• Nuclear Engineering and Technology
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• 제55권3호
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• pp.801-813
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• 2023

The events at Three Mile Island in the United States brought about fundamental changes in the ways that simulation would be used in nuclear operations. The need for research simulators was identified to scientifically study human-centered risk and make recommendations for process control system designs. This paper documents the human factors research conducted at the Human Systems and Simulation Laboratory (HSSL) since its inception in 2010 at Idaho National Laboratory. The facility's primary purposes are to provide support to utilities for system upgrades and to validate modernized control room concepts. In the last decade, however, as nuclear industry needs have evolved, so too have the purposes of the HSSL. Thus, beyond control room modernization, human factors researchers have evaluated the security of nuclear infrastructure from cyber adversaries and evaluated human-in-the-loop simulations for joint operations with an integrated hydrogen generation plant. Lastly, our review presents research using human reliability analysis techniques with data collected from HSSL-based studies and concludes with potential future directions for the HSSL, including severe accident management and advanced control room technologies.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.667-672
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• 2023

This study proposes polymer electrolyte membrane fuel cell (PEMFC) based cogeneration system for greenhouse heating and cooling. The main scope of this study is to examine the proposed cogeneration system's suitability for the 660 m²-class greenhouse. A 25 kW PEMFC system generates electricity for two identical air-cooled heat pumps, each with a nominal heating capacity of 70 kW and a cooling capacity of 65 kW. Heat recovered from the fuel cell supports the heat pump, supplying hot water to the greenhouse. In cooling mode, the adsorption system provides cold water to the greenhouse using recovered heat from the fuel cell. As a result, the cogeneration system satisfies both heating and cooling capability, performing 175 and 145 kW, respectively.

• Korean Journal of Acupuncture
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• 제38권4호
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• pp.282-289
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• 2021

Objectives : The purpose of this study is to construct a model of the possible thermal runaway of electronic moxibustion and to implement an appropriate risk management method. Methods : To reproduce the system error situation of the electronic moxibustion circuit equipped with microcontroller unit, temperature sensor and heater, a code was set to disable the signal input to temperature sensor and maintain "high" heating signal to heater. The temperature change of electronic moxibustion was compared between 3 types of heater module; module 1 consisting of a combination of heater+0 ohm+0 ohm resistance, module 2 consisting of a combination of heater+Polymeric Positive Temperature Coefficient (PPTC)+0 ohm resistance, and module 3 consisting of a combination of heater+PPTC+10 ohm resistance. The temperature change was measured using a polydimethylsiloxane (PDMS) silicone phantom. After maintaining surface temperature of the phantom at 31~32℃ for 20 seconds, electronic moxibustion was applied. After operating electronic moxibustion, the temperature change was measured for 660 seconds on the surface and 900 seconds at 2 mm depth. Results : Regardless of the module type, the time-dependent change in temperature showed a rapid rise followed by a gentle curve, and a sharp drop in temperature after reaching the maximum temperature about 10 minutes after the switching the moxibustion on. Temperature measured at the depth of 2 mm below the surface increased slower and to a lesser extent. Module 1 reached highest peak temperature with largest change of temperature at both depths followed by module 2, and 3. Conclusions : Through the combination of PPTC+resistance with the heater of electronic moxibustion, it is possible to limit the rise in temperature even with the software error. Thus, this setting can be used as an independent safety measure for the electronic moxibustion control unit.

• 한국산학기술학회논문지
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• 제18권2호
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• pp.356-373
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• 2017

본 연구는 발전공기업의 성과지향보수제도가 실질적으로 직원들의 조직몰입도를 유도하여 조직의 효율성 및 조직성과 제고에 기여하는 지의 여부를 실증적으로 분석하여 공기업의 성과지향보수제도가 나아가야 할 방향을 제시해보려고 했다. 연구결과에 의하면 성과연봉제의 개인별 성과보상 적정성과 성과연봉 확정을 위한 개인별 근무평정은 조직몰입에 유의한 영향을 미치는 반면, 성과배분제의 외부평가(정부경영평가) 및 내부평가는 조직몰입에 유의한 영향을 미치지 않았다. 성과연봉제와 성과배분제 모두는 조직성과에 유의한 영향을 미치는 것으로 나타났다. 또한 성과지향보수제도 중 성과연봉제의 보상적정성 및 개인별 근무평정은 조직성과에 직접적으로 영향을 미치며, 조직몰입을 경유하여 간접적으로도 조직성과에 영향을 주어 조직몰입도의 부분적 매개효과가 있음이 검증되었으나, 외부평가와 내부평가는 조직몰입과의 영향관계가 유의하지 못하여 매개효과 검증의 의미가 없는 것으로 나타났다. 연구결과가 시사하고 있는 점은 공정하고 수용성 있는 평가지표 개발 및 성과지향 보수체계에 대한 제도운영 정책을 회사, 노조 및 직원 모두의 지혜를 모아 수립하여 시행한다면 성과지향보수제도가 회사에 대한 직원들의 애사심 고취 및 조직성과를 향상시켜 국민과 정부에게 신뢰받는 진정한 공기업으로서의 역할을 할 수 있게 된다는 것이다.

