정에 따른 개선 효과는 사실상 미비할 것으로 예측되었는데, 이에 따라 본 연구에서는 추가적인 구조대의 신설을 제시하였다. 구조대 증설을 통해 접근 취약성을 해결한 권역은 북부, 강서, 금정, 기장, 해운대 순으로 나타났는데, 해당지역 내 건축물 수는 총 53,546개소로 나타났다.

• 한국컴퓨터산업학회논문지
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• 제3권12호
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• pp.1651-1658
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• 2002

최근 들어 우리나라에서는 설치의 간편성과 높은 신뢰도를 가진 전력케이블의 사용이 증가하고 있다. 전력케이블은 출고 전에 IEEE std. 404-1993 시험을 거쳐 안정성을 확인하고 있지만 포설시 발생하는 접속부 내부의 결함으로 인하여 많은 문제가 발생하고 있다. 특히 불순물 혼입 또는 공극 발생시 고장율은 증가하게 된다. 부분방전 검출은 포설 후 전력케이블의 상태를 관측할 수 있는 유용한 방법이다. 본 연구에서는 부분방전 특성을 평가하고자 케이블 접속재인 EPR과 케이블 절연체인 XPLE 사이에 인공 결함을 발생시킨 후 데이터 취득 시스템을 이용하여 ${\varphi}$-q-n 특성을 검출하였으며, 부분방전의 정량적 해석을 위해 필요한 통계량인 최대방전전하량($q_{max}$), 평균방전 발생 펄스 수(${\={n}$), 평균 방전전하량(${\={q}$), ${\={n}$의 언밸런스 비와${\={q}$의 언밸런스 비를 계산하였다.