• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 봄 학술발표회논문집
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• pp.165-172
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• 1993

A non-linear mathematical model has been developed for the dynamic analysis of the reactor internals. The model includes a lumped mass and stiffness with non-linear members such as gap-spring. As hydrodynamic couplings have also been considered in the model, the effect of fluid/structure interaction between internals components due to their immersion in a confining fluid can be studied for the dynamic response analysis. The reactor internals responses for seismic and pipe break excitations have been calculated for the case of with-and without-hydrodynamic couplings.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.190-190
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• 2011

In South Korea the gross generation and heated effluent of power generation plant was 259 TWh and 4.73 billion tons in 2008. And then the waste heat from power generation was 388 TWh. It shows that the efficiency of thermal power generation plant is about 40%. Therefore to reduce $CO_2$ emission from thermal power generation plant, the energy of this heated effluent must be reused to heat buildings or farm facilities. In South Korea horticultural facilities of about 25% are heated in winter season. Total area of greenhouses which are heated is about 13,000 ha. Total heat amount needed to warm greenhouse of 13,000 ha in winter season is only 3.4% of total waste heat from power generation plant. In this study a heat pump system was designed to reuse the waste heat from power generation. Especially new heat exchanger was developed to recover the thermal energy from waste water and this model considered anti-corrosion against sea water and low cost for economic feasibility. This heat recovery system was installed in mango growing greenhouse around thermal power generation plant in Seogwipo-city, Jeju Special Self-Governing Province. The result of preliminary test shows that the heating cost of about 90% is saved as compared to boiler using tax free light oil as a fuel.

• 전자공학회논문지C
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• 제36C권5호
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• pp.38-47
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• 1999

저전력을 실현하기 위하여 구조, 논리 및 트랜지스터레벨에서 16비트 덧셈기를 설계하였다. 기존의 ELM덧셈기는 입력 비트 패턴에 의해 계산되는 블록캐리발생신호 (block carry generation signal) 때문에 특정 입력 비트 패턴이 인가되었을 때에는 G셀에서 글리치(glitch)가 발생하는 단점이 있다. 따라서 구조레벨에서는 특정 입력 비트 패턴에 대해서 글리치를 피하기 위해 자동적으로 각각의 블록캐리발생신호를 마지막 레벨의 G셀에 전달하는 저전력 덧셈기 구조를 제안하였다. 또한, 논리레벨에서는 정적 CMOS(static CMOS)논리형태와 저전력 XOR게이트로 구성된 저전력 소모에 적합한 조합형 논리형태(combination of logic style)를 사용하였다. 게다가 저전력을 위하여 트랜지스터레벨에서는 각 비트 전파의 논리깊이(logic depth)에 따라서 가변 크기 셀들(variable-sized cells)을 사용하였다. 0.6㎛ 단일폴리 삼중금속 LG CMOS 표준 공정변수를 가지고 16비트 덧셈기를 HSPICE로 모의 실험한 결과, 고정 크기 셀(fixed-sized cell)과 정적 CMOS 논리형태만으로 구성된 기존의 ELM 덧셈기에 비해 본 논문에서 제안된 덧셈기가 전력소모면에서는 23.6%, power-delay-product면에서는 22.6%의 향상을 보였다.

• 센서학회지
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• 제25권5호
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• pp.371-376
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• 2016

A self-powered piezoelectric energy harvester was developed for the application in wireless sensor node. The energy harvester was evaluated with power generation characteristics for the wireless sensor node for structural diagnosis of the electric power system. The self-powered wireless sensor node was set to measure temperature, vibration frequency of the electric power system. A piezoelectric harvester composed of 7 uni-morph cantilevers (functionalized as 6 generators and 1 vibration sensor) was connected to be an array and revealed to produce significantly high output power of approximately 10 mW at 120 Hz under 3.4 g((1 g = $9.8m/sec^2$). The wireless sensor node could work as the electric power generated by the developed piezoelectric harvester.

• International journal of advanced smart convergence
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• 제9권3호
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• pp.49-58
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• 2020

Non-orthogonal multiple access (NOMA) has been recognized as a significant technology in the fifth generation (5G) and beyond mobile communication, which encompasses the advanced smart convergence of the artificial intelligence (AI) and the internet of things (IoT). In NOMA, since the channel resources are shared by many users, it is essential to establish the user fairness. Such fairness is achieved by the power allocation among the users, and in turn, the less power is allocated to the stronger channel users. Especially, the first and second strong channel users have to share the extremely small amount of power. In this paper, we consider the power optimization for the two users with the small power. First, the closed-form expression for the power allocation is derived and then the results are validated by the numerical results. Furthermore, with the derived analytical expression, for the various channel environments, the optimal power allocation is investigated and the impact of the channel gain difference on the power allocation is analyzed.

