• 한국산학기술학회논문지
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• 제21권8호
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• pp.557-562
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• 2020

코로나19로 인해서 비대면 강의환경에서 온라인 학습이 교육환경의 주요 학습기법으로 채택되고 있다. 온라인 학습패턴이 학업성적에 어떤 영향을 미치는지에 관한 연구가 부족하여, 본 연구에서는 학습자들의 온라인 동영상 학습횟수와 시간을 주요 요소로 두고, 매 학습에 대한 형성 평가와 함께 중간고사 기말고사를 바탕으로 학습효과의 상관관계를 분석하였다. 분석 대상은 대학에서 예체능 학부 학생들이 가장 어려워하는 교양 과목 중 컴퓨터 프로그래밍 교과목을 분석하였다. 실제 학생들의 사례를 분석한 결과 매주 실시한 형성 평가와 학습회수, 학습 시간과는 상관관계가 없는 것으로 나타났고, 중간고사와 기말고사와는 평소 학습회수(r=.39 p<0.05)와 학습 시간(r=.42 p<0.05)이 상관관계가 있는 것으로 나타났다. 강의 진행 과정에서 SMS 문자, 게시판, 메일 등의 요소는 모든 학생이 접하지 못하여 제외하였으므로, 앞으로는 좀 더 다양한 요인을 고려하여 비대면 강의환경에서의 학습자 패턴을 분석하고 연구한다면 학습자들의 요구와 학습효과를 향상할 수 있을 것이다.

• 한국건설관리학회논문집
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• 제9권1호
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• pp.66-76
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• 2008

플랜트공사는 토목, 건축, 기계, 전기 공종들이 연동되어 작업이 진행되는 복합공종이다. 또한 일반 공사와 비교시 매우 짧은 공기에 대규모의 공사를 수행하여야 하는 공정상의 특징을 갖고 있다. 이러한 특성들로 인하여 플랜트공사에서 공정관리는 매우 중요한 요소가 되고 있다. 4D CAD에 의한 공정정보의 시각화는 이러한 복합공정에서 더욱 필요성을 갖게 된다. 본 연구에서는 플랜트공사의 특성을 고려한 4D CAD시스템 기능 구성방법론과 실제 시스템 개발을 시도한다. 이를 위하여 플랜트공사 현장의 공정작업 특성을 분석한 후 4D CAD 기능을 구성함으로써, 기존 시스템에서 시도되지 않은 플랜트공사에 특화된 공정시각화 기능구축을 시도하고 있다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5681-5685
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• 2012

Three kinds of survival rates are generally used depending on the purpose of the investigation: overall, cause-specific, and relative. The differences among these 3 survival rates are derived from their respective formulas; however, reports based on actual cancer registry data are few because of incomplete information and short follow-up duration recorded on cancer registration. The aim of this study was to numerically and visually compare these 3 survival rates on the basis of data from the Nagasaki Prefecture Cancer Registry. Subjects were patients diagnosed with cancer and registered in the registry between 1999 and 2003. We calculated the proportion of cause of death and 5-year survival rates. For lung, liver, or advanced stage cancers, the proportions of cancer-related death were high and the differences in survival rates were small. For prostate or early stage cancers, the proportions of death from other causes were high and the differences in survival rates were large. We concluded that the differences among the 3 survival rates increased when the proportion of death from other causes increased.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.559-568
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• 2017

Harmonic/inter-harmonic detection and analysis is an important issue in power system signal processing. This paper proposes a fast algorithm based on matching pursuit (MP) sparse signal decomposition, which can be employed to extract the harmonic or inter-harmonic components of a distorted electric voltage/current signal. In the MP iterations, the method extracts harmonic/inter-harmonic components in order according to the spectrum peak. The Fast Fourier Transform (FFT) and nonlinear optimization techniques are used in the decomposition to realize fast and accurate estimation of the parameters. First, the frequency estimation value corresponding to the maxim spectrum peak in the present residual is obtained, and the phase corresponding to this frequency is searched in discrete sinusoids dictionary. Then the frequency and phase estimations are taken as initial values of the unknown parameters for Nelder-Mead to acquire the optimized parameters. Finally, the duration time of the disturbance is determined by comparing the inner products, and the amplitude is achieved according to the matching expression of the harmonic or inter-harmonic. Simulations and actual signal tests are performed to illustrate the effectiveness and feasibility of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2047-2049
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• 1997

Computers and automatic equipment are very sensitive to the disturbances such as voltage transients, voltage sag, and harmonics. These disturbances cause them to have a malfunction or fault which brings about damages and losses. UPS (uninterruptible power supply) and SPS(stand-by power supply) have been used to provide the required voltage in a critical load without disturbances. However, UPS has appreciable losses due to the operation of the inverter in full rated power at all times. SPS, although whose inverter losses are smaller than those of UPS, transfers disturbances with a short duration to the load, due to the limited reaction time. In this research, a dynamic voltage compensator, which can make up for the weakness of UPS and SPS, is proposed. The operation of the proposed system was verified by a computer simulation. A hardware scaled-model was fabricated and tested to conform the feasibility of the actual system development.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.459-464
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• 2007

Seismic control performance of MR dampers, which have severe nonlinearity, differs with respect to the dynamic characteristics of an earthquake such as magnitude, frequency and duration. In this study, the effects of excitation characteristics on the equivalent linear system of a building structure with the MR damper are investigated through numerical analysis for artificial ground motions generated from different response spectrums. The equivalent damping ratio of the structure with the MR damper is calculated using Newmark and Hall's equations for ground motion amplification factors. It is found that the equivalent damping ratio of the structure with the MR damper is dependent on the ratio of the maximum friction force of the MR damper over excitation magnitude. Frequency contents of the earthquake ground motion affects the equivalent damping ratio of long-period structures considerably. Also, additional damping effect caused by interaction between the viscousity and friction of the MR damper is observed. Finally, response reduction factors for equivalent linear systems are proposed in order to improve accuracy in the prediction of the actual nonlinear response.

