• Journal of the Korean Data and Information Science Society
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• 제23권4호
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• pp.787-796
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• 2012

본 연구의 목적은 PAPS를 실시하여 4, 5급에 해당하는 저체력군 학생을 대상으로 16주 복합운동프로그램을 통해 대사증후군과 자율신경계에 어떠한 변화가 나타나는가를 규명하는 것이다. 16주 복합운동프로그램은 주 5회에 걸쳐 준비운동, 본운동, 정리운동으로 구성하고 1회 50분씩 실시하였다. 자료처리는 SPSS 19.0 통계프로그램을 이용하여 모든 종속변인들의 평균과 표준편차를 산출하였다. 샤피로-윌크 검정값을 이용하여 정규성 검정을 실시하였고, 복합운동집단과 통제집단의 모평균 차이를 위하여 독립표본 t-검정을 실시하였으며, 16주 복합운동프로그램 전 후 각 집단 내변인들의 변화를 알아보기 위해 대응표본 t-검정을 실시하였다. 모든 통계치의 유의수준은 ${\alpha}$=.05로 처리하여 다음과 같은 결과를 얻었다. 본 연구 결과 대사증후군 지표에서는 허리둘레, 중성지방, 공복혈당, HDL-C에서 유의한 차이를 나타냈고, 자율신경계 요인에서는 통계적으로 모두 유의한 차이가 나타나 저체력군 고등학생에 긍정적인 영향을 미친 것으로 사료되어 진다.

• 유통과학연구
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• 제17권1호
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• pp.105-115
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• 2019

Purpose - Previous research has shown that a very high level and a very low level of job scope can both be more stressful than intermediate levels of job scope. This study investigates the potential positive and negative effects of the number of accounts handled by sales personnel. The primary objective of this paper is to examine how the number of accounts salespeople handle affects their stress and performance. Research design, data, and methodology - This research conducted the data collection using a survey of salespeople in the pharmaceutical industry. I sent the survey to 420 salespeople, and received 318 usable responses. To assess measurement reliability and validity, I ran an exploratory and confirmatory factor analysis. I also employed structural equation modeling (SEM) to test all hypothesized effects in AMOS and also measured the interaction variable using Ping's (1996) approach. Results - These results show that there are linear and non-linear effects of the number of accounts handled by the salesperson on both role ambiguity and role conflict. First, the number of accounts handled by a salesperson is positively related to role ambiguity and role conflict. Second, the effect of the number of accounts handled on role ambiguity and role conflict decreases as the number of accounts handled by the salesperson increases. Third, as accounts increase from a low level, role stress increases; when the number of accounts reaches an optimal level, role stress decreases; and when the number of accounts increases to a high level, it can be detrimental to the salesperson's role stress. Fourth, while product complexity is positively related to role ambiguity, brand strength is negatively related to both role ambiguity and role conflict. Fifth, the greater the brand strength, the weaker the relationship will be between the number of accounts handled and salesperson role ambiguity. Finally, role ambiguity is positively related to salesperson performance. Conclusion - Too much and too little accounts increase the role ambiguity and role conflict of salespersons. Managers should identify the complex effect of the number of accounts handled by salespeople. Also, when products are complex, managers should provide training to eliminate any complex processes and complex information. These results suggest ways to decrease salespersons' role stress by ensuring an optimal level of the number of accounts and brand strength.

• 한국건설순환자원학회논문집
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• 제11권3호
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• pp.192-201
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• 2023

본 논문에서는 천연 잔골재와 바텀애시 골재를 사용한 다공성 콘크리트의 강도 특성을 분석하였다. 본 연구에서는 천연 잔골재와 바텀애시를 사용하여 각 골재의 재료 특성을 파악 한 후, 다공성 콘크리트의 골재로 사용하였다. 물-바인더 비는 0.25으로 고정하고, 가압다짐 수준을 0.5, 1.5 및 2.5 MPa 값으로 지정하여 다공성 콘크리트 시편을 제작하였다. 단위질량, 초음파속도, 압축강도, 및 휨인장강도를 실험을 진행하고 분석을 수행하였다. 가압다짐 수준이 증가하고, 바텀애시 대비 잔골재 치환율이 증가하면 단위질량, 초음파속도, 압축강도 및 휨인장강도는 증가하였다. 또한, 회귀분석을 통해 다공성 콘크리트의 단위질량과 압축강도 및 휨인장강도의 상관관계를 제시하였다. 단위질량과 강도 특성은 서로 비례하며 증가하는 상관관계를 나타냈다. 또한, 본 연구의 실험별 회귀 분석을 선행연구와 해외 논문의 실험 결과와 비교하여 상관계수(R²) 값을 분석하였다.

