• Corrosion Science and Technology
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• 제12권5호
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• pp.209-214
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• 2013

In the industry, accelerated corrosion test is used for the life time prediction. When anti-corrosion test proceeds in real environments, it is difficult that we predict and evaluate the corrosion life time because of the long test time such as 10 years or more time. Accelerated corrosion test and Salt spray test are able to test corrosion life time of products in the laboratory instead of outdoor corrosion test. Experimental procedure is selected for the corrosion standard specimen, exposure of the specimens, measurements of the mass loss and evaluating the mass loss data. As a result, the acceleration factor of the accelerated corrosion test to the outdoor corrosion test is 414.8. Therefore we can predict the corrosion life time of carbon steel during a short time period.

• Journal of Yeungnam Medical Science
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• 제21권2호
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• pp.231-236
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• 2004

제 VII 혈액응고인자는 외인계 혈액응고기전에 매우 중요한 역할을 한다. 선천성 제 VII 혈액응고인자 결핍증은 구미에서는 인구 500,000명당 한명의 발생률을 보이는 드문 질환으로 상염색체 열성으로 유전되는 것으로 알려져 있으며 국내에서의 보고는 드물다. 이에 저자들은 경막하 출혈로 입원한 환자에서 발견된 선천성 제 VII 혈액응고인자 결핍증을 경험하고 보고하는 바이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.593-596
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• 2008

콘크리트의 블리딩은 재료분리의 일종으로서 콘크리트 품질뿐만 아니라 내구성을 저하시키는 원인으로 작용한다. 본 연구에서는 콘크리트 블리딩에 영향을 미칠 것으로 예상되는 시멘트 및 믹싱시간의 두 요인의 변화에 따른 특성을 파악하여 블리딩 제어기술 확보를 위한 기초자료를 제공하고자 한다.연구결과에 의하면, 믹싱시간이 증가할수록 블리딩율도 증가하는 추세를 나타내고 있었다. 블리딩양(믹싱시간 90초)은 시멘트 특성에 의한 차이가 뚜렷하게 나타나고 있었으며, 콘크리트 특성값(블리딩율, 슬럼프 및 재령 3일 압축강도)은 믹싱시간과 비례적인 관계가 있었다. 또한, 슬럼프 손실율과 믹싱시간은 반비례적인 관계가 존재하였고, 압축강도값은 초기재령에서만 믹싱시간에 의한 영향을받고 있었다.향후, 최적 믹싱시간 도출을 위한 다양한 검토가 필요할 것으로 판단된다.

• 대한간호학회지
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• 제29권1호
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• pp.61-71
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• 1999

Sleep is a necessity for survival. Disruption of sleep leads to numerous adverse physiological and psychological consequences. These could be particularly undesirable for older patients, who are subject to many additional factors. But there is limited research related to hospitalized elderly in Korea. The purpose of the study is to explore sleep patterns and disturbing factors of before and after hospitalization, in order to present basic information regarding elderly sleep to develop nursing intervention. The sample consisted of 32 elderly men and women between the ages of n and 87 years. Data collection was done from September to November 1997. Measures of sleep patterns and related factors were obtained from self-reported sleep questionnaires. Analysis of data was done by use of t-test, paired t-test, ANOVA, and Pearson Correlation Coefficient. The results of this study were summarized as follows : 1. In comparision between before and after admission of their sleep pattern, “sleep onset” tends to be delayed and nocturnal sleep time was significantly reduced. So, hospitalized elderly reported less total sleep time than before admission. 2. Regarding the sleep disturbing factors, medication(hypnotics ; 37.5%), physiological factor (snoring ; 59.4%) environmental factor (pillow ; 78.1%), emotional factor(anxiety related to disease ; 37.5%), and illness factor(fatigue ; 34.7%) were reported. 3. Significant differences in gender were found. Men had more disturbances in sleep than women owing to difficulty in falling a sleep and lack of nocturnal sleep. Women consumed more sleep inducing drugs. Significant increase was reported in napping during the day with increasing age. 4. Significant differences between good sleepers and poor sleepers were found for the following variables : nocturnal sleep time, total sleep time, bed time, sleep onset latency time, sleep latency time after nocturnal awakening, time spent in bed upon arousal, environmental factors, and emotional factors. In conclusion, it was found that the quantity and quality of sleep were significantly altered in hospitalized elderly, but adequate strategies for better sleep were not practiced. Further research is needed to develop Intervention strategies to promote sleep and to prevent sleep problems.

