• 전기의세계
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• 제26권3호
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• pp.84-91
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• 1977

A modified version of algorithm and computer program is proposed to improve the currently available contingency analysis methode for the security control of power system. The underlying principle is based upon the reasonable modification of the current methods suggested by Stagg, Tinny, Alsac, and Stott in consideration of speed, aceuracy, reliability and convergency characteristics. The algorithm and program are desirgned especially for On-Line operation, although Off-Line applications are readily available. Several case studies on the Koren Power Company's 48-bus, 91-line system have shown that the method proposed is efficiently powerful in a sense of practical applicability.

• 대한교통학회지
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• 제25권1호
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• pp.93-105
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• 2007

버스의 이용률을 높이기 위해서는 장기적으로 시설적인 측면의 투자가 필요하지만 단기적으로는 버스의 서비스 수준을 향상시켜 이용객의 만족도를 높이는 것이 효율적인 방법이다. 본 연구에서는 직무만족도가 서비스 제공수준에 영향을 미칠 것이라는 가정 하에 버스의 서비스 수준을 향상시키기 위한 방안을 제시하기 위해 버스운전기사의 직무만족도와 서비스제공수준의 관계를 분석하였다. 연구결과 버스운전기사의 직무만족도는 서비스 제공수준과 상관관계가 있으며, 직무만족 도를 높이기 위해서는 고용안정성을 높이고 투명한 경영을 통해 상벌제도와 같은 회사정책을 공정하게 하고 복지제도를 좋게 하여 성취감을 가질 수 있도록 하는 것이 필요함을 확인하였다. 또한 임금만족도를 높이는 것이 요구되는데 임금만족도는 실질임금이 높은 것을 의미하는 것이 아니라 타 회사에 대해 비교적으로 임금이 높고 임금인상에 대해 만족하는 것을 의미한다는 것을 확인하였다 따라서 적정한 인센티브제의 도입이 여러 가지 직무만족 원인요인들을 동시에 충족시킬 수 있는 하나의 방안이 될 수 있을 것이다. 직무만족도와 사고와의 관계분석을 통해 직무만족도와 사고와의 상관관계가 있음을 확인하였고 직무만족도가 그다지 높지 않더라도 휴게/편의시설이 잘 갖추어져 있을 경우 사고발생이 감소하는 경향을 확인하였다. 본 연구는 대중교통 분야의 직무만족도에 대한 실험적 연구로써 향후 이와 관련된 지속적인 연구가 이루어질 수 있는 토대를 마련하였다는 것에서 큰 의미가 있다고 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1221-1223
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• 1999

The safety loads in a nuclear power plant perform a critical function to plant safety. The design of the electrical auxiliary system should ensure the availability and adequacy of the power supply, and therefore, the frequency and voltage relaying schemes should be installed on the system to monitor and protect against the degraded system condition. If unforeseen contingencies degrade the switchyard frequency and voltage to below the minimum values, the safety related bus should properly be transferred to alternate power source. This paper presents guidelines associated with the protection of nuclear power plants during frequency/voltage decay and the steady-state and dynamic analysis of auxiliary power system that should be performed to support the degraded voltage relay(second level undervoltage relay) setting.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.72-79
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• 2005

This paper deals with the construct of e-SCM System for a supply chain of an auto-mobile company. Two first vendors and two second vendors of a bus company are included in the objects of developing e-SCM system. We analyzed the information flow and business process within vendor and between vendors by using data flow diagram, to describe process to-be model of the e-SCM system. And to analyze and design the process of the system, we used Unified Modeling Language.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.580-590
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• 2018

Active distribution system (ADS) considering distributed generation (DG) and electric vehicle (EV) is an effective way to cut carbon emission and improve system benefits. ADS is an evolving, complex and uncertain system, thus comprehensive model and effective optimization algorithms are needed. Battery swapping station (BSS) for EV service is an essential type of flexible load (FL). This paper establishes ADS planning model considering BSS firstly for the minimization of total cost including feeder investment, operation and maintenance, net loss and carbon tax. Meanwhile, immune binary firefly algorithm (IBFA) is proposed to optimize ADS planning. Firefly algorithm (FA) is a novel intelligent algorithm with simple structure and good convergence. By involving biological immune system into FA, IBFA adjusts antibody population scale to increase diversity and global search capability. To validate proposed algorithm, IBFA is compared with particle swarm optimization (PSO) algorithm on IEEE 39-bus system. The results prove that IBFA performs better than PSO in global search and convergence in ADS planning.