• 한국물환경학회지
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• 제18권3호
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• pp.261-270
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• 2002

The artificial aeration in the middle and the small scale reservoirs is widely used to destroy the stratified layer and algal boom. This study has been conducted at the Youncho reservoir located in Keoje island since Jan. 2000 to suggest the most suitable control strategy of the artificial aeration and reduce the side effect. The main results obtained from this research are as follows. The starting time of aeration for destratification was adjusted from the end of March to the beginning of April when the natural stratification is started. In order to prevent an anoxic condition the artificial mixing should be started by the middle of April when the DO in hypolimnion is dropped to less than $5mg/{\ell}$. The decrease DO, caused by the increase in water temperature, spreads rapidly from hypolimnion to themocline. Thermal stratification disappeared after the onset of artificial aeration within 7 days in the Yuncho reservoir. The air diffusers decrease water temperature in the layer of epilimnion and thermocline, but rise it in hypolimnion. The continuous operation of air diffuser prevent the stratification and anoxic condition in hypolimnion despite of the rising of water temperature and algal abundance. The algal abundance is not observed in effective zone by aeration. The turbidity rising problem induced from the aeration is avoided by keeping an air diffuser about 1.5m high from the bottom of lake. During the summer season, ceasing the aeration should be decided carefully. And also, it is necessary to operate the system it considering weather and temperature, and depending on the number and the position of aerators.

• 산업경영시스템학회지
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• 제46권2호
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• pp.133-142
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• 2023

The large process plant is currently implementing predictive maintenance technology to transition from the traditional Time-Based Maintenance (TBM) approach to the Condition-Based Maintenance (CBM) approach in order to improve equipment maintenance and productivity. The traditional techniques for predictive maintenance involved managing upper/lower thresholds (Set-Point) of equipment signals or identifying anomalies through control charts. Recently, with the development of techniques for big analysis, machine learning-based AAKR (Auto-Associative Kernel Regression) and deep learning-based VAE (Variation Auto-Encoder) techniques are being actively applied for predictive maintenance. However, this predictive maintenance techniques is only effective during steady-state operation of plant equipment, and it is difficult to apply them during start-up and shutdown periods when rises or falls. In addition, unlike processes such as nuclear and thermal power plants, which operate for hundreds of days after a single start-up, because the pumped power plant involves repeated start-ups and shutdowns 4-5 times a day, it is needed the prediction and alarm algorithm suitable for its characteristics. In this study, we aim to propose an approach to apply the optimal predictive alarm algorithm that is suitable for the characteristics of Pumped Storage Power Plant(PSPP) facilities to the system by analyzing the predictive maintenance techniques used in existing nuclear and coal power plants.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.179-185
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• 2014

Average temperature and temperature uniformity in a battery cell are the important criteria of the thermal management of the battery pack for hybrid electric vehicles and electric vehicles (HEVs and EVs) because high power with large size cell is used for the battery pack. Thus, liquid cooling system is generally applied for the HEV/EV battery pack. The liquid cooling system is made of multiple cooling plates with coolant flow paths. The cooling plates are inserted between the battery cells to reject the heat from batteries to coolant. In this study, the cooling plate with U-shaped coolant flow paths is considered to evaluate the effects of coolant flow condition on the cooling performance of the system. The counter flow and parallel flow set up is compared and the effect of flow rate is evaluated using CFD tool (FLUENT). The number of counter-flows and flow rate are changed and the effect on the cooling performance including average temperature, differential temperature, and standard deviation of temperature are investigated. The results show that the parallel flow has better cooling performance compared with counter flow and it is also found that the coolant flow rate should be chosen with the consideration of trade-off between the cooling performance and pressure drop.

• 한국컴퓨터정보학회논문지
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• 제19권4호
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• pp.1-8
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• 2014

멀티코어 프로세서는 여러 개의 코어가 하나의 칩에 배치됨에 따라 전력 밀도가 상승하여 높은 발열이 발생한다. 이러한 발열 문제를 해결하기 위해서 최근까지 다양한 연구가 진행되고 있다. 마이크로프로세서의 온도 감소를 위한 기법으로는 기계적 냉각 기법, 동적 온도 관리 기법 등이 있지만 이러한 기법들은 추가적인 냉각 비용이 발생하거나 성능의 저하가 발생한다. 플로어플랜기법은 추가적인 냉각비용이 발생하지 않으며, 성능저하가 거의 발생하지 않는다는 장점을 지닌다. 본 논문에서는 멀티코어 프로세서의 특정 구성요소의 발열 문제를 해결하기 위해 코어 내부 구성요소와 L2 캐쉬의 다양한 플로어플랜을 활용하고자 한다. 실험 결과, 코어의 뜨거운 구성요소를 L2 캐쉬와 인접하게 배치할 경우 칩의 온도 감소에 매우 효과적임을 알 수 있다. 코어를 캐쉬 상단-가운데 배치하는 기본 플로어플랜과 비교하여, 코어를 중앙에 배치하고 뜨거운 구성요소를 L2 캐쉬와 인접하게 배치하는 플로어플랜의 경우에는 $8.04^{\circ}C$, 코어를 외곽에 배치하고 뜨거운 구성요소를 L2 캐쉬와 인접하게 배치하는 플로어플랜의 경우에는 $8.05^{\circ}C$의 최고온도 감소 효과를 보임을 알 수 있다.