• Smart Structures and Systems
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• 제32권1호
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• pp.9-21
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• 2023

The parameters of civil engineering structures have time-variant characteristics during their service. When extremely large external excitations, such as earthquake excitation to buildings or overweight vehicles to bridges, apply to structures, sudden or gradual damage may be caused. It is crucially necessary to detect the occurrence time and severity of the damage. The unscented Kalman filter (UKF), as one efficient estimator, is usually used to conduct the recursive identification of parameters. However, the conventional UKF algorithm has a weak tracking ability for time-variant structural parameters. To improve the identification ability of time-variant parameters, an adaptive UKF with forgetting factor (AUKF-FF) algorithm, in which the state covariance, innovation covariance and cross covariance are updated simultaneously with the help of the forgetting factor, is proposed. To verify the effectiveness of the method, this paper conducted two case studies as follows: the identification of time-variant parameters of a simply supported bridge when the vehicle passing, and the model updating of a six-story concrete frame structure with field test during the Yangbi earthquake excitation in Yunnan Province, China. The comparison results of the numerical studies show that the proposed method is superior to the conventional UKF algorithm for the time-variant parameter identification in convergence speed, accuracy and adaptability to the sampling frequency. The field test studies demonstrate that the proposed method can provide suggestions for solving practical problems.

• Journal of Power Electronics
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• 제16권5호
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권3호
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• pp.39-46
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• 2014

Hydraulic conductivity is an important parameter, representing permeable property of the groundwater in aquifers, in the issues of groundwater development, groundwater contamination, and groundwater flow, etc. We estimated a relationship between hydraulic conductivity and electrical properties (formation factor, chargeability, and time constant) of silty sand in the laboratory. For this study, we conducted grain size analysis, constant head permeameter test, and measured electrical resistivity and spectral induced polarization of silty sand samples collected from the riverside alluvium of the Nakdong River in Nogok-ri area, Dasan-myeon, Goryeong-gun in Gyeongbook Province, Korea. In the laboratory test, we used soil samples of approximately uniform porosity with 0.5% error range, and kept the electrical resistivity of pore water with 100 ohm-m. As a result, the relationship between effective particle size and hydraulic conductivity agrees fairly well with the existing empirical formulas. Hydraulic conductivity was correlated with formation factor, chargeability, and time constant: hydraulic conductivity increased with increasing formation factor and time constant as well as with decreasing chargeability.

• 한국동물위생학회지
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• 제46권2호
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• pp.107-113
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• 2023

Tenebrio molitor, rich in protein, is used as an alternative protein source. Many studies have evaluated Tenebrio molitor larvae (TML) for anti-obesity effects, fatty liver relief, antithrombosis, and antioxidant effects. In this study, we prepared an experimental diet by adding Tenebrio molitor larvae oil (TMLO) to feed and administered it to adult male ICR mice for six weeks. The study assessed the weight gain of mice, prothrombin time (PT), activated partial thromboplastin time (aPTT), blood coagulation time, and the activities of coagulation factor VII and coagulation factor XII. The weight gain of mice was suppressed in the groups fed with TMLO, indicating a potential anti-obesity effect. The blood coagulation time was delayed in the TMLO-fed groups, as evidenced by amplified PT and aPTT values. Furthermore, the activities of coagulation factor VII and coagulation factor XII were diminished in the TMLO-treated groups, indicating a potential thrombosis relieving effect. The concentrations of thromboxane B2 and serotonin declined in the TMLO-fed groups, signifying potential blood circulation effects. Finally, blood triglyceride and LDL-cholesterol concentrations were reduced in the TMLO-fed groups. In summary, TMLO supplementation may have an inhibitory effect on liver damage and blood clot formation caused by obesity.

• 대한영양사협회학술지
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• 제7권2호
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• pp.144-152
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• 2001

This research reviews the characteristics of consumption oriented culture of post modern society and describes the food consumption culture based on the evaluative criteria pattern in eating in Ulsan Metropolitan City. The subjects consisted in 217 full-time housewives and 129 cooks. The evaluative criteria of eating scale with 4 components - the eating atmosphere factor, the preference factor, the quality factor and the table factor- is described and interpreted in the context of consumption oriented culture. 4 clusters were decided through cluster analysis; preference and quality pursuing type, high involvement type, consumerism culture pursuing type and low involvement type. Among socio-economic variables, the evaluative criteria pattern of eating was significantly associated with occupation. The results of factor analysis and cluster analysis proved that the full-time house wives and cooks in Ulsan Metropolitan city showed the propensity to consumption oriented culture in food consumption culture.

• Communications for Statistical Applications and Methods
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• 제15권6호
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• pp.825-835
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• 2008

계량경제학 분야에서 널리 쓰이는 MGARCH(multivariate GARCH)모형은 여러개의 시계열자료들의 변동성을 함께 모형화한다. 그러나 변수가 많아질수록 추정해야 할 모수의 수가 급격하게 늘어나는 문제점이 있다. 본 연구에서는 인자 모형을 통해 자료의 차원을 축소시킴로써 이러한 문제를 해결하고자 하였다. 국내의 주가수익률 자료에 통계적 인자 모형과 fundamental factor model을 적용하여 각각의 의미 있는 인자들을 얻은 후 이를 MGARCH모형에 적합시켰다. 또한 두 인자모형을 바탕으로 얻어진 최종 모형들의 MSE, MAD와 VaR(Value at Risk)를 계산하여 예측력을 비교하고자 한다.