• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.363-366
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• 2004

PZT thin films were formed by rf-magnetron sputtering on $Pt/Ti/SiO_2/Si$ substrate. Bulk PZT target containing $5\%$ excess PbO was used. They were formed with in-situ process at $650^{\circ}C$ as total thickness of 175 and 250 nm after the depositing of thin PZT films at room temperature, i. e. 2-step Sputtering. It was found that the ferroelectric perovskite phase is formed at $650^{\circ}C$ by XRD and the interface between room temp.-layer and $650^{\circ}C$ -layer is not existent. In the samples undergoing 2-step sputtering the dielectric constant was 600 or more and the leakage current density was $2{\times}10^{-7}A/cm^2$. So, we found that the room temp.-layer on the bottom electrode stabilize the underlaid layers.

• 열처리공학회지
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• 제17권6호
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• pp.336-341
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• 2004

The effect of shot peening conditions on the fatigue properties of heat-treated spring steel has been investigated by using residual stress measurement and metallography. The mechanical properties of material did not change so much by shot peening. However, the fatigue strength and fatigue life increased about 20% to 40% by 1-step and 2-step shot peening process. The fatigue strength and life were closely related to the value and position of maximum compressive residual stress by shot peening process. In the case of warm shot peening, compressive residual stress of specimens shot peening processed at $200^{\circ}C$ was higher than those of specimens shot peening processed at room temperature, $100^{\circ}C$ and $300^{\circ}C$.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.305-310
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• 1997

국내에 신규로 건설되는 원자력발전소(이하 원전)는 부분강 제어봉을 설치하여 축방향의 출력 분포 제어에 별다른 어려움 없이 운전을 하고 있으나, 일부 가압 경수로형 원전의 경우는 부분강 제어봉이 설치되어 있지 않아 원자로 출력 변동시 출력분포 제어에 어려움이 많다. 기존 원전 경우의 제어봉 운전 방식은 원자로 출력의 균일한 제어를 위해 각 제어봉 뱅크를 순서적으로 운전하고 있으며, 각 뱅크간에는 일정한 수(일반적으로 113 Step) 만큼 중첩하여 운전하고 있다. 출력운전중에는 모든 제어봉을 인출하여 균일한 출력분포를 유지하며 축방향의 출력분포 제어를 위해 제어봉을 조절한다. 출력을 변동하면 제어봉이 원자로내에 삽입하게 되는 데, 먼저 D Bank가 삽입되며 D Bank가 113 Step에 도달하면 C Bank가 삽입되기 시작하는 데, D 130에서부터 C Bank가 삽입되어 제어값을 갖는 D 100 Step 까지는 축방향 출력 제어가 되지 않아 출력 편차가 제한값을 벗어나 출력을 급격히 감소해야 하는 등의 어려움이 있다. 본 연구는 제어봉의 중첩을 조절하여 C Bank를 조기에 노심에 삽입시의 영향을 분석하기 위하여 제어봉값이 출력에 미치는 영향을 예측하고, 제어봉 중첩수를 변경시에 노심에 미치게 될 안전성을 검토하였으며, 그 결과 중첩수를 조절할 경우 축방향 출력 분포를 초기부터 양호하게 제어할 것으로 예측된다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권6호
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• pp.841-846
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• 2014

The present study was conducted to determine whether the two-step time-restricted feeding improves the fattening traits of one-step time-restricted feeding in geese. Thirty-six 8-wk-old geese were allotted into one of three groups. Group R1 (the 1-step restricted feeding group) was allowed access to feed for 2 h in the morning from 8 wk to 14 wk of age. Group R2 (the 2-step restricted feeding group) was treated as Group R1, but was additionally fed for 2 h in the afternoon from 12 wk to 14 wk of age. Group C (the control group) was fed ad libitum from 8 wk to 14 wk of age. Feed intake and body weight (BW) were recorded daily and weekly, respectively. At 14 wk of age, the blood samples were collected to determine the fasting plasma levels of glucose, triacylglycerols and uric acid before sacrifice. The results showed that daily feed intake (DFI) was lower, feed efficiency (FE) was higher in both Groups R1 and R2 than in Group C, and daily gain (DG) in Group R2 was higher than in Group R1 during the whole experimental period (p<0.05). Group R1 exhibited lower abdominal and visceral fat weights in carcass than did Group C (p<0.05), and Group R2 was in intermediate. The fasting plasma glucose levels in Group C were higher, and triacylglycerol levels in Group R1 were higher, compared with the other groups (p<0.05). It is concluded that time-restricted feeding in the fattening period not only increases FE but reduces DFI, and the additional meal during the late fattening period improves the DG without the expense of FE in geese.

• 한국화재소방학회논문지
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• 제30권1호
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• pp.31-36
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• 2016

본 연구는 에폭시 계열 내화 도료의 열분해 특성을 파악하기 위해 열중량분석과 수치해석을 동시에 수행하였다. 에폭시 계열 내화 도료의 질량 감소 양상을 수치적으로 구현하기 위한 계산 모델이 소개되었으며, 계산 모델은 내화 도료의 여러 열분해과정을 단순화하여 4 단계의 순차적인 열분해 형태로 만들었다. 반응 속도는 Arrhenious 형태로 모델 되었고, 열중량분석을 통해 획득된 열분해 현상을 수치적으로 모사하기 위하여 화학 반응 매개변수들이 최적화되었다. 실험 결과 두 단계(two-step)와 세 단계(three-step)의 급격한 질량 감소가 질소와 공기 분위기에서 각각 나타났다. 또한 도료가 공기 분위기에 노출되었을 때 산소의 참여로 발생하는 복합적인 화학 반응들이 내화도료의 안정화를 도와 $200{\sim}500^{\circ}C$ 범위에서 질량 감소율을 낮추었다. 수치해석 결과는 실험과 비교하여 전체적으로 잘 일치하였으며 수치 모델에 포함되지 않은 $800^{\circ}C$ 이후를 제외하면 3% 미만의 오차를 보였다.

