• 한국해양공학회지
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• 제1권2호
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• pp.93-100
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• 1987

Corrosion fatigue cracking of the austenitic stainless steel(bese metal & heat affected zone by TIG weld) was studied experimentally under the environments of various specific resistance and air. The characteristics of corrosion fatigue crack growth rate and the environmental constants of paris' rule were investigated for SUS 304 weldments in the various specific resistance. The influences of stress intensity factor range and corrosion on the crack growth rate were compared. The characteristics of corrosion fatigue cracking for the weldments were inspected from mechanical, electrochemical and microstructural point of view. Main results obtained are as follows: 1) As the specific resistance decreases, the environmental constant C of paris'rule increases(hence the corrosion fatigue crack growth rate is rapid), but the environmental constant m decreases, so the effect of corrosion to the crack growth rate is more susceptible than thet of stress intensity factor range. 2) As the stress intensity factor range decreases, the corrosion fatigue crack growth rate of heat affected zone is more susceptible than that of the base metal. 3) The corrosion fatigue crack growth rate of the heat affected zone is more rapid than that of the base metal, because of the phenomenon of softening and the less noble potential coused by wedlding heat cycle. 4) The corrosion fatigue cracking of SUS 304 weldment appears transgranular fracture.

• 전자공학회논문지S
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• 제34S권10호
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• pp.1-8
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• 1997

In this paper, we propose a call admission control scheme which can be used in real environment for the traffic cibtrik if a base station if DS-CDNA cellular systems. The proposed scheme estimates the mean and variance of other cell interference by using the values used for the closed loop power control. The reerse link capacity of the base station can be calculated by using the estimated mean and variance of other cell interference. The base station admits a call only if the number of users is less than the calculated reverse link capacity. In addition, we propose a simple method to obtain the equivalent number of voice call users per one data call user in multi-rate traffic environment. The method can be applied to call admission control in multi-rate traffic environment.

• 한국환경과학회지
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• 제17권8호
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• pp.919-924
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• 2008

The surface properties and adsorption rates of activated carbon modified with acid and base were compared. The distribution ratio of C and C-H on the surface of activated carbon were decreased by modification with acid and base, but the distribution ratio of C-O, C=O, and O=C-O were increased. Base modification damaged the surface of activated carbon more than acid modification, it caused the effect of 6 percent increments of surface area. Adsorption rate model was more suitable to second order equation than first order equation. Adsorption rate was controlled by adsorption in pore better than in surface.

• 한국체육학회지인문사회과학편
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• 제55권6호
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• pp.361-373
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• 2016

프로야구에서 팀 승률은 관중유지에 직결되기 때문에 가장 중요한 지표라 할 수 있다. James(1980)가 제안한 피타고라스 지수에 의거한 승률 도출은 실제 승률과 거의 일치하기 때문에 팀 전략을 수립하는 데 도움을 줄 수 있는 방법으로 알려져 있다. 이에 본 연구에서는 2005년부터 2014년까지 10년 간 실제승률과 피타고라스 지수에 의거한 승률을 토대로 어떠한 세부기록이 이격도를 양산해내는지를 알아보고자 했고, 이를 토대로 한국프로야구 구단의 성과 향상 방안을 도출 하는 데 본 연구의 목적이 있다. 연구결과, 10년간 기대승률 대비 실제 승률은 +.062에서 -.054로 확인되었고, 이러한 결과가 도출되는 과정에서 피볼넷, 피삼진, 볼넷, 타율, 희생플라이 등의 기록이 프로야구단의 성과에 영향을 미치는 것으로 나타났다. 이에 구단은 타자로 하여금 선구안을 향상시키는 훈련을 통해 볼넷을 많이 얻어내고 삼진을 적게 당하는 전략을 구사해야 할 것이고, 투수의 경우 다른 요인보다 제구력 향상에 신경을 기울여 볼넷을 줄여나가야 할 것으로 나타났다.

