• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.155-156
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• 2015

This paper proposes a high efficiency wireless power transfer system with an asymmetric 4-coil resonator. It presents a theoretical analysis, an optimal design method, and experimental results. In the proposed asymmetric 4-coil system, the primary side consists of a source coil and two transmitter coils which are called intermediate coils, and in the secondary side, a load coil serves as a receiver coil. In the primary side, two intermediate coils boost the apparent coupling coefficient at around the operating frequency. Because of this double boosting effect, the system with an asymmetric 4-coil resonator has a higher efficiency than the conventional symmetric 4-coil system. The prototype operates at 90 kHz ofswitching frequency and has 200 mm of the power transmission distance between the primary side and the secondary side. An AC-DC overall system efficiency of 96.56% has been achieved at 3.3 kW of output power.

• Advances in materials Research
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• 제8권1호
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• pp.1-10
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• 2019

Roll bonding (RB) process of bi-metal laminates as a new noble method of bonding has been widely used in the production of bimetal laminates. In the present study, asymmetric roll bonding process as a new noble method has been presented to produce Al/Cu bimetallic laminates with the thickness reduction ratios 10%, 20% and 30% together with mismatch rolling diameter ($\frac{R_2}{R_1}$) ratio 1:1, 1:1.1 and 1:1.2. ABAQUS as a finite element simulation software was used to model the deformation of samples. The main attention in this study focuses on the bonding properties of Al/Cu samples. The effect of the $\frac{R_2}{R_1}$ ratios was investigated to improve the bond strength. During the simulation, for samples produced with $\frac{R_2}{R_1}=1:1.2$, the vertical plastic strain of samples was reach the maximum value with a high quality bond. Moreover, the peeling surface of samples after the peeling test was investigated by the scanning electron microscopy (SEM).

• Bulletin of the Korean Chemical Society
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• 제8권4호
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• pp.276-280
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• 1987

Several chiral potassium B-alkyl-9-boratabicyclo[3.3.1]nonanes $(K\; B-R^*-9-BBNH)$ and potassium B-alkoxy-9-boratabicyclo[3.3.1]nonanes $(K \;B-OR^*-9-BBNH)$ were synthesized by treatment of the corresponding trialkylboranes and dialkylmonoalkoxyboranes with a small excess of potassium hydride. The chiral B-alkoxy derivatives generally reduce representative ketones, such as acetophenone and 3-methyl-2-butanone, with greater optical induction than the corresponding B-alkyl derivatives, suggesting the involvement of the oxygen atom in the control process for asymmetric synthesis.

• 한국입자에어로졸학회지
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• 제10권1호
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• pp.27-31
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• 2014

A simple bimodal model has been developed to analyze charged particle coagulation by modifying previously suggested bimdal model for evolution of particle generation and growth. In the present model, two monodisperse modes are used and 40 charge nodes are assigned to each mode to account both change of the particle size and charge distribution. In addition, we also implemented the effect of electrostatic dispersion loss in the present model. Based on the developed model, we analyzed coagulation of asymmetric bipolar charged particles by computing evolutions of particle number concentration, geometric mean diameter of particles, charge asymmetric ratio and geometric standard deviation of particle size distribution for various initial charge asymmetric ratios. The number concentration of asymmetric bipolar charged particles decreases faster than that of neutral particles but that does not give faster growth of particles since the electrostatic dispersion loss overwhelms particle growth by coagulation.

• 한국소음진동공학회논문집
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• 제20권10호
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• pp.915-922
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• 2010

This paper presents an efficient method for determining the forced response of a spinning flexible disk-spindle system supported by fluid dynamic bearings(FDBs) in a computer hard disk drive(HDD). The spinning flexible disk-spindle system is represented by the asymmetric finite element equations of motion originating from the asymmetric dynamic coefficients of the FDBs and the gyroscopic moment of a spinning disk-spindle system. The proposed method utilizes only the right eigenvectors of the eigenvalue problem to transform the large asymmetric finite element equations of motion into a small number of coupled equations, guaranteeing the accuracy of their numerical integration. The results are then back-substituted into the equations of motion to determine the forced response. The effectiveness of the proposed method was verified by comparing it with the responses from the classical methods of mode superposition with the general eigenvalue problems, and mode superposition with modal approximation. The proposed method was shown to be effective in determining the forced response represented by the asymmetric finite element equations of motion of a spinning flexible disk-spindle system supported by FDBs.

