• Journal of Dairy Science and Biotechnology
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• 제18권1호
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• pp.1-8
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• 2000

본 실험은 산양유 casein의 조성 및 분별 그리고 이화학적 성질에 관하여 연구하고자 산양유의 일반성분을 분석하고 초유와 정상유로 산 casein을 제조하였으며 chymosin 작용과 전기영동에 의한 분리특성 및 DEAE-cellulose column chromatography에 의한 분별을 실시하였다. 그 결과, 산양 정상유의 단백질, 지방, 유당 함량은 각각 2.70${\pm}$0.27%, 3.82${\pm}$0.51% 및 4.10${\pm}$0.29%이었으며 정상유 casein보다 초유 casein에서chymosin처리에 의해 더 많은 NPN 함량이 유리되었다. 우유 및 산양유 casein을 chymosin 처리하여 전기영동을 실시한 결과 casein 조성이 서로 다르게 나타났으며 그 분리양상 또한 차이를 보였다. 산양 정상유 casein을 0.03${\sim}$0.25 M NaCl linear gradient로 DEAE-cellulose column chromatography를 실시한 결과 명확히 분별되지 않아 농도 기울기를 달리한 0.08${\sim}$0.18 M NaCl linear gradient로 column chromatography를 실시한 결과 5개의 Peak로 분리되었고 그 비율은 각각 5.27%, 26.07%, 25.97%, 30.40%및 12.29%이었다. 또한, 순수한 동정, 특히 n-casein 분획을 확인하기 위하여 chymosin을 처리한 산양 정상유 casein을 동일한 조건에서column chromatography를 실시한 결과 6개의peak로 분리되었으며 그 비율은 각각 17.06%, 9.10%, 17.85%, 20.11%, 27.03% 및 8.85%로 나타났다.

• 전자공학회논문지A
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• 제30A권10호
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• pp.20-26
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• 1993

The base-collector capacitance of an npn bipolar transistor in bipolar or BiCMOS technology has significant influence on the switching performances, and comprises pnjunction component and MOS component. Both components have complicated dependences on the isolation oxide structure, epitaxial doping density, and bias voltage. Analytical/empirical formulas for both components are derived in this paper for a generic isolation structure as a function of epitaxial doping density and bias voltage based on some theoretical understanding and two-dimensional device simulations. These formulas are useful in estimating the effect of device isoation schemes on the switching speed of bipolar transistors.

• 전자공학회논문지A
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• 제32A권10호
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• pp.25-34
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• 1995

A new vertical power MOSFET with over-current protection capability is proposed. The MOSFET consists of main power MOSFET cell, sensing MOSFET cell and lateral npn bipolar transistor. The proposed MOSFET may be fabricated by a conventional DMOS process without any additional fabrication step. Overcurrent state is sensed by the newly designed lateral bipolar transistor. Mixed-mode simulations proved that the overcurrent protection is achieved by the proposed MOSFET successfully with a small protection area less than 0.2 % of the total die area.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.967-970
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• 1999

A novel linear transconductor for low-voltage low-power signal processing is proposed. The transconductor consists of a pnp differential-pair and a npn differential-pair which are biased by local negative feedback. The simulation results show that the transcondcutor with transconductance of 50 $mutextrm{s}$ has a linearity error of 0.05% and the power dissipation is 2.44 ㎽ over an input linear range from -2V to +2V at supply voltage $\pm$3V.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.941-944
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• 2000

This paper proposes, for the first time, the design of class I pull-push power amplifier. With the new design, the output power is increased by four times when compared to conventional single-end class I connection amplifier with the same supply voltage. The performance of the proposed amplifier is verified by with a 100-kHz power amplifier constructed using general-purpose NPN transistors.

• 전자공학회논문지A
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• 제30A권3호
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• pp.88-94
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• 1993

In this paper, a simple Ebers-Moll Model for the heterojunction bipolar transistor is presented. Using the model structure for the npn type HBT, the current-voltage characteristics was analyzed. And from the obtained terminal currents, the Ebers-Moll equations were derived. Then substituting the physical parameters for heterojunction to those for homojunction, this model would be used to analyze the characteristics of single and/or duble heterojunction HBT's. And directly relating model parameters to device parameters, it would be also used to optimize the characteristics of HBT's. The simulated results using this model were in good agreement with experimental data.