• 한국정보전자통신기술학회논문지
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• 제16권5호
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• pp.223-229
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• 2023

본 논문에서는 벡터제어 기법을 적용하는 교류 전동기 PI(비례-적분) 전류제어를 위한 주요 시스템 파라미터를 측정하는 방법을 제시한다. 전류제어를 위해서 PI 제어입력은 여러 선택적 방법에 의해 튜닝될 수 있다. 그 여러 방법들 중에서 주요 계통 파라미터인 권선 저항과 인덕턴스를 이용하는 방법이 빈번히 사용된다. 본 연구에서는 단순 궤환 제어의 결과들을 통해서 이 두 파라미터를 분석, 계측하는 기법을 제시한다. 이 분석적 측정 방법은 단위 계단 또는 다중 계단 기준 명령에 대해 단순 비례 궤환 이득을 이용하는 P 제어의 출력들을 분석하여 단계적으로 파라미터들을 계측해 내는 방법이다. 이 기법은 실시간적인 해석적 계측 방법으로 추가 계측 회로들 및 복잡한 계측 알고리즘들을 사용하지 않고 교류전동기의 벡터제어를 위한 토크성분과 자속성분 전류 제어이득을 같이 연산할 수 있는 방법이다.

• 한국미생물·생명공학회지
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• 제24권6호
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• pp.647-651
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• 1996

The development of an enrichment method for the rapid and effective identification of Salmonella spp. in sewage or food was studied. As a growth factor for Salmonella, 10 mM cyclic adenosine monophosphate (cAMP) in trypticase soy broth with 0.6% yeast extract (TSBYE) increased cell number five-folds and 0.6% yeast extract in selenite broth increased cell number ten-folds of control. Bile salts in selenite broth was tested for the selection of S. enteritidis in a mixture with Staphylococcus aureus, Pseudomonas aeruginosa, Lactobacillus plantarum and Escherichia coli. The latter four strains were effectively inhibited at 0.1% bile salt. A two-step culture method was used to enrich Salmonella spp.; a primary-enrichment and secondary- enrichment culture. At a primary-enrichment step, selenite broth with 0.6% yeast extract and 10 mM cAMP was used, and at a secondary-enrichment step, 0.1% bile salt was additionally used. Culture times of a primary- enrichment and a secondary-enrichment step were 8 hr and 6 hr, respectively. In this procedure, cell number increased from 10$^{0.3}$ to 10$^{8.5}$ with inhibition of other strains within 14 hr. In the case of an initial cell concentrarion as low as 10$^{-2}$ cfu/ml, a cell number increased to 10$^{7}$ cfu/ml by using a 10 hr primary-enrichment and 6 hr secondary-enrichment procedure.

• 한국표면공학회지
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• 제43권2호
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• pp.47-50
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• 2010

This work discusses a two-step electroless plating method for preparing a Pt thin film on p-type InGaAs substrate, which is defined as Pt I and Pt II. A thin Pt catalytic layer formed in Pt I bath on the substrate at $65^{\circ}C$. In the following Pt II bath, thick Pt films then easily grew on the sensitized layer on InGaAs previously formed in the Pt I bath. The growth of Pt film is strongly influenced by the plating temperature and pH value. To study the plating time effect, the plating of Pt II bath is 5 to 40 min at $80^{\circ}C$ after using Pt I bath at 50~$65^{\circ}C$ for 5min of pH 8~13. Pt film for ohmic contact to p-type InGaAs was successfully prepared by using the two-step Pt electroless plating.

• Progress in Superconductivity
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• 제3권1호
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• pp.60-64
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• 2001

We have studied properties of step-edge Junction prepared with crystal orientation of sapphire substrate. The Step on sapphire substrates fabricated by conventional photolithography method and Ar ion milling method. $CeO_2$ buffer layer and in-situ YBCO thin film were deposited on the stepped sapphire substrates by a pulsed laser deposition method with the predetermined optimized condition. The step angle was centre fled low angle of about $25^{\circ}$. The YBCO film thickness was varied to obtain various thickness ratios of the film to the step height in a range from 0.7 to 1.2. I-V curves of junction were showed RSJ-behavior, double junction structure, and hysteresis due to the crystal orientation of substrate.

• 환경생물
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• 제23권3호
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• pp.215-220
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• 2005

Through multiple stage analysis, the biochores in Korea were classified and organized as a hierarchy system. In the 1st step, the isopleth lines of warmth index $100^{\circ}C,\;85^{\circ}C,\;55^{\circ}C\;\cdot$ month and the coldness index $-8^{\circ}C,\;or-10^{\circ}C\;\cdot$ month, which indicate the boundaries of plant formation zones (Yim and Kira 1975; Yim 1977), were applied in the determination of major biochores. In the 2nd step, these biochores were subdivided into the five classes based on Thornthwaite's moisture index (Im) and Yim and Kira (1976), as follows: $100{\le}Im,100 In the 3 rd step, the analysis of topographic features yielded three categories of flatlands, gentle slope, and steep slope areas. These were obtained by adopting the $100{\times}100-meter$ gridded DEM and by considering the physical features of the Korean Peninsula. The features of relief in mountainous areas, waters, islands, etc. were converted into climatic indices. This grouping of biochores serves as a useful tool for the interpretation of the distributional patterns of vegetation of vascular plants and similar phenomena.