• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.149-152
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• 2012

The (S)-(+)-decursin and its analogues are reported as potent inhibitors of melanin production in B16 murine melanoma cells. In order to understand the factors responsible for potency as well as inhibition of potency of (S)-(+)-decursin and its analogues, three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed. Since receptor structures are not available, a pharmacophore model was constructed. Using PHASE, we generated 3 different models and selected the seven-site model, which returned excellent statistical values ($r^2$ = 0.9127, $Q^2$ = 0.6878, Pearson-R = 0.9014). Using the generated pharmacophore model, we screened a natural products library and obtained 4'-epi-decursin as the most related compound. 4'-epidecursin is similar to (S)-(+)-decursin, but shows additional interaction possibilities with tyrosinase. The study thus sheds some light on possibility of developing more potent tyrosinase inhibitors.

• 전력전자학회논문지
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• 제18권4호
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• pp.333-341
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• 2013

In this paper, a feedback linearization control is proposed to regulate the output voltages of a three-phase four-wire inverter under the unbalanced and nonlinear load conditions. First, the nonlinear model of system including the output LC filters is derived in the d-q-0 synchronous reference frame. Then, the system is linearized by the multi-input multi-output feedback linearization. The tracking controllers for d-q-0-components of three-phase line-to-neutral load voltages are designed by linear control theory. The experimental results have shown that the proposed control method gives the good performance in response to the load conditions.

• 한국전자파학회논문지
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• 제17권8호
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• pp.767-772
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• 2006

레이다 기술의 국산화가 이슈가 되고 연구 개발에 박차를 가하고 있는 가운데 본 논문의 Dual-band 모노 펄스 수신기는 추적 레이다를 기반으로 한 실험적 수행 결과를 바탕으로 하고 있다. Dual-band 레이다를 Single-band 레이다와 비교해 보면 높은 비용과 소비 전력 등의 단점을 갖고 있지만 재밍이나 검파 거리, 이미지 신호 제거, 강우 감쇄 특성 면에서 이점을 가질 수 있다. 수신기는 X-band RF head 모듈, Ka-band RF head 모듈, 그리고 공통 IF모듈로 구성되며 X-band와 Ka-band의 각 신호는 IF 모듈의 스위칭에 의해 선택되어진다. 또한 IF모듈의 국부 신호단에서는 위상 제어기가 장착되어 합 채널을 기준으로 고각과 방위각 채널의 위상을 제어할 수 있도록 하였다. 측정 결과 전체 이득은 $40{\pm}3 dB$였으며, 송신/수신간 격리도는 39 dBc, 동적 영역 110 dB, 그리고 잡음지수는 X/Ka-band 각각 4.5dB/6.9dB로 나타났다.

• 대한환경공학회지
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• 제28권11호
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• pp.1213-1221
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• 2006

본 연구에서는 혐기성 암모늄 산화(ANAMMOX)반응을 유도하기 위해 양조폐수를 처리하는 메탄 생성 반응조의 입상 슬러지를 혐기성 반응기에 식종하였다. 암모니아성 질소($NH_4^+-N$)와 아질산성 질소($NO_2^--N$)를 1:1의 비율로 인공폐수를 조제하여 반응조를 운전하였다. 실험기간은 반응기의 유입 질소농도 조건에 따라 3개의 phase로 구분하였다. 각 phase별 유출수의 질소농도, COD, 알칼리도, 발생 가스 조성을 측정하여 처리효율을 평가하였다. Phase 1에서는 유입 $NH_4^+$-N $NO_2^-$-N를 각각 1.91 $gN/m^3{\cdot}d$부터 14.29 $gN/m^3{\cdot}d$까지 점차 높였으며 Phase 2에서 각 질소의 부하를 23.81 $gN/m^3{\cdot}d$, Phase 3에서는 19.05 $gN/m^3{\cdot}d$로 하여 운전하였다. 아질산성 질소($NO_2^-$-N)는 전 기간에 걸쳐 99%까지 제거 되었으며, 암모니아성 질소($NH_4^+-N$)의 제거율은 각 phase별로 변동폭이 높았으며 이 중 Phase 2에서 최대 75%까지 제거되었다. 한편 각 phase별 반응조의 미생물 군집 변화는 16s rDNA방법을 이용하여 분석하였다. 입상 슬러지의 접종 초기인 Phase 1의 경우 메탄생성이 일정하게 유지되었으며 메탄균과 탈질균이 공존하였다. Phase 2의 경우 아질산성 질소($NO_2^--N$)와 암모니아성 질소($NH_4^+-N$)의 제거율이 각각 99%와 75%까지 증가하였으며 이 때 ANAMMOX균의 존재가 확인되었다. Phase 3의 경우 외부 공기 유입으로 인하여 암모니아성 질소(NH4+-N)의 제거율은 급격히 감소하였으나 미생물 군집 중 여전히 ANAMMOX균이 관측되었다.

