• 한국가구학회지
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• 제27권1호
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• pp.59-68
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• 2016

The Industrial/Technological Cultural Properties are being protected, the rest facing with demolition and damages. In order to better cope with such situation, Korea has officially introduced the Registered Cultural Properties System since 2001 and began acknowledging the historical values of industrial buildings as modern cultural properties. In the Nordrhein-Westfalen, Germany, there are approximately 3,500 industrial buildings under the cultural asset protection and management not only in the Ruhr-region but also state-wide. Among these, this case study focuses on the Hansa Coking Plant, a large-scale Revitalization project to rehabilitate the old industrial complexes and facility buildings that have been shut down on December 15, 1992. Purpose of this study is to analyze main project plans of each facility in the Hansa Coking Plant and to bring out the main features of the plans, so that they can be utilized to find suggestions for Industrial/Technological Cultural Properties Revitalization in Korea.

• 한국병원경영학회지
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• 제6권1호
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• pp.147-163
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• 2001

The purpose of this study was to find out the restructuring strategy for five provincial hospitals through the business analysis and survey of the service area. Through the survey of the service area of 5 hospitals. service area was classified into three groups, such as underserved area, adequate area, and overserved area. The strategy for the restructuring the clinical departments was set up based on the result of the business analysis and characteristics of the service area. The result of the study was as follows; 1) Whether or not a provincial hospital has specialized in specific area according to the circumstances and the needs of the community was the major factor influencing on the operating result of the hospital. 2) Provincial hospitals at the underserved area has to invest according to the changes of the occupancy rate and increasing pattern of the number of patients while maintaining the status as a general hospital. 3) Provincial hospitals at the adequate area has to lower the grade from the general hospital down to the hospital first and has to upgrade the competency through the restructuring the clinical departments and investment in specific area. 4) Provincial hospitals at the overserved area has to lower the grade from the general hospital down to the hospital first and has to seek ways to change the hospital fundamentally into geriatric hospital, pneumoconiosis hospital or psychiatric hospital etc. Provincial hospitals incapable to compete with private hospitals and clinics has to lower the grade from the general hospital down to the hospital first, to specialize in specific area and to restructure some clinical departments into rental base or self-operating basis. In case such methods are judged not so good solution, provincial hospitals has to find out ways such as shut-down of several departments or operating under the attending system.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.285-290
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• 2002

Power systems are becoming larger and larger for meeting electric power demand. Therefore, the over-currents resulting from contingencies such short circuits are increasing higher. The Maximum short circuit current of modern power system is becoming so large that circuit breaker are not expected th be able to shut down the current in the future. In order to cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for future power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element(resistor or reactor). The introduction merits of the SFCL were investigated quantitatively by RTDS/EMTDC from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparison characteristics for two type SFCL. Desired design specification and operation parameters of SFCL were also given qualitatively by the performance evaluation of the two type SFCL in the power system.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.678-681
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• 2010

본 연구에서는 비정상 노즐 구동 압력비 변화가 유동장의 천이형태 및 횡력 특성에 어떠한 영향을 미치는지 조사하기 위하여 수치해석적 연구를 수행하였다. 비정상, 축대칭, 압축성 N-S 방정식을 유한 체적법으로 이산화 하였으며, SST $k-{\omega}$ 난류모델을 적용하였다. 엔진 정지 및 시동과정을 모사하기 위하여, NPR은 2~10의 범위에서 계산 하였다. 본 연구의 결과로 박리 유동과 히스테리시스 현상은 구동 압력비에 크게 의존하며, 또한 압력비 변동 시간이 횡력 특성에 지대한 영향을 미칠 수 있음을 알았다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권1호
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• pp.114-130
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• 2021

With the drastic growth of Information and Communication Technology (ICT) industry, global energy consumption is exponentially increased by mobile communications. The huge energy consumption and increased environmental awareness have triggered great interests on the research of dynamic distribution of cell user and traffic, and then designing the energy efficient cellular network. In this paper, we explore the temporal and spatial characteristics of human mobility and traffic distribution using real data set. The analysis results of cell traffic illustrate the tidal effect in temporal and spatial dimensions and obvious periodic characteristics which can be used to design Base Station (BS) dynamic with sleeping or shut-down strategy. At the same time, we designed a new Cell Zooming and BS cooperation mode. Through simulation experiments, we found that running in this mode can save about 35% of energy consumption and guarantee the required quality of service.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.587-592
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• 2018

