• Journal of Power Electronics
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• 제16권5호
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.681-685
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• 2008

Kromasil KR100-5CHI-TBB 칼럼을 사용하여 라세미 mandelic acid를 분리하였다. 분리도(resolution), 이론단수(number of theoretical plates), 용량인자(capacity factor)와 같은 크로마토그라피 변수들을 이동상의 조성(hexane/t-BME = 85/15 - 10/90)과 포름산 농도(0.1, 0.5, 1.0 v/v%)를 변화시켜 실험하여 계산하였다. 칼럼의 효율을 평가하기 위해 유속 대 이론단수를 비교하였다. 등온흡착식을 계산하기 위해 PIM(Pulse Input Method)을 사용하였고, mandelic acid의 농도가 0.1에서 0.3 mg/ml 사이일 때 L-과 D-mandelic acid가 각각 8.8분과 9.4분의 체류시간을 보였다. Mandelic acid의 등온흡착식은 0.3 mg/ml의 농도이하와 이동상 조성(hexane/t-BME = 75/25)에서 선형이었다. Mandelic acid의 농도가 증가할수록 mandelic acid는 비선형 거동을 보였고, Langmuir 등온흡착식은 L-과 D-mandelic acid의 경우 각각 $C_{S,L}=3.358C_{M,L}/(1+0.0897C_{M,L})$, $C_{S,D}=3.692C_{M,D}/(1+0.1457C_{M,D})$이었다.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1994년도 춘계학술대회논문집
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• pp.157-157
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• 1994

원자력발전소 운영의 중추적 역할을 담당하고 있는 운전원과 발전소시스템 사이에서 발생하는 인간공학적 요인(인적요인)은 다중방호벽의 존재와 자동화 기술의 확대에도 불구하고 원전의 가동 성 및 안전성을 위협하는 최대의 요인이다. 최근 원자력발전소 시스템에 고도화된 전자공학 및 인공 지능기술 등이 반영되고 있는 추세이나 이러한 기술의 도입이 운전원과의 복합적 상호작용관점에서 원전의 안전성과 효율성에 적합한가를 실험적으로 평가할 수 있는 실험평가기술의 확보가 필요한 실정이다. 한국원자력연구소에서는 차세대 주제어실의 설계 및 평가를 위한 실험적 자료의 생성 및 설계 대안의 평가를 위한 기술확보라는 목적을 가지고 1992년도부터 수행하고 있다. 1992년도(1차년 도)에는 새로운 주제어실에서 실험적으로 평가해야 할 평가항목을 구체화하였고, 4년간의 연구추진 내용을 설정하였다. 기존의 원자력산업계에서 요구하고 있는 인가/허가 요건, 사업자요건서, 인간 공학분야에서 제기하고 있는 문제점 등을 분석하여 10개의 실험평가항목을 도출하였으며, 실험평가 항목을 실제로 실험을 통하여 연구하기 위한 장비 및 설비 그리고 소요기술 등을 고려하여 연구방향을 설정하였다. 1993년도(2차년도)에는 차세대 주제어실의 특징을 규명하고 실험연구의 대상시스템을 설정하였다. 설정된 대상시스템을 기능별로 분석하여 설계변수를 도출하였으며, 인간공학 실험실의 구축에 필수적인 원자력발전소 시뮬레이터의 기능요건 및 실험실의 구성요건 등을 개발하고 있다. 3차년도부터는 인간공학실험을 수행하면서 자료분석체계의 개발, 원전직무 시나리오의 개발, 측정방법의 개발, 인간공학 실험실의 설계, 구축 및 검증, 평가기법 연구, 실시간 자료수집체계의 개발 등을 수행할 예정이며, 연구종료시점인 1996년도(5차년도)에는 원자력발전소 주제어실의 인간공학적 평가를 위한 실험 환경의 구축 및 실험평가기술의 확립이라는 목표가 달성된다.하는 것으로 간주된다. 2. KR 53234 10mg/kg 정맥투여후의 최고혈중농도는 1.14ug/ml, 반감기는 0.50hr, 분포용적은 2.2L이었다. 20mg/kg 경구 투여시의 최소 혈중 농도는 0.33 ug/ml, 소실반감기는 1.5시간, AUC는 0.942ug.hr/ml, 분포용적 11L, Ka는 3.05 $hr^{－1}$ 그리고 Cl는 5.3L/hr/kg이었다. 이는 KR 53170에서와 같이 매우 적은량이 흡수되고 배설되었다. 3. KR 53170의 혈청단백 결합율은 5-500 ug/ml 범위에서 78.7-86.2%이었고 KR 53234의 혈청단백결합율은 5-100 ug/ml 범위에서 79.6-71.2%이었다.이었다.tic techniques, and we have recently cloned two of the major subunits; some of the data will be presented.LIFO, 우선 순위 방식등을 선택할 수 있도록 확장하였다. SIMPLE는 자료구조 및 프로그램이 공개되어 있으므로 프로그래머가 원하는 기능을 쉽게 추가할 수 있는 장점도 있다. 아울러 SMPLE에서 새로이 추가된 자료구조와 함수 및 설비제어 방식등을 활용하여 실제 중형급 시스템에 대한 시뮬레이션 구현과 시스템 분석의 예를 보인다._3$", chain segment, with the activation energy of carriers from the shallow trap with 0.4[eV], in he amorphous regions.의 증발산율은 우기의 기상자료를 이용하여 구한 결과 0.05 - 0.10 mm/hr 의 범위로서 이로 인한 강우손실량은 큰 의미가 없음을 알았다.재발이 나타난 3례의 환자를 제외한 9례 (75%)에서는 현재까지 재발소견을 보이지 않고 있다. 이러한 결과는 다른 보고자들과 유사한 결과를 보이고 있