• Journal of Korean Biological Nursing Science
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• 제19권2호
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• pp.76-85
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• 2017

Purpose: The purpose of this study was to compare the effects of $21^{\circ}C\;CO_2$ and $37^{\circ}C\;CO_2$ pneumoperitoneum on body temperature, blood pressure, heart rate, and acid-base balance. Methods: Data were collected at a 1300-bed university hospital in Incheon, from February through September 2012. A total of 74 patients who underwent laparoscopic colectomy under general anesthesia with desflurane were randomly allocated to either a control group or an experimental group. The control group received $21^{\circ}C\;CO_2$ pneumoperitoneum; the experimental group received $37^{\circ}C\;CO_2$ pneumoperitoneum. The pneumoperitoneum of the two groups was under abdominal pressure 15 mmHg. Body temperature, systolic blood pressure, heart rate and acid-base balance were assessed at 30 minutes and 90 minutes after pneumoperitoneum, and again at 30 minutes after arriving at the Post Anesthesia Care Unit. Results: Body temperature in the $37^{\circ}C\;CO_2$ pneumoperitoneum group was significantly higher (F= 9.43, p< .001) compared to the $21^{\circ}C\;CO_2$ group. However, there were no statistically significant differences in systolic blood pressure (p= .895), heart rate (p= .340), pH (p= .231), PaCO2 (p= .490) and HCO3- (p= .768) between the two groups. Conclusion: Pneumoperitoneum of $37^{\circ}C\;CO_2$ is effective for the increase of body temperature compared to pneumoperitonium of $21^{\circ}C\;CO_2$, and it does not result in a decrease of blood pressure, heart rate or acid-base imbalance.

• Korean Chemical Engineering Research
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• 제47권5호
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• pp.615-619
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• 2009

$Tr{\ddot{o}}ger$'s base 중 (+)-$Tr{\ddot{o}}ger$'s base는 항혈전제로 Thromboxane A2($T{\times}A2$) Synthase의 효소 활성을 저해하여 동맥경화의 치료제로 널리 사용되고 있다. 따라서 (+)-$Tr{\ddot{o}}ger$'s base를 라세미 혼합물로부터 순수하게 분리하는 것은 중요한 연구대상이다. 하지만 실험을 통한 (+)-$Tr{\ddot{o}}ger$'s base의 순수한 분리에는 많은 시간과 비용이 필요하게 되므로 분리 효율의 향상에 많은 어려움이 있다. 이러한 단점을 보완하고자 Aspen Chromatography 전산 모사는 여러 조건하에서 직접 실험을 하지 않는 효율적인 시뮬레이션 방법으로서 분리 효율 등을 예측할 수 있으므로 생산성 향상에 드는 시간과 비용을 절약할 수 있다. Aspen Chromatography simulator로 $Tr{\ddot{o}}ger$'s base의 주입량과 이동상 속도를 변화시켜 TB(-)와 TB(+)의 분리도, 수율 그리고 다양한 흡착식을 비교하였다. TB(-)와 TB(+)의 분리도와 순수한 수율은 이동상 속도 0.25 mL/min일 때 가장 높았다. 고정상과 이동상 농도사이의 관계식을 표시하는 등온흡착식을 변화하여 전산모사한 결과 Ideal Adsorbed Solution(IAS) Statistical Langmuir 등온흡착식이 분리 효율에 좋은 결과를 가져왔다.

• 한국컴퓨터정보학회논문지
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• 제15권1호
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• pp.207-217
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• 2010

미국의 서브프라임 모기지 사태로 세계 주식시장의 폭락을 가져왔다. 개인 투자자는 외국인과 기관에 비해 손실률이 더 큰 것으로 판단되었다. 따라서 인터넷 HTS를 이용한 주식투자에 있어서 좀 더 과학적이고 기계적인 투자가 필요하다. 본 논문은 하락기 하락조정기 상승기 상승조정기에 개인 기관 외국인 Knowledge Base HTS를 이용한 주식 수익률 분석이다. Knowledge Base HTS인 e-friend를 설치한다. HTS 툴인 추세선, MACD, Bollinger Bands, Stochastic slow의 기능을 이용하여 HTS가 실제 주식 거래에서의 종합주가지수와 기관의 펀드수익률, 외국인 수익률을 비교분석 한다. 일반적으로 5개 종목을 거래한다는 가정 하에 하락기, 하락조정기, 상승기, 상승조정기에 있어서 소형주 5개, 중형주 5개, 대형주 5개의 수익률을 비교함으로서, 실제적인 하락률과 상승률에 관한 수익(손실)율을 비교 연구하여 금융 IT 분야 발전을 연구하는데 의의가 있다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.247-250
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• 2006