• 대한설비공학회지:설비저널
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• 제14권3호
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• pp.187-199
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• 1985

The low-temperatured radiant heating System like a panel heating system is recognized as nice means to make comfortable indoor environment. Perhaps, 'Ondol' would be a typical example of the Panel heating system. Nevertheless. Occupants in a radiantly heated Space which has an asymmetric radiant field may feel thermally discomfort due to the asymmetric radiation. The aim of this Study is to suggest the fundamental technical data for establishing Standards of thermally comfortable environment when designing a radiant heating System. Thermal distribution of indoor environment and the skin temperature of the occupants were measured at experimental room in KIER (Korea Institute of Energy and Resources). Whole/Regional thermal and comfort Sensation votes of the occupants were taken simultaneously in order to investigate the relationships between thermal environmental factor and the occupants' responses. The effect of an asymmetric radiation on thermal environment and the occupants' responses was analyzed by using a v.r.t.(vector radiant temperature). By this means, the thermally neutral limits for the ambient air temperature and the floor surface temperature by the occupants' responses were Obtained. And the recommended temperature limits of the indoor surface were derived from the experimental work and the theory of radiant and will provide thermal neutrality for man without any discomfort on the part of the body.

• Journal of the Korean Data Analysis Society
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• 제20권6호
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• pp.3015-3024
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• 2018

본 연구에서는 2000년 이후의 최근에 들어서 아시아의 대표적 주식시장에서 주식수익률 변동성이 정보의 호 악재에 따라 비대칭적으로 반응하는지의 여부를 실증적으로 분석하였다. 분석대상인 5개국의 아시아 주식시장 모두 주식시장에 호재가 도착할 경우 전기의 예기치 못한 양의 수익률의 제곱이 당기의 변동성에 미치는 영향에 비해, 전기의 예기치 못한 음의 수익률의 제곱이 당기의 변동성에 미치는 영향이 훨씬 더 크다는 분석결과를 보여주었다. 아시아 주요 5개 주식시장의 비대칭성의 상대적 크기를 비교해보면, 대만, 일본, 한국의 주식시장 순으로 더 크다는 결과를 보여주고 있으며, 상대적으로 말레이시아 주식시장은 비대칭성의 정도가 적은 분석결과를 보였다. 글로벌 금융위기 금융위기의 전과 후의 분석결과는 전구간의 분석결과와 동일하게 아시아 주식시장 주식수익률 변동성의 비대칭적 반응에서 모두 유의적인 양의 값을 가진다. 이는 최근 아시아 주요 주식시장에서 주식시장에 도착하는 정보가 주식수익률 변동성에 미치는 반응은 비대칭적이며, 또한 주식수익률 변동성을 예측할 때, 주식시장의 정보의 호재 및 악재 여부를 구분해야 한다는 것이다.

• 한국통신학회논문지
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• 제27권6A호
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• pp.533-539
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• 2002