• 동력기계공학회지
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• 제11권3호
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• pp.3-8
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• 2007

The emergency AC power supply system of the nuclear power plant is designed to supply the power to the nuclear reactor at the emergency operating condition. The safety function of the diesel generator at the nuclear power plant is to supply AC electric power to the plant safety system whenever the preferred AC power supply is unavailable. The reliable operation of onsite emergency diesel generator should be ensured by a conditioning monitoring system designed to maintain and monitor and forecast the reliability level of diesel generator. To do this kind of diesel generator condition monitoring we reviewed several operating factors and history of the wolsong unit 3 diesel generator and selected the proper conditioning monitoring operating factors.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.871-875
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• 1998

A DSP-based source current control for power conditioner is presented to compensate current harmonics and asymmetries of three-phase four-wire emergency generators caused by nonlinear and/or unbalanced loads. There-phase voltage type converter with split-dc-capacitor is adopted as the power circuit and a new direct source current control method is suggested, which simplifies the controller. The proposed control method shapes the generator current sinusoidally inphase with the voltage and allows the generator to supply maximum power even to single phase loads. An IGBT base lookVA prototype with the controller realized with a DSP (TMS320C32) is built and tested to verify the performance of the power conditioner.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.279-282
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• 2005

Recently, due to the launching of digital broadcasting service, a demand of PDP TV with large screen size is sharply rising. PDP power module is mainly divided into power factor correction (PFC) stage and sustaining power stage. Especially, sustaining power module has pulsating load characteristics. So, the hard switching at light load condition causes low efficiency and thermal problem. Therefore, a new power conversion circuit for sustaining power module of 60' PDP is proposed whose ZVS is obtained by additional ZVS tank. This paper presents properties of the proposed converter through mode analysis, numerical analysis. And a 900w prototype for sustaining power module of 60' PDP is produced to verify the analytic results. As an experimental results, ZVS is achieved from full load to 10% load variation and more than 92% of high efficiency is obtained at 10% load condition.

• 한국식품저장유통학회지
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• 제11권4호
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• pp.544-549
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• 2004

자연 유래의 미생물 효소를 이용하여 제조되는 후발효차의 주요성분과 항산화능을 조사하였다. 후발효차의 총 플라보노이드와 총 페놀 함량에서 각각 ethanol 추출물($481.4\;{\mu}g/g$, 33.5 g/100g)이 가장 높았으나, 1년 저장한 시료에서는 ethyl acetate 추출물($495.2\;{\mu}g/g$, 39.5 g/100g)이 다른 모든 추출물보다 가장 높았다. 후발효차의 catechin류는 EGC, GC, catechin, catechol 및 EGCG가 검출되었으며, 열수 추출물에서는 EGCG가 검출되지 않았다. DPPH free radical 소거능은 모든 추출물에서 그 농도가 증가할수록 활성이 증가하였는데, 저장하지 않은 후발효차와 1년간 저장한 것의 ethanol 추출물에서는 각각 $72.4\%$ 및 $80.9\%$였다. 금속 화합물 형성에 대한 환원력의 효과는 에탄올 추출물 $500\;{\mu}g/mL$에서 0.78과 0.88(1년 저장)의 환원력을 나타났고, ${\beta}$-carotene-linoleate system에서 ethyl acetate 추출물 $3000\;{\mu}g/mL$의 항산화능은 $86.6\%$와 $73.7\%$(1년 저장)를 나타내었다.

• 생명과학회지
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• 제29권2호
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• pp.231-238
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• 2019

본 연구는 사방오리 추출 분획물의 항산화 활성을 검증하기 위하여 시행되었다. 사방오리는 메탄올(MeOH) 분획에 가장 높은 총 페놀화합물($452.80{\pm}7.01{\mu}g$ gallic acid equivalents/mg)을 그리고 에틸에세테이트(EA) 분획 에 가장 높은 총 플라보노이드 함량($112.29{\pm}11.14{\mu}g$ rutin equivalents/mg)과 가장 높은 총 항산화 활성($936.23{\pm}0.07{\mu}g$ ${\alpha}$-tocopherol equivalents/mg)을 가지고 있었다. 사방오리의 용매 추출분획물에 대한 항산화 활성은 아스코빅산 등 표준 물질과 비교하여 1,1-diphenyl-2-picrylhydrazyl (DPPH) 라디칼 소거능 측정, 슈퍼옥사이드 음이온 라디칼 소거능 측정, ${\beta}$-carotene-linoleate 에세이, 환원력 측정, ferric thiocyanate법으로 지질과산화 억제력 측정 그리고 금속 킬레이팅능 측정 등 다양한 항산화 활성을 측정하였다. $250{\mu}g/ml$ 농도의 사방오리 EA와 MeOH 분획은 DPPH 라디칼 소거능 측정에서 각각 92.43와 89.20% 항산화 활성을 가지고 있었다. $50{\mu}g/ml$의 EA분획은 72.49% 슈퍼옥사이드 음이온 라디칼 소거능을 보였으며 이는 gallic acid의 소거능(60.88%)보다 조금 높았다. 또한 ${\beta}$-carotene-linoleic acid 시스템에 의한 과산화 억제능 조사에서 0.5과 1 mg/ml 농도의 EA 분획이 각각 73.45와 73.29% 억제능을 보였다. 항산화 활성은 EA 분획 > BuOH 분획 > DCM분획 > HX분획 순 이였다. 이상의 본 연구 결과에서 사방오리는 천연 항산화제제 개발을 위한 용이하게 접근 가능한 잠재적인 자원으로 판단된다.