• Journal of Plant Biotechnology
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• 제4권4호
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• pp.171-178
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• 2002

Chlorophyll (Chl) fluorescence imaging was used to investigate the effectiveness of in vivo incorporation methods for two chemicals, 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) and methyl viologen (MV) in rice, a monocot, and cucumber, a dicot, leaves. four different methods (vacuum infiltration, floating, transpiration-aided incorporation through petiole and spraying) were compared, and $F_i$ and $F_v$/$F_m$ were chosen for the imaging of the DCMU- and MV-treated leaves, respectively. The effects of the chemicals in plants were generally heterogeneous over the whole leaf area. Moreover, the effectiveness of the treatment of a chemical in plant leaves was dependent on chemical species, plant species, concentration of the chemical, the treatment method, the duration of the treatment, the existence of light and detergent, etc. In conclusion, we suggest that to achieve the proposed effects of chemicals in plants for an actual experiment, these factors must be considered before the chemical treatment, and the best method for the treatment of the chemicals tested was floating and vacuum infiltration in the dicot and the monocot leaves, respectively, as drawn from Chl fluorescence imaging analysis.

• Journal of Nutrition and Health
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• 제27권4호
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• pp.356-367
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• 1994

The purpose of this study was to investigate the dietary compliance and related variables in NIDDM patients. One hundred and fourteen patients at two hospitals in Seoul were interviewed and height, body weight, family history and postprandial blood glucose were analyzed statistically along with the dietary practices. 1) When the degree of dietary compliance was expressed as Tunbridge score, 75% was grouped as satisfactory, 9.7% as Tolerable, and 14.9% belonged to Hopeless group. 2) Calorie intake of the subjects was lower then RDA. Carbohydrate, fat, and protein contributed each 60 : 22 :18. When SFA was used 1, the relative ratio of PUFA : MUFA : SFA was 0.8 : 1.2 : 1. 3) The mean score of knowledge test on diet therapy was 5.6$\pm$2.9 out of possible 12.0 points. 4) Age had significant positive correlation with duration of diabetes(p<0.001), and significant negative correlation with scores of knowledge test on diet therapy was observed(p<0.001). 5) The difference of actual and prescribed calorie intake had positive correlation with PP2 blood glucose level(p<0.05), and significant negative correlation with age(p<0.05). 6) Statiscally significant variables on the practice of diet therapy were the present body weight, protein and carbohydrate intake, age, and sex.

• 국제초고층학회논문집
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• 제5권3호
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• pp.167-176
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• 2016

This paper describes a large tuned mass damper (TMD) developed as an effective seismic control device for an existing highrise building. To realize this system, two challenges needed to be overcome. One was how to support a huge mass that has to move in any direction, and the second was how to control mass displacement that reaches up to two meters. A simple pendulum mechanism with strong wires was adopted to solve the first problem. As a solution to the important latter problem, we developed a high-function oil damper with a unique hydraulic circuit. When the mass velocity reaches a certain value, which was predetermined by considering the permissible displacement, the damper automatically and drastically increases its damping coefficient and limits the mass velocity. This velocity limit function can effectively and stably control the mass displacement without any external power. This paper first examines the requirements of the TMD using a simple model and clarifies the constitution of the actual TMD system. Then the seismic upgrading project of an existing high-rise building is outlined, and the developed TMD system and the results of performance tests are described. Finally, control effects for design earthquakes are demonstrated through response analyses and construction progress is introduced.

• 생약학회지
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• 제16권1호
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• pp.18-25
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• 1985

Experimental studies were conducted to investigate for the effect of Tongkyu-tang on analgesic, antipyretic, sedative, anti-inflammatory, isolated ileum and anti-histamine actions. Tongkyu-Tang was composed of sixteen crude drugs including Astragali Radix, which has been used for the treatment of common cold, headache, rhinitis, nasal obstruction, rhincospasm, etc. The following results have been obtained; analgesic and antipyretic actions were obtained. Prolonged action against the hypnotic duration of pentobarbital were significantly noted in mice. Anti-inflammatory effects in the paw edema induced by 1% carrageenin and 1% dextran were significantly shown in rats. Spontaneous motilities of isolated ileum of mice were strongly suppressed, and contractions of isolated ileum of mice and guinea-pigs induced by acetylcholine chloride, barium chloride and histamine were remarkably inhibited. Antihistamine actions were noted. Considering the above experimental results, it is suggested that effects of Tongkyu-tang based on the Oriental Medical References were similarly consistent with the actual experimental results.