• Computers and Concrete
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• 제28권5호
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• pp.521-532
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• 2021

Present paper focuses on the modeling of size effect on the compressive strength of normal concrete with the application of Discrete Element Method (DEM). Test specimens with different size and shape were cast and uniaxial compressive strength test was performed on each sample. Five different concrete mixes were used, all belonging to a different normal strength concrete class (C20/25, C30/37, C35/45, C45/55, and C50/60). The numerical simulations were carried out by using the PFC 5 software, which applies rigid spheres and contacts between them to model the material. DEM modeling of size effect could be advantageous because the development of micro-cracks in the material can be observed and the failure mode can be visualized. The series of experiments were repeated with the model after calibration. The relationship of the parallel bond strength of the contacts and the laboratory compressive strength test was analyzed by aiming to determine a relation between the compressive strength and the bond strength of different sized models. An equation was derived based on Bazant's size effect law to estimate the parallel bond strength of differently sized specimens. The parameters of the equation were optimized based on measurement data using nonlinear least-squares method with SSE (sum of squared errors) objective function. The laboratory test results showed a good agreement with the literature data (compressive strength is decreasing with the increase of the size of the specimen regardless of the shape). The derived estimation models showed strong correlation with the measurement data. The results indicated that the size effect is stronger on concretes with lower strength class due to the higher level of inhomogeneity of the material. It was observed that size effect is more significant on cube specimens than on cylinder samples, which can be caused by the side ratios of the specimens and the size of the purely compressed zone. A limit value for the minimum size of DE model for cubes and cylinder was determined, above which the size effect on compressive strength can be neglected within the investigated size range. The relationship of model size (particle number) and computational time was analyzed and a method to decrease the computational time (number of iterations) of material genesis is proposed.

• 한국해양공학회지
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• 제22권5호
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• pp.52-60
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• 2008

This study investigates the applicability of CADMAS-SURF (Super Roller Flume for Computer Aided Design of a MArtime Structure) code basal on the Navier-Stokes solver to predict bore phenomena. The time variation of ware levels and velocities due to the bore propagation were computed for the different bore strength conditions. In order to verify the numerical results by CADMAS-SURF, laboratory experiments were also performed, using the DPIV and LDV measuring system. The numerical results were compared to the experimental data and the analytical predictions by the NSC method basal on fully nonlinear shallow-water theory by the method of characteristics. It appears that the CADMAS-SURF slightly overestimated the water-surface level measured by the laboratory experiments and its discrepancy becomes prominent as the bore strength increases. The predicted propagation speed for a bore was also slaver than that by the experiment and NSC method. However, the temporal variations in velocities were in relatively good agreement with the experimental data for all cases, except for overshooting and undershooting in the front face of a bore, which may be derived from the numerical instability. Further, CADMAS-SURF successfully simulated the decrease in the water level and velocity caused by the effects of negative waves reflected from the upstream end wall.

• 콘크리트학회논문집
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• 제18권6호
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• pp.793-800
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• 2006

본 연구의 목적은 개발된 황토결합재를 이용한 무시멘트 모르타르의 유동성과 압축강도에 대한 혼화제 재의 영향을 평가하는 것이다. 실험은 혼화제 재의 종류와 치환율에 따라 4그룹으로 분류되어 진행되었다. 시리즈 I은 고성능 감수제의 치환율에 따라, 시리즈 II는 물/황토결합재 비 50%, 60% 및 70%에서 고로슬래그와 팽창시멘트 치환율에 따라, 시리즈 III은 고로슬래그 비표면적과 치환율에 따라, 그리고 시리즈 IV에서는 콘크리트의 경시변화를 위해 개발된 분말형 혼화제인 PSP제의 치환율을 변화시켰다. 실험 결과에 근거하여 무시멘트 황토모르타르의 플로우와 압축 강도 향상을 위한 각 혼화재의 적정 치환율이 제시되었다.

