• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 추계 학술대회논문집
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• pp.64-69
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• 2002

A numerical study has been peformed for evaluation of convection schemes for thermal hydraulic analysis in a liquid metal reactor Four convection schemes, HYBRID, QUICK, SMART and HLPA included in the CFX-4 code are considered. The performances of convection schemes are evaluated by applying them to the five test problems. The accuracy, stability and convergence are tested. It is shown that the HYBRID scheme is too diffusive, and the QUICK scheme exhibits overshoots and undershoots, and the SMART scheme shows convergence oscillations, and the HLPA scheme preserves the boundedness without causing convergence oscillations. The accuracies of SMART, QUICK and HLPA schemes are comparable. Thus, the use of HLPA scheme is highly recommended for thermal hydraulic analysis in a liquid metal reactor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.481-485
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• 1987

The fabrication of a micro mass flow sensor on a silicon chip by means of micro-machining technology is described on this paper. The operation of micro mass flow sensor is based on the heat transfer from a heated chip to a fluid. The temperature differences on the chip is a measure for the flow velocity in a plane parallel with the chip surface. An anisotropic etching technigue was used for the formation of the V-type groove in this fabrication. The micro mass flow sensor is made up of two main parts ; A thin glass plate embodying the connecting parts and mass flow sensor parts in silicon chip. This sensor have a very small size and a neglible dead space. Micro mass flow sensor can fabricate on silicon chip by micro machining technology too.

• Nuclear Engineering and Technology
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• 제35권4호
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• pp.261-273
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• 2003

The characteristics of the recirculation operation of LMR which are different from the conventional plants such as PWR and fossil fuel plants were investigated using a computer code TSGS developed in this study. For simulating the transient behavior of the steam generation system, a water level control algorithm utilizing digital control hardware features was introduced. By investigation, the function of the recirculation operation was defined, the major features of the operation were found. Also good performance of the level control algorithm was confirmed.

• Journal of Korean Neurosurgical Society
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• 제56권3호
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• pp.272-277
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• 2014

Pigmented villonodular synovitis (PVNS) is a benign proliferative joint disease with an uncertain etiology that uncommonly involves the spine. We present a case of PVNS involving the lumbar spine. A 38-year-old male developed back pain and pain in both legs caused by a mass in the L4 region of the right lamina. After gross total tumor removal, the symptoms improved. The pathological finding was synovial hyperplasia with accumulation of hemosiderin-laden macrophages. He was diagnosed with PVNS and experienced no recurrence for up to 2 years after surgery. In this report, we review the previous literature and discuss etiology, clinical manifestations, diagnosis, and treatment.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3551-3566
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• 2022

The STELLA program was launched to support the PGSFR development in 2012 and for the 2nd stage, the STELLA-2 facility was designed to investigate the integral effect of safety systems including the comprehensive interaction among PHTS, IHTS and DHRS. In STELLA-2, the long-term transient behavior after accidents can be observed and the overall safety aspect can also be evaluated. In this paper, the basic design concept from engineering basis to specific design is described. The design was aimed to meet similarity criteria and requirements based on various non-dimensional numbers and the result satisfied the key features to explain the reasoning of safety evaluation. The result of this study was used to construct the facility and the experiment is on-going. In general, the final design meets the similarity criteria of the multidimensional physics inside the reactor pool. And also, for the conservation of natural circulation phenomena, the design meets the similarity requirements of geometry and thermo-dynamic behavior.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1109-1118
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• 2021

The construction of STELLA-2 facility is on-going to demonstrate the safety system of PGSFR and to provide comprehensive understanding of transient behavior under DBEs. Considering that most events are single-phase natural circulation flow with slow transient, STELLA-2 was designed with reduced-height of 1/5 length scale. The ratio of volume to surface area in the vessel can relatively increase resulting in excessive heat transfer. Therefore, a steady-state thermal-hydraulic analysis was performed and the effect of design change to reduce the heat transfer through redan was investigated. The heat transfer through single wall redan in STELLA-2 was 3% of the core power, comparable to 1% of the core power in PGSFR. By applying the insulated redan, about 70% of decrease effect was observed. The effect on transient behavior was also evaluated. The conclusion of this study was directly applied to the STELLA-2 design and the modified version is under construction.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2010년도 춘계학술발표대회
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• pp.619-622
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• 2010

무선센서네트워크는 한정된 에너지 자원을 장기간 사용하기 위하여 주로 에너지 절약을 위한 연구에 중점을 두게 됨으로써 상대적으로 지연시간에 대한 고려는 멀어지게 되었다. 그러나 송배전 선로 등과 같이 일렬로 진행하는 설비 감시에 관한 무선센서네트워크를 구축할 경우에는 일정 구간 단위로 클러스터 헤드의 중계가 반드시 거치게 되므로 클러스터링 자체가 어렵거나 지나치게 많은 전송지연을 유발하며, 한개 노드 장애시 전체 노드에 영향을 주게 되었다. 이를 개선하기 위하여 본 논문에서는 일렬로 진행하는 소규모 클러스터의 효과적 클러스터링 방법과 Every Other Hop(EOH) 중계전송 기법을 사용하여 전송지연시간을 줄이고, Single Point of Failure 문제 해결을 가능하게 하였다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.353-363
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• 2023

The STELLA-2 is a large-scale sodium thermal-hydraulic integral effect test facility and supports the development of PGSFR. The facility adopted Pump Simulation Loop System (PSLS) concept for the mechanical sodium pump in the reference reactor to control and to measure the primary sodium flow. Since the component (mechanical pump) is replaced by the loop, it is very important to evaluate the similarity between the pump and the loop. In this paper, to simulate the characteristic of the mechanical sodium pump, the pressure loss along the various options of the loop was evaluated and the comprehensive validity of each design options was analyzed. Using the similarity criteria based on the Richardson number and Euler number conservation, the PSLS design was finalized and the result was within the acceptable error range. Finally, the result of this study was used for construction of the overall facility, STELLA-2.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3581-3590
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• 2023

High-temperature design evaluations were conducted on Type 316L stainless steel piping for a 700 ℃ large-capacity thermal energy storage verification test loop (TESET) under construction at KAERI. The hot leg piping with sodium coolant at 700 ℃ connects the main components of the loop heater, hot storage tank, and air-to-sodium heat exchanger. Currently, the design rules of ASME B31.1 and RCC-MRx provide design procedures for high-temperature piping in the creep range for Type 316L stainless steel. However, the design material properties around 700 ℃ are not available in those rules. Therefore, a number of material tests, including creep tests at various temperatures, were conducted to determine the insufficient material properties and relevant design coefficients so that high-temperature design on the 700 ℃ piping may be possible. It was shown that Type 316L stainless steel can be used in a 700 ℃ high-temperature piping system of Generation IV reactor systems or a renewable energy systems, such as thermal energy storage systems, for a limited operation time.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.1-6
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• 2008

본 연구에서는 게임에서의 몰입도 증가를 위해 기존 버튼 방식의 입력에 사용자의 자연스러운 동작을 이용한 입력과 진동 촉감을 출력하는 게임 컨트롤러를 제안한다. 동작을 이용한 입력장치는 가속도 추적기와 적외선 비디오 카메라를 동시에 사용한다. 두 정보의 장단점을 보완/융합해서 컨트롤러의 움직임을 추적하고, 사용자의 동작을 인식한다. 다양한 종류의 진동촉감은 보이스코일 진동자를 이용하여 제공된다. 또한, 제안하는 게임 컨트롤러를 게임의 상호작용에 적용하는 방법을 제공하고, 응용 프로그램에의 적용가능성을 살펴본다.