• Journal of Radiation Protection and Research
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• 제45권3호
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• pp.130-141
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• 2020

Background: Concrete activation in cyclotron vaults is a major concern associated with their decommissioning because a considerable amount of activated concrete is generated by secondary neutrons during the operation of cyclotrons. Reducing the amount of activated concrete is important because of the high cost associated with radioactive waste management. This study aims to investigate the capability of the neutron absorbing materials to reduce concrete activation. Materials and Methods: The Particle and Heavy Ion Transport code System (PHITS) code was used to simulate a cyclotron target and room. The dimensions of the room were 457 cm (length), 470 cm (width), and 320 cm (height). Gd₂O₃, B₄C, polyethylene (PE), and borated (5 wt% ^natB) PE with thicknesses of 5, 10, and 15 cm and their different combinations were selected as neutron absorbing materials. They were placed on the concrete walls to determine their effects on thermal neutrons. Thin B₄C and Gd₂O₃ were placed between the concrete wall and additional PE shield separately to decrease the required thickness of the additional shield, and the thermal neutron flux at certain depths inside the concrete was calculated for each condition. Subsequently, the optimum combination was determined with respect to radioactive waste reduction, price, and availability, and the total reduced radioactive concrete waste was estimated. Results and Discussion: In the specific conditions considered in this study, the front wall with respect to the proton beam contained radioactive waste with a depth of up to 64 cm without any additional shield. A single layer of additional shield was inefficient because a thick shield was required. Two-layer combinations comprising 0.1- or 0.4-cm-thick B₄C or Gd₂O₃ behind 10 cm-thick PE were studied to verify whether the appropriate thickness of the additional shield could be maintained. The number of transmitted thermal neutrons reduced to 30% in case of 0.1 cm-thick Gd₂O₃+10 cm-thick PE or 0.1 cm-thick B₄C+10 cm-thick PE. Thus, the thickness of the radioactive waste in the front wall was reduced from 64 to 48 cm. Conclusion: Based on price and availability, the combination of the 10 cm-thick PE+0.1 cmthick B₄C was reasonable and could effectively reduce the number of thermal neutrons. The amount of radioactive concrete waste was reduced by factor of two when considering whole concrete walls of the PET cyclotron vault.

• 한국산림과학회지
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• 제110권4호
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• pp.543-553
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• 2021

피톤치드는 식물체에서 방출되는 생물유래 휘발성유기화합물(BVOCs)에 포함되어있는 isoprene, monoterpene, sesquiterpene과 같은 화합물들 형태로 존재한다. 또한 피톤치드는 중요한 산림치유 인자인 동시에 질소화합물과 광학반응을 하여 오존 및 이차 유기에어로졸 생성에 영향을 미치는 물질로 보고되고 있다. 본 연구에서는 우리나라 도시숲 주요 30 수종을 선정하여 표준환경조건(온도: 30℃, 광도: 1,000 μmol/m²/sec)에서 400 L Tedlar bag의 순환형 챔버를 이용하여 시료를 포집하여 열탈착-GC/MS로 분석하였고, 해당 수종의 잎을 건조시켜 건중량 당 수종별 isoprene 및 terpene류의 방출량을 분석하였다. Isoprene 방출량은 전체 수종 중에서 왕대에서 가장 높았으며 졸참나무, 굴거리나무, 회양목이 주요 isoprnen 방출 수종으로 나타났다. Monoterpene 방출량은 리기다소나무에서 가장 높았으며 고로쇠, 일본잎갈나무, 백목련, 메타세쿼이아, 잣나무, 소나무, 전나무가 주요 monpterpene 방출 수종으로 나타났다. Monotrerpene 주요 물질은 α-pinene, myrcene, limonene, β-pinen, sabinene이였으며, sesquiterpene의 주요 물질은 caryophyllene, farnesene으로 나타났다. Oxygenated monoterpene의 주요 물질은 pulegone, borneol, menthol, eucalyptol, nerol이였고 oxygenated sesquiterpene에서는 carypphyllene oxide가 주요 물질로 검출되었지만 30개 수종에서 sesquiterpene과 oxygenated sesquiterpene의 방출량은 상대적으로 낮았다.