• Progress in Superconductivity
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• 제2권2호
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• pp.76-80
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• 2001

We have fabricated YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) ramp-edge Josephson junctions by modifying ramp edges of the base electrodes without depositing any artificial barrier layer. YBa$_2$Cu$_3$O/7-x//SrTiO$_3$ (YBCO/STO) films were deposited on SrTiO$_3$(100) by on-axis KrF laser deposition. After patterning the bottom YBCO/STO layer, the ramp edge was cleaned by ion-beam and then reacted with deionized water under various conditions prior to the deposition of counter-electrode layers. The top YBCO/STO layer was deposited and patterned by photolithography and ion milling. We measured current-voltage (I-V) characteristics, magnetic field modulation of the critical current at 77 K. Some showed resistively shunted junction (RSJ)-type I-V characteristics, while others exhibited flux-flow behaviors, depending on the dipping time of the ramp edge in deionized water. Junctions fabricated using optimized conditions showed fairly uniform distribution of junction parameters such as I$_{c}$R$_{n}$ values, which were about 0.16 mV at 77 K with 1$\sigma$~ 24%. We made a dc SQUID with the same deionized water treated junctions, and it showed the sinusoidal modulation under applied magnetic field at 77 K. 77 K.

• 한국수산과학회지
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• 제52권6호
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• pp.644-649
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• 2019

Killed vaccines, developed by inactivation with formalin, have been investigated for many fish viruses. In this study, the inactivation of viral hemorrhagic septicemia virus (VHSV) by formalin was investigated based on the infectivity titer. When viral cell culture supernatants were used, the infectivity titer decreased 1,000-fold at 1 d after treatment with 0.1% (v/v) formalin, but was below the detection limit at 7 and 14 d. Moreover, neither the N nor G gene were detectable by RT-PCR immediately after formalin treatment. In western blot analysis, N protein was not detected by rabbit antiserum against VHSV KR-9225 from 2 d after formalin treatment. On the other hand, when we used a virus that was purified and concentrated ~100 times, the infectivity titer was maintained at 10^6.05 TCID₅₀/mL, even at 14 d after formalin treatment, and no change in the viral structural proteins was observed. This study provides important data on the production and use of formalin-inactivated vaccines.

• Journal of Magnetics
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• 제7권3호
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• pp.63-71
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• 2002

Three fabrication techniques for forming thin barrier layer with uniform thickness and large barrier height in magnetic tunnel junction (MTJ) are discussed. First, the effect of immiscible element addition to Cu layer, a high conducting layer generally placed under the MTJ, is investigated in order to reduce the surface roughness of the bottom ferromagnetic layer, on which the barrier is formed. The Ag addition to the Cu layer successfully realizes the smooth surface of the ferromagnetic layer because of the suppression of the grain growth of Cu. Second, a new plasma source, characterized as low electron energy of 1 eV and high density of $10^{12}$ $cm^{-3}$, is introduced to the Al oxidation process in MTJ fabrication in order to reduce damages to the barrier layer by the ion-bombardment. The magnetotransport properties of the MTJs are investigated as a function of the annealing temperature. As a peculiar feature, the monotonous decrease of resistance area product (RA) is observed with increasing the annealing temperature. The decrease of the RA is due to the decrease of the effective barrier width. Third, the influence of the mixed inert gas species for plasma oxidization process of metallic Al layer on the tunnel magnetoresistance (TMR) was investigated. By the use of Kr-O$_2$ plasma for Al oxidation process, a 58.8 % of MR ratio was obtained at room temperature after annealing the junction at $300{^{\circ}C}$, while the achieved TMR ratio of the MTJ fabricated with usual Ar-$0_2$ plasma remained 48.4%. A faster oxidization rate of the Al layer by using Kr-O$_2$ plasma is a possible cause to prevent the over oxidization of Al layer and to realize a large magnetoresistance.