터보부호는 반복복호 수와 인터리버 크기가 증가할수록 AWGN 채널환경에서 BER 성능이 향상된다는 것은 잘 알려진 사실이다. 그러나 반복복호 수와 인터리버 크기가 증가하면 상대적으로 복호 과정에서 복호지연과 계산량이 증가하게 된다. 또한 임의의 SM에서는 더 이상 BER 성능의 향상이 없는 flattening effect 현상이 발생하기 때문에 오류정정 능력의 한계에 도달하는 큰 단점을 가진다. 따라서 본 논문에서는 터보부호의 flattening effect 현상을 개선시키기 위해서 두 구성부호기의 구속장 뿐만아니라 생성다항식 자체도 서로 다르게 구성한 새로운 비대칭 구조를 갖는 터보부호를 제안한다. 제안된 비대칭 터보부호는 각각의 구성부호기의 생성다항식을 원시다항식과 소수다항식을 혼합한 형태로 구성하였고 구속장도 서로 다르게 구성하여 다양한 구조와 다양한 유효자유거리(effective free distance)를 갖도록 구성하였다. 제안된 비대칭 터보부호는 부호율이 1/3일 때 log-MAP 복호방법을 이용하여 상대적으로 작은 프레임(128. 256)과 큰 프레임(512, 1024)으로 인터리버 크기를 조절하면서 그 성능을 분석하였다. 모의실험 결과, 기존의 터보부호에 비해서 $10^{-4}$의 BER 영역에서 작은 프레임의 경우에 1.7dB~2.5dB이상의 우수한 성능을 나타냈으며 큰 프레임의 경우에 2.0dB~2.5dB 이상의 우수한 성능을 나타냄을 확인할 수 있었고 flattening effect 현상의 개선효과가 있음을 확인할 수 있었다.

• 한국운동역학회지
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• 제21권3호
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• pp.309-315
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• 2011

The purpose of this study was to evaluate the effect of asymmetric muscle force in lower extremity on dynamic balance during walking. Sixteen elementary students(age: 12.3${\pm}$0.7 yrs, height: 149.4${\pm}$9.7 cm, weight 40.6${\pm}$7.8 kg) who have no musculoskeletal disorder were recruited as the subjects. Temporal parameters, M-L inclination angle of XCoM-CoP, M-L and A-P CoP, loading rate, and decay rate were determined for each trial. For each dependent variable, a independent-sample t-test was performed to test if significant difference existed between each conditions(p<.05). The displacement of antero-posterior COP during RTO-LHC1 in SG was siginificantly smaller than corresponding value in AG. In contrast, the displacement of medio-lateral COP during RTO-LHC1 in SG was greater than those of AG. It seems that imbalance of muscle force may result in increasing the medio-lateral stance in order to minimize the instability. We found that the asymmetric muscle force in the lower extremity may be a reason for the awkward control of impact force.

• 생명과학회지
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• 제13권6호
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• pp.794-798
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• 2003

라세믹 phenyl oxirane 기질에 대한 asymmetric biohydrolysis 활성이 우수한 Rhodosporidium toruloides SJ-4를 생촉매로 이용하여 입체선택적 가수분해 반응을 통해 라세믹 phenyl oxirane 기질로부터 광학활성 (S)-phenyl oxirane를 회분식으로 생산하는 실험을 수행하였다. (R)-phenyl oxirane 이성질체에 대한 초기 가수분해 속도에 영향을 주는 실험인자들인 pH, 반응온도, DMSO cosolvent 첨가량 등에 대해 중심합성계획법을 이용한 반응표면 분석을 통해 가수분해반응 속도를 향상시킬 수 있는 최적 반응조건을 결정하였다. pH 7.4, 반응온도 34℃ 및 DMSO 첨가량 2.3%(v/v)의 조건에서 라세믹 기질 초기 농도 100mM로부터 약 10시간 정도의 반응을 통해 ee 값이 100%인 광학적으로 순수한 (S)-phenyl oxirane를 24% 정도 (이론수율 = 50%)의 높은 수율로 얻을 수 있었다. ^u Batch production of (S)-phenyl oxirane was investigated using epoxide hydrolase activity of Rhodosporidium toruloides SJ-4. Effect of reaction condition of asymmetric biohydrolysis of racemic phenyl oxirane was analyzed and optimized by response surface methodology. The optimal conditions of pH, temperature and DMSO cosolvent ratio were 7.4, 34 ℃, and 2.3%(v/v), respectively. The final yield was enhanced up to 67%, and reaction times required to reach 99% ee (enatiomeric excess) decreased down to 50% by response surface methodology Enantiopure (S)-phenyl oxirane with 100% enantiopurity and 24% yield (theoretical yield = 50%) was obtained from racemic substrate.