• Asian-Australasian Journal of Animal Sciences
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• 제17권10호
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• pp.1400-1410
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• 2004

Eight crossbred (75% Holstein Friesian) cows in mid-lactation were randomly assigned to a switchback design with a 2x2 factorial arrangement to evaluate two nonstructural carbohydrate (NSC) sources (corn meal and cassava chips) with different rumen degradability and used at two levels of NSC (55 vs. 75%) with protein source (supplied by urea in the concentrate mix). The treatments were 1) Low degradable low level of corn (55%) 2) Low degradable high level of corn (75%) 3) High degradable low level of cassava (55%) and 4) High degradable high level of cassava (75%). The cows were offered the treatment concentrate at a ratio to milk yield at 1:2. Urea-treated rice straw was offered ad libitum as the roughage and supplement with 1 kg/hd/d cassava hay. The results revealed that total DM intake, BW and digestion coefficients of DM were not affected by either level or source of energy. Rumen fermentation parameters; NH3-N, blood urea nitrogen and milk urea nitrogen were unaffected by source of energy, but were dramatically increased by level of NSC. Rumen microorganism populations were not affected (p>0.05) by source of energy, but fungal zoospores were greater for cassava-based concentrate than corn-based concentrate. Milk production and milk composition were not affected significantly by diets containing either source or level of NSC, however concentrate than corn-based concentrate averaging (4.4 and 4.2, respectively). Likewise, income over feed, as estimated from 3.5% FCM, was higher on cassava-based concentrate than corn-based concentrate averaging (54.0 and 51.4 US$/mo, respectively). These results indicate that feeding diets containing either cassava-based diets and/or a higher of oncentrates up to 75% of DM with NPN (supplied by urea up to 4.5% of DM) can be used in dairy rations without altering rumen ecology or animal performance compared with corn-based concentrate.

• 한국인터넷방송통신학회논문지
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• 제15권1호
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• pp.253-259
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• 2015

우리는 이 논문에서 교류전압원의 극성에 따라서 쌍방향으로 동작하는 반도체 변압기설계를 제시한다. 변압기는 회로 사이의 유도성 결합에 의하여 에너지를 전달하는 장치이다. 대부분의 변압기는 교류 전압에 의하여 1차 및 2차 코일로 구성된 장치이다. 우리가 제시하는 시스템은 전압신호 레벨을 두 방향으로 즉, 전원에서 부하까지 전압신호가 전달되기도 하고, 부하에서 전압원까지 전달되기도 한다. 전환하는 하나의 회로로 설계되어있다. 구성한 반도체 스위치는 NPN 트랜지스터가 교류 전압원 단자에 연결되어 있고, 에너지 저장 요소로서는 이미터 단자에 연결되어 있는 인덕터를 채택하였다. 제어 신호는 반도체의 베이스 단자에 인가된다. 제시하는 시스템은 전압신호의 진폭을 가역 방향으로 변화시킬 수 있다.

• 대한전자공학회논문지SD
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• 제38권11호
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• pp.828-835
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• 2001

고정도 전류-모드 신호 처리를 위한 새로운 바이폴라 트랜스레지스턴스 증폭기(TRA)와 이것의 오프셋 보상된 TRA를 제안하였다. 두 TRA는 전류 입력을 위한 두 개의 전류 폴로워, 전류차를 얻기 위한 전류 가산기, 전류를 전압으로 변환시키기 위한 저항, 그리고 전압 출력을 위한 전압 폴로워로 구성되었다. 오프셋 보상된 TRA는 TRA의 오프셋 전압을 감소시키기 위한 다이오드 결선된 npn과 pnp 트랜지스터를 채용하였다. 시뮬레이션 결과, TRA근 입-출력 단자에서 0.5 Ω의 임피던스와 40 mV의 오프셋 전압을 갖고 있다는 것이 확인되었다. 오프셋 보상된 TRA는 1.1 mV의 오프셋 전압과 0.25 Ω의 임피던스를 갖고 있다. 두 개의 TRA를 단위-이득의 트랜스레지스턴스를 갖는 전류-전압 변환기로 이용할 때 3-dB 차단 주파수는 40 MHz이다. 제안한 두 TRA의 전력 소비는 11.25 mW이다.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.795-802
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• 2014

The aim of this study was to determine the effects of temperature and supplementation with skim milk powder (SMP) on the microbial and proteolytic properties during the storage of cottage cheese. Cottage cheese was manufactured using skim milk with 2% SMP and without SMP as the control, and then stored at $5^{\circ}C$ or $12^{\circ}C$ during 28 days. The chemical composition of the cottage cheese and the survival of the cheese microbiota containing starter lactic acid bacteria (SLAB) and non-starter culture lactic acid bacteria (NSLAB) were evaluated. In addition, changes in the concentration of lactose and lactic acid were analyzed, and proteolysis was evaluated through the measurement of acid soluble nitrogen (ASN) and non-protein nitrogen (NPN), as well as electrophoresis profile analysis. The counts of SLAB and NSLAB increased through the addition of SMP and with a higher storage temperature ($12^{\circ}C$), which coincided with the results of the lactose decrease and lactic acid production. Collaborating with these microbial changes, of the end of storage for 28 days, the level of ASN in samples at $12^{\circ}C$ was higher than those at $5^{\circ}C$. The NPN content was also progressively increased in all samples stored at $12^{\circ}C$. Taken together, the rate of SLAB and NSLAB proliferation during storage at $12^{\circ}C$ was higher than at $5^{\circ}C$, and consequently it led to increased proteolysis in the cottage cheese during storage. However, it was relatively less affected by SMP fortification. These findings indicated that the storage temperature is the important factor for the quality of commercial cottage cheese.