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1077-1083
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• 2012

Previously, an extracellular ${\alpha}$-amylase (BKA) had been purified from the culture of Bacillus sp. KR8104. Subsequently, the crystal structure of the active enzyme revealed a 422 amino acids polypeptide. In this study, the bka was cloned into E. coli, which encoded a polypeptide of 659 amino acids including two additional fragments: one 44 residues N-terminal fragment and another 193 residues C-terminal fragment. In order to investigate the role of the C-terminal fragment, two constructs with and without this region [$BKA{\Delta}$(N44) and $BKA{\Delta}$(N44C193)] were designed and expressed in E. coli BL21. The optimum pH, thermal stability, and the end-products of starch hydrolysis were found to be similar in both constructs. The $K_m$ and $V_{max}$ values for $BKA{\Delta}$(N44) were lower than $BKA{\Delta}$(N44C193), using either starch or ethylidene-blocked 4-nitrophenylmaltoheptaoside as a substrate.

• 미생물학회지
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• 제6권2호
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• pp.54-62
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• 1968

The effect of gamma-ray on yeast cells Sacch. cerevisiae, and the leakage of cellular constituents such as carbohydrates, ribose, amino acids, inorganic phosphates and organic phosphates have been studied. The samples of yeast cells washed throughly and starved intensively, radiation effects were compared with those of control (un-starved), the irradiation dose rates are in the range from 24 Kr. up. to 480, Kr. The loss of 260m$\mu$. absorbing material, are also observed. Mechanisms of membrane damage by gamma-irradiation are discussed corelating to permeability changes and loss of substances, then active and passive transport process are also under considerations in discussion. The experimental results are as follows, 1. Carbohydrates of yeast cell leak out by gamma-irradiation, and amounts of loss increase proportionally as the increasing of radiation dose, curve of carbohydrates loss in starved cells is parallel with those of non-starved cells. 2. Ribose leak out less than that of carbohydrate from irradiated cell, the dose response curve of loss is straight and proportional to the increasing of radiation doses, slope of the curve is much lower than of carbohydrates. 3. Amino acids also leak out and the curve of losses to radiation is not proportional, it is revealed that there are little losses from yeast at lower doses of irradiation. 4. The losses of inorganic phosphates increase unproportionally to the increasing of irradiation doses, there are little leakage at the lower doses of irradiation. The losses of organic phosphates increase proportionally to the increasing of irradiation doses, and the amount of losses are much more than that of inorganic phosphate at lower doses of irradiation. 5. Leakage from irradiated yeast cells was shown to be due to passive transport process not an energy requiring process of ion transport. 6. Loss of 260 m$\mu$. absorbing material is little more than that of control yeast by the gamma-irradiation dose of 120K.r. and 240K.r.

• 응용통계연구
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• 제25권3호
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• pp.471-483
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• 2012

One of the most important problems in cluster analysis is the selection of variables that truly define cluster structure, while eliminating noisy variables that mask such structure. Brusco and Cradit (2001) present VS-KM(variable-selection heuristic for K-means clustering) procedure for selecting true variables for K-means clustering based on adjusted Rand index. This procedure starts with the fixed number of clusters in K-means and adds variables sequentially based on an adjusted Rand index. This paper presents an updated procedure combining the VS-KM with the automated K-means procedure provided by Kim (2009). This automated variable selection procedure for K-means clustering calculates the cluster number and initial cluster center whenever new variable is added and adds a variable based on adjusted Rand index. Simulation result indicates that the proposed procedure is very effective at selecting true variables and at eliminating noisy variables. Implemented program using R can be obtained on the website "http://faculty.knou.ac.kr/sskim/nvarkm.r and vnvarkm.r".

• Steel and Composite Structures
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• 제22권6호
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• pp.1445-1463
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• 2016

The effects of moisture and temperature on buckling of laminated composite cylindrical shell panels are investigated both numerically and experimentally. A quadratic isoparametric eight-noded shell element is used in the present analysis. First order shear deformation theory is used in the present finite element formulation for buckling analysis of shell panels subjected to hygrothermal loading. A program is developed using MATLAB for parametric study on the buckling of shell panels under hygrothermal field. Benchmark results on the critical loads of hygrothermally treated woven fiber glass/epoxy laminated composite cylindrical shell panels are obtained experimentally by using universal testing machine INSTRON 8862. The effects of curvature, lamination sequences, number of layers and aspect ratios on buckling of laminated composite cylindrical curved panels subjected to hygrothermal loading are considered. The results are presented showing the reduction in buckling load of laminated composite shells with the increase in temperature and moisture concentrations.