• 한국포장학회지
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• 제29권3호
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• pp.211-221
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• 2023

This study was conducted as a basic study for the selection of tags suitable for logistics management in the palletized unit-load unit and the development of various technologies to activate the palletized unit-load shipment of agricultural products through local APCs. Three types of passive RFID tags of UHF 900 MHz and one type of active RFID tag of 2.4 GHz band designed and manufactured through this study were used to analyze the receiving strength according to the tag's attachment location and distance of the palletized unit-load of agricultural products. In the passive RFID tag, there was a large difference in receiving strength by the tag's attachment location and a large amount of data loss depending on the distance within 30 m, whereas, in the active RFID tag, it was superior to the passive tags in terms of both receiving strength and data loss. Therefore, active tags are desirable from the perspective of multiple identification of warehouses with large spaces in relation to the application of RFID tags for palletized unit-loads of agricultural products, but the development of low-power technologies such as software wakeup power management as well as hardware to minimize battery power consumption is necessary.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1246-1254
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• 2018

The importance of performing Level 3 probabilistic safety assessments (PSA) along with a general interest in assessing multi-unit risk has been sharply increasing after the Fukushima Daiichi nuclear power plant (NPP) accident. However, relatively few studies on multi-unit Level 3 PSA have been performed to date, reflecting limited scenarios of multi-unit accidents with higher priority. The major difficulty to carry out a multi-unit Level 3 PSA lies in the exponentially increasing number of multi-unit accident combinations, as different source terms can be released from each NPP unit; indeed, building consequence models for the astronomical number of accident scenarios is simply impractical. In this study, a new approach has been developed that employs the look-up table method to cover every multi-unit accident scenario. Consequence results for each scenario can be found on the table, established with a practical amount of effort, and can be matched to the frequency of the scenario. Preliminary application to a six-unit NPP site was carried out, where it was found that the difference between full-coverage and cut-off cases could be considerably high and therefore influence the total risk. Additional studies should be performed to fine tune the details and overcome the limitations of the approach.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.640-646
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• 2017

T-50 계열 항공기는 비행 전 지상에서 비상동력계통 작동 점검을 위해 보조동력장치 GEN TEST를 수행하게 된다. 만일 GEN TEST 수행 중 비상동력계통에 전원이 정상적으로 공급되지 않을 경우 ECU의 응답 신호를 통해 보조동력장치가 자동으로 꺼지는 현상이 발생하게 되며, 지상에서 비상동력계통 작동 점검이 정상적으로 이루어지지 않을 경우 더 이상 비행을 할 수 없기 때문에 해당 결함은 항공기 가동률 저하에 큰 원인이 된다. ECU에서 식별된 결함코드는 인버터 결함으로 판별되었으나 인버터 교체 이후에도 동일한 결함이 지속적으로 반복되었다. 본 논문은 인버터가 특정 시간 안에 전압을 생성시키지 못 할 경우 ECU에서는 결함으로 식별되는 것이 확인되었으며, 보조/비상동력계통의, BSG, ESC, 및 ECU의 응답특성을 분석하여 개선된 방법을 제시한다. 또한, 개선된 방법에 대한 검증을 통해 비상동력계통 출력 요구시간 범위 안에 인버터 출력이 정상적으로 생성되는 것을 확인하였으며, 이를 통해 비행전 지상에서 GEN TEST 수행 시 보조동력장치 자동 꺼짐 현상을 효과적으로 예방 할 수 있음을 확인 하였다.

• 전기학회논문지
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• 제59권4호
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• pp.762-767
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• 2010

This paper describes characteristic of a light triggered thyristor investigated by experiment to adopt it into a main switch of a pulsed power unit. Triggering principle of the light triggered thyristor are referred with its structure and equivalent circuit. Operational principle and simulation result of a capacitive pulsed power circuit are explained. A variety of triggering conditions of triggering circuit and characteristics on turn-on, turn-off, voltage dividing in series operation, overvoltage protection function of the light triggered thyristor are investigated by experiments. Experimental result of 40 kJ pulsed power unit using the light triggered thyristor is presented.

• 한국수소및신에너지학회논문집
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• 제29권2호
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• pp.226-234
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• 2018

Even though the nuclear power plants has many advantages, safety issues of nuclear power plants are crucial factors of reliable operation. A tritium detector is a useful sensor to analyze amount of exposed radiation from the nuclear power plants. Currently, concentration of underwater tritium is measured precisely but it takes very long time. Since electrolysis is extracted hydrogen from the coolant of nuclear power plant, it can motivate to develop new type of real-time sensor. In this study, Proton Exchange Membrane (PEM) electrolyzer is studied for candidate as preprocessor of real-time tritium detector. Characteristics of the unit PEM electrolyzer were experimentally investigated. A simulation model is developed to understand physical behavior of unit PEM electrolyzer under dynamic operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1262-1266
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• 1999

More precise operation and control is required to ensure the stability and security of modern large power systems that is a complicated and widely dispersed structure. To ensure the precise operation and control of modern power system, most of all, precise monitoring and measurement of the various state values of power system is required. This paper discusses phasor measurement unit using synchronization signals from the GPS satellite system- Synchronized Phasor Measurement Unit. Considering the power system operation state, the transmitting data format over modems is defined. To provide all available information, PMU process the measurements to generate three phase symmetrical component. This paper proposes the transmitted data format and implements the PMU model using EMTP/Models. The validity of proposed model is confirmed through several contingency on the simple power system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1639-1641
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• 1997

In this study, We developed the 154kV optical fiber incorporated power cable which is combined optical fibers with conventional 154kV power cable. Also, we developed optical unit that optical fiber is inserted in stainless tube. The optical unit was tested, and we got good results enough to safe optical fibers. Also we put the optical fiber incorporated power cable to the test of electrical characteristics and optical characteristics, we knew that the electrical characteristics were the same characteristics as conventional 154kV power cable and the transmission loss change was almost zero. The method of optical unit connection was examined.

• 전기학회논문지
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• 제57권12호
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• pp.2285-2290
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• 2008

Even though efficiency of coal-fired power plant is proportional to operating temperature, increasement of operating temperature is limited by a technological level of each power plant component. It is an alternative plan to increase operating pressure up to ultra super critical point for efficiency enhancement. It is difficult to control process of power plant in ultra super critical point because that point has highly nonlinear characteristics. In this paper, new control logic, Unit Response Optimizer Controller(URO Controller) which is based on Fuzzy logic and Model Predictive Controller, is introduced for better performance. Then its performance is tested and analyzed with design guideline.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.116-117
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• 2013

The real time simulator for testing the high power inverter unit of a PM synchronous motor is proposed. The power converter of the real time simulator can replaces the dynamo test equipment that consists of a PMSM(PM synchronous motor) and load unit. It is verified by the simulation that the real time simulator has a similar electrical and mechanical characteristics of the PM synchronous motor.

• Korean Journal of Chemical Engineering
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• 제36권1호
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• pp.12-20
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• 2019

An energy storage system consisting of a battery and a power-to-methanol (PtM) unit was investigated to develop an energy storage system for renewable energy systems. A nonlinear programming model was established to optimize the energy storage system. The optimal installation capacities of the battery and power-to-methanol units were determined to minimize the cost of the energy system. The cost from a renewable energy system was assessed for four configurations, with or without energy storage units, of the battery and the power-to-methanol unit. The proposed model was applied to the modified electricity supply and demand based on published data. The results show that value-adding units, such as PtM, need be included to build a stable renewable energy system. This work will significantly contribute to the advancement of electricity supply and demand management and to the establishment of a nationwide policy for renewable energy storage.