• 한국ITS학회 논문지
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• 제16권6호
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• pp.16-28
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• 2017

본 연구에서는 운수종사자시스템과 운행기록분석시스템을 활용하여 시내버스 고령운전자 운전적성정밀검사의 신규검사결과, 사고 및 벌점현황, 운행기록자료를 분석하였다. 분석결과 시내버스 고령운전자를 사고수가 많은 관심대상 운수회사와 관리가 잘 되고 있는 교통안전 우수회사와 비교했을 경우 운전적성정밀검사의 결과는 비슷하였으나 최근 5년 동안 운행하면서 발생한 총 벌점은 상당한 차이를 보였고 사고의 경우 평균 중상자수와 경상자의 수도 적은 것으로 확인됐다. 또한 운행 100km당 위험운전행동 횟수를 비교해보면 우수회사의 고령운전자는 다른 고령운전자와 비고령운전자와 비교해서도 위험운전행동 횟수가 상당히 적은데 잘못된 운전습관의 교정결과에 따른 것으로 나타났다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1413-1427
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• 2007

The Train Networks has a goal which requires the fast and correct data communication for distributable equipment systems. For this, in 1999, some train makers had established the standard TCN(IEC61375-1) for the inter-operating between equipment systems. Recently, TCN is being used in EU, China and the requirement to use it is growing up by many other countries more and more. The TCN was adopted at Korea High-speed Train with first in Korea, and Rotem Company finished the design of TCMS with TCN network for Istanbul EMU and KTX-2 Train and tests them. TCN(Train Communication Networks) defines the set of communication vehicle buses and train buses. The MVB(Multifunction Vehicle Bus) defines the data communication interface of equipment located in a vehicle and the WTB(Wire Train Bus) defines the data communication interface between vehicles. This paper examines whether the result of on-board test is satisfied with the IEC61375-1(International Electrotechnical Commission 61375-1) which is the international standard of TCN and introduce the results.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.170-175
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• 2003

A control algorithm is developed for highly efficient operation of auxiliary power unit (APU) that consists of a diesel engine and a directly coupled induction generator in series hybrid electric Bus (SHEB). In a series hybrid configuration the APU supplies the electric power needed for maintaining the state of charge (SOC) of the battery unit in various conditions of vehicle operation. As the rotational speed of generator does not depend on the vehicle speed, an optimized operation of engine-generator unit based on the efficiency map of each component can be achieved. The output torque of diesel engine can be controlled by the amount of fuel injection, and the power converted from mechanical to electrical energy can be adjusted by generate control unit (GCU) using the decoupling vector control of torque and flux. As for the given reference of the generating power, the multiply of speed and torque, many combinations of operating speed and torque are possible. The algorithm decides the new operating point based on the engine efficiency map and generator characteristic curve. During the transition of operating points, the speed controller saturation is avoided using variable limit and filtering of generator torque reference. A test rig and SHEB consist of a 1.5L diesel engine and a 30kw induction generator are constructed by Hyundai Motor Company.

• 산업경영시스템학회지
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• 제42권4호
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• pp.23-30
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• 2019

Automobiles are largely divided into passenger cars with less than five passengers and commercial vehicles such as construction machines, trucks, mixers, special lorries, and large buses. Automobile maintenance companies are also divided into passenger cars and commercial vehicles. Because commercial vehicles are the livelihood vehicles of individual carriers engaged in cargo transportation, passenger transportation, and construction, fast and accurate maintenance is important. Access to the expressway is also important because the car is large and uses highways. In addition, the time required for troubleshooting is long, so sufficient space must be secured for parking the vehicle, and ease of entry and exit of the vehicle in the maintenance shop should be fully considered. For this reason, commercial vehicle maintenance companies have higher initial investment costs than car maintenance companies, and it is difficult to supply and maintain maintenance personnel. Therefore, it is necessary to carefully examine and analyze various related factors for successful commercial vehicle maintenance company selection. However, most existing commercial vehicle maintenance companies often choose their location based on the empirical judgment of the founder, the customs and the case, without a clear analysis. In this study, we show how to derive the location selection factors to be considered when establishing professional maintenance company for commercial vehicles and to select the optimal location by using AHP (Analytic Hierarchy Process) method.

• 대한교통학회지
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• 제17권5호
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• pp.123-135
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• 1999

개인교통수단의 선호로 인한 자가용 승용차의 급증은 서울시의 교통혼잡을 가중시키는 주요한 요인이 되고 있다. 이러한 서울시의 교통혼잡을 완화하기 위해서는 대중교통 중심의 교통체계가 구축되어야 하며 승용차 이용자를 대중교통수단으로 유인할 수 있는 대중교통 활성화정책이 필요하다. 이러한 인식하에 버스를 이용하는 통근 및 통학목적 통행자의 버스이용횟수에 대한 개별행태모형을 통하여 버스 이용에 영향을 미치는 요인을 파악함으로써 승용차 이용자를 대중교통수단으로 유인할 수 있는 정책적인 시사점을 도출하고자 하였다. 본 연구의 목적은 일주일간 버스이용횟수 추정에 적합한 가산자료모형의 적용이다. 국내에서는 가산자료모형을 이용한 연구가 많지 않은 실정이며, 또한 모형의 설정시 과산포(overdispersion)에 대한 검정을 통하여 자료에 적합한 모형을 설정하는 것이 중요함에도 불구하고 적절한 검정없이 일반적으로 사용되고 있는 포와송 회귀모형을 주로 사용하여 왔다. 그러나 본 연구에서는 가산자료모형을 선정하기 전에 과산포에 대한 통계적인 검정을 시행한 결과 음이항 회귀모형이 본 연구의 자료에 적합한 것으로 판정되었으며, 모형설정의 중요성을 살펴보기 위하여 음이항 회귀모형을 이용하여 추정한 결과와 포와송 회귀모형을 이용하여 추정한 결과를 비교하여 보았다.