AMOLED는 흐르는 전류에 의해 밝기가 결정되므로 AMOLED의 각 픽셀은 전류 구동 방식으로 동작하므로 AMOLED 구동을 위해서는 사용자의 요구에 의해 전류의 양을 조절할 수 있는 전원이 필요하다. 이에 본 논문에서는 사용자에 의해 설정된 전원을 공급하는 AMOLED 디스플레이용 IP의 driver 블록을 설계하고 이에 대한 시뮬레이션을 수행하였다. 설계된 IP의 driver는 전압에 대해 다이오드 전류 곡선을 가지는 AMOLED의 특성 때문에 출력 전압 레귤레이션에 중점을 두었고, low load시에는 PSM(Pulse-skipping mode)로 동작하고 medium/high load시에는 1.5MHz PWM(Pulse-width modulation) mode로 동작한다. 설계된 IP의 driver는 step-up converter의 DCM(Dis-Continue Mode)에서 발생하는 ringing 현상을 제거하도록 설계하였다. Ringing 현상은 IC내의 power switch를 파괴하거나 주위의 소자들에 EMI를 증가시키는 역할을 하게 된다. 설계된 IP의 driver에서는 ringing killer 회로를 통해 이를 최소화하였다. Mobile applications를 고려하여 disable시에는 standby current를 $1{\mu}A$이하로 설계하여 true shut-down이 가능하도록 하였다. 본 논문에서 제안한 드라이버는 AMOLED의 디스플레이용 듀얼 파워 매니지먼트회로와 같은 시스템에 효율적으로 적용할 수 있을 것으로 사료된다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.231-237
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• 2005

Interruption of good fluidization in a fluidized bed ash cooler(FBAC) for discharging bed materials such as sand or coal ash particles from the CFB combustor is frequently happened because of agglomeration of the particles in the bed. This unstable operation may, in the worst case, result in an unscheduled boiler shut down. In this study, we examined the operation problems of the FBAC of Tonghae CFB boiler and studied and introduced the simple detection and solution techniques with analyzing the mixing property and the occurrence of defluidization in a simulated fluidized bed ash cooler system (0.5m-H x 0.5m-W x 1.0m-L). The bridge of the large particles at the bed surface could be observed, and this caused to form the defluidization area at the entrance of the FBAC. The defluidization was affected not only by airflow rates but also by the particles discharging rates as well as particle size distribution in the FBAC. The local defluidization could be detected by analysis of the accumulated standard deviation error at a given period of time. Also, the regulation of the overall or local airflow rate made clearing up the local defluidization possible.

• 한국안전학회지
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• 제32권2호
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• pp.21-26
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• 2017

According to the data of Korea Occupational Safety and Health Agency, electric shock accidents during recent 11 years exceeded more than 60% in architecture/other and construction work, the countermeasures for safety are required in the harsh environment of a construction site where moving electric machines and equipments are widely used. The establishment of countermeasure for insulation degradation and defect is required, in consideration of increasing trend for accidents caused by defective insulation among low voltage electrical installation each year. The aim of this study is to propose the policy about portable electrical tool standards and/or worker's safety standards for preventing electric shock accidents on safety workings, and is to develop the technology and the safety device to prevent electric shock for accident prevention reduction through experiments. It obtained the followings through this study; statistical data analysis of late about 10 years of electric shock-related industrial accidents analysis and portable electric tools; safety device development of 'device for testing continuous grounding and power shut-down' to prevent electric shock from portable electric tools. Furthermore, developed results and proposal in this study will help to prevent the electric shock accidents from portable electric tools and will be expected the utilization of policy formulation, educational data and field supplement of the safety device, and etc.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.108-111
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• 2017

정지궤도용 우주발사체에는 고성능 상단엔진이 필수적이며 높은 비추력을 가지는 다단연소사이클 엔진이 적합하다. 터보펌프, 예연소기, 연소기, 공급계 시스템으로 구성된 9톤급 다단연소사이클 엔진 시스템의 기술검증시제를 제작하여 나로우주센터 3단 엔진 연소시험설비에서 3초 지상연소시험을 수행하였다. 엔진 시스템의 시동, 점화, 연소 및 종료가 정상적으로 수행되었으며 주요 성능 변수를 평가하였다.

• Journal of Communications and Networks
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• 제18권4호
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• pp.600-609
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• 2016

In this paper, we propose a two-stage base station (BS) sleeping scheme to save energy consumption in cellular networks. The BS sleeping mode is divided into a light sleeping stage and a deep sleeping stage according to whether there is a user in the BS's coverage. In the light sleeping stage, a BS will retain its coverage and frequently switch between the on state and the doze state according to the service characteristics. While in the deep sleeping stage analysis, the BS will shut down its coverage, and neighbor BSs will patch the coverage hole. Several closed-form formulas are derived to demonstrate the power consumption in each sleeping stage and the stage switching conditions are discussed to minimize the average power consumption. The average traffic delay caused by BS sleeping and the average deep sleeping rate under a given traffic load have also been studied. In addition, it is shown that BS sleeping is not always possible because of the limited quality of service (QoS) requirements. Simulation results show that the proposed scheme can effectively reduce the average BS power consumption, at the cost of some extra traffic delay. In summary, our proposed framework provides an essential understanding of the design of future green networks that aim to take full advantage of different stages of BS sleeping to obtain the best energy efficiency.