• 한국군사과학기술학회지
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• 제23권5호
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• pp.452-458
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• 2020

In this paper, the contents of the development of RESS(Radar Environmental Signals Simulator) for the test of active phased array multi-function radar are described. The developed RESS can simulate multiple target environments, such as target/jamming/missile response/cluster signals, by using received radar operational information and simulated scenario. It can also modulate frequency, phase, gain, timing on all waveforms operated by multi-function radar and simulated two targets and one jamming in the beam. The RESS can be used to perform functional and performance verification of the active phased array multi-function radar with sub-array receiving structures.

• Journal of the Optical Society of Korea
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• 제16권1호
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• pp.36-41
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• 2012

Polymethylmethacrylate powders are commonly used to improve the spreadability and blurring effects of powder foundation cosmetics. In this study, the opacity and haze effect of four types of polymethylmethacrylate powders and their 10wt% powder foundation formulation was evaluated. The distorted random hemispherical particulates with both concave and convex portions showed the highest haze and opacity value as a single powder substance. And as a formulated phase, the powder foundation formulation containing particulates with fine pores provided the highest haze and opacity value. We also examined the quantity of reflected light over the angular range $20-75^{\circ}$ by polarized light goniophotometry. The total reflected light intensity, surface-reflected light, and internally reflected light were characterized. These studies demonstrated that hemispherical PMMA powders produce natural brilliance by creating high internally reflected light which is similar to the total reflection profile of artificial skin.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2578-2580
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• 1999

In this paper, an embedded micro processor based resistance spot welding controller is introduced which has been recently developed by Hyosung Co. Ltd. The performance of rapid and constant high current control is tested experimentally. This paper shows configurations of measuring system for high current and realtime RMS conversion techniques of sampled discrete data. A digital proportional control is adopted for this system and the result shows that this new product is working well at wide range of welding current and the performance is improved compared with some other commercially available controllers that are widely used in our industries. User friendly MMI system and a computer network system to monitor each welding processes are also presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2110-2112
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• 1997

The induction motor drive for the spindle of machining center is required to do not only a constant torque operation in low speed region(below base rpm), but also a constant power operation in high speed region(beyond base rpm). Also, control voltage shortage due to high speed operation must be overcome. The vector controlled inverter system with input 3 phase pwm converter is designed for that kind of condition. We experimented the performance of the inverter system with spindle motor made by Hyosung industries co.

• 한국시스템다이내믹스연구
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• 제5권2호
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• pp.125-147
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• 2004

System dynamics model has been developed and computer simulation has been peformed for the evaluation of R&D policy. One of the main results of the basecase scenario is as follows. After simulation of nuclear R&D resource allocation strategies, we discovered that their net benefit value was maximum at 130% nuclear R&D budget case. And after simulation of human resource management strategies and policy research program strategies, we confirmed that it is beneficial to allocate budgets in the early phase for human resources management program and research program for the policy.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 추계학술발표대회논문집 제23권 2호
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• pp.283-286
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• 2004

Due to advances in electronics very high quality audio reproduction is today possible. But the listening environment causes deviation of the audio system from the expected behavior. Firstly the listening Room significantly changes the audio signal frequencies and their phase. Secondly the position of the user in the room affects the perceived sound. With existing DSP technology it is possible to adequately correct these effects. In our work we developed a room correction system, correcting up to 7.1 channels using dual Motorola 56367 fixed point DSP's, implementing position dependent room effects measurement, real time compensation filter design and equalization filtering procedures.