기존 연구를 통해 고체추진제 연소속도 측정을 위한 초음파 측정 시스템 및 연소속도 산정 기법을 개발하였으며, 개발 시스템을 적용하여 composite 추진제의 연소속도를 측정하였다. 본 연구에서는 연소 압력 증가에 따라 연소속도가 비선형적으로 변하는 double base형 고체 추진제 인 N-5와 AA-2 고체추진제의 연소속도를 개발 시스템을 이용하여 측정하였으며, 스트랜드버너법으로 측정된 값과의 비교를 통해 측정결과의 신뢰성을 평가하였다.

• Journal of Welding and Joining
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• 제23권2호
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• pp.52-58
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• 2005

This study was carried out to investigate the effect of bonding temperature and heating rate on transient liquid phase diffusion bonding of Ni-base superalloy. The heating rate was varied by $0.1^{\circ}C$/sec, $1^{\circ}C$/sec, $10^{\circ}C$/sec to the bonding temperatures $1100^{\circ}C,\;1150^{\circ}C,\;1200^{\circ}C$ under vacuum. As bonding temperature increased, maximum dissolution width of base metal increased, but a dissolution finishing time decreased. The eutectic width of insert metal in the bonded interlayer decreased linearly in proportion to the square root of holding time during isothermal solidification stage. The bonding temperature was raised, isothermal solidification rate slightly increased. As the heating rate decreased and the bonding temperature increased, the completion time of dissolution after reaching bonding temperature decreased. When the heating rate was very slow, the solidification proceeded before reaching bonding temperature and the time required for the completion of isothermal solidification became reduced.

• 한국도로학회논문집
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• 제19권6호
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• pp.37-46
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• 2017

PURPOSES : A composite pavement utilizes both an asphalt surface and a concrete base. Typically, a concrete base layer provides structural capacity, while an asphalt surface layer provides smoothness and riding quality. This pavement type can be used in conjunction with rollercompacted concrete (RCC) pavement as a base layer due to its fast construction, economic efficiency, and structural performance. However, the service life and functionality of composite pavement may be reduced due to interfacial bond failure. Therefore, adequate interfacial bonding between the asphalt surface and the concrete base is essential to achieving monolithic behavior. The purpose of this study is to investigate the bond characteristics at the interface between asphalt (HMA; hot-mixed asphalt) and the RCC base. METHODS : This study was performed to determine the optimal type and application rate of tack coat material for RCC-base composite pavement. In addition, the core size effect, temperature condition, and bonding failure shape were analyzed to investigate the bonding characteristics at the interface between the RCC base and HMA surface. To evaluate the bond strength, a pull-off test was performed using different diameters of specimens such as 50 mm and 100 mm. Tack coat materials such as RSC-4 and BD-Coat were applied in amounts of 0.3, 0.5, 0.7, 0.9, and $1.1l/m^2$ to determine the optimal application rate. In order to evaluate the bond strength characteristics with temperature changes, a pull-off test was carried out at -15, 0, 20, and $40^{\circ}C$. In addition, the bond failure shapes were analyzed using an image analysis program after the pull-off tests were completed. RESULTS : The test results indicated that the optimal application rate of RSC-4 and BD-Coat were $0.8l/m^2$, $0.9l/m^2$, respectively. The core size effect was determined to be negligible because the bond strengths were similar in specimens with diameters of 50 mm and 100 mm. The bond strengths of RSC-4 and BD-Coat were found to decrease significantly when the temperature increased. As a result of the bonding failure shape in low-temperature conditions such as -15, 0, and $20^{\circ}C$, it was found that most of the debonding occurred at the interface between the tack coat and RCC surface. On the other hand, the interface between the HMA and tack coat was weaker than that between the tack coat and RCC at a high temperature of $40^{\circ}C$. CONCLUSIONS : This study suggested an optimal application rate of tack coat materials to apply to RCC-base composite pavement. The bond strengths at high temperatures were significantly lower than the required bond (tensile) strength of 0.4 MPa. It was known that the temperature was a critical factor affecting the bond strength at the interface of the RCC-base composite pavement.