• 동의생리병리학회지
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• 제23권2호
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• pp.426-432
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• 2009

The overall purpose of this study was to investigate the effects of level of isoflavones supplementation on bone metabolism in osteoporosis rats. The effects of level of isoflavones supplementation on calcium and osteocalcin blood level, femur/body weight, bone mineral density(BMD) and bone strength were inspected in this study. This study classified 28 of 12 weeks-old male Sprague Dawley rats which have osteoporosis caused by ovariectomy into four groups of 7 rats and made the subjects medicated them isoflavone. Group I was non-treatment after osteoporosis(control); Group II was low-dose isoflavone(20 mg/kg) feeding after osteoporosis; Group III was middle-dose isoflavone(40 mg/kg) feeding after osteoporosis; Group IV was high-dose isoflavone(80 mg/kg) feeding after osteoporosis; In the calcium and osteocalcin level as one of bone formation indexes, there was a statistically significant difference between the group II, III, IV compared to group I. In respect to the femur/body weight, there was a statistically significant difference between the group II, III, IV compared to group I. In the bone mineral density and bone strength test, there was a statistically significant difference between the group II, III, IV compared to group I. The above results suggests that isoflavone medicated is effective to prevention and treatment of osteoporosis.

• 국제물리치료학회지
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• 제2권1호
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• pp.214-221
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• 2011

The purpose of this study is to investigate and reveal the effects that the complex exercise training consisting of aerobic exercise and strength training(sit up, push up) that everyone can easily practice regardless of a time and a place in order to manage practically the physical strength of the aged affects the difference on their body composition and the change of physical fitness level. Looking into the change of body composition of an experimental group, the weight of 2.5kg was reduced after applying complex training for 12 weeks and the body fat mass of 2.65kg was reduced. Also, the abdominal fat of 0.13% was decreased and the muscle mass of 1.56kg was increased. For the change factors of physical fitness, cardiovascular endurance, muscular strength, muscular endurance, balance and flexibility excluding agility showed significant improvement after applying complex exercise training. The improvement of health fitness of the aged under this study was significantly effective to improve specified body functions which had been lowered by aging and insufficient physical activities. So, it is regarded that their health fitness is the important factor to improve the activity competence required for daily life and to lead healthy living by the improved activity competence. Henceforth, it needs to study more the complex composition of several sports, exercise intensity and the frequency based on the previous researches and studies. In addition, it needs to develop the complex exercise training in accordance with various characteristics such as a sex of the aged, an age, a physical fitness level, environment, a disease and the program in consideration of the efficacy and safety during training.

• 센서학회지
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• 제16권5호
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• pp.325-330
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• 2007

For the application to optic devices, wafer level package including spacer with particular thickness according to optical design could be required. In these cases, the uniformity of spacer thickness is important for bonding strength and optical performance. Packaging process has to be performed at low temperature in order to prevent damage to devices fabricated before packaging. And if photosensitive material is used as spacer layer, size and shape of pattern and thickness of spacer can be easily controlled. This paper presents polymer bonding using thick, uniform and patterned spacing layer of SU-8 2100 photoresist for wafer level package. SU-8, negative photoresist, can be coated uniformly by spin coater and it is cured at $95^{\circ}C$ and bonded well near the temperature. It can be bonded to silicon well, patterned with high aspect ratio and easy to form thick layer due to its high viscosity. It is also mechanically strong, chemically resistive and thermally stable. But adhesion of SU-8 to glass is poor, and in the case of forming thick layer, SU-8 layer leans from the perpendicular due to imbalance to gravity. To solve leaning problem, the wafer rotating system was introduced. Imbalance to gravity of thick layer was cancelled out through rotating wafer during curing time. And depositing additional layer of gold onto glass could improve adhesion strength of SU-8 to glass. Conclusively, we established the coating condition for forming patterned SU-8 layer with $400{\mu}m$ of thickness and 3.25 % of uniformity through single coating. Also we improved tensile strength from hundreds kPa to maximum 9.43 MPa through depositing gold layer onto glass substrate.

• 한국전산구조공학회논문집
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• 제28권5호
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• pp.563-570
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• 2015

기존 구조물의 손상평가에 관한 연구는 지진 등과 같은 과도한 하중에 의한 손상을 고려하였다. 그러나 구조물은 과도한 하중없이도 장기간의 시간에 따라 염화물, 탄성화 등과 같은 이유로 노후화가 진행되어 구조성능이 저하될 수 있다. 그래서 구조물의 건전도를 효과적으로 관리하기 위해서는 노후화에 의한 구조성능 저하도 검토되어야 한다. 본 연구에서는 염화물에 의한 철근의 부식을 노후화 요인으로 고려한다. 철근부식에 의한 재료의 구조성능 저하를 고려하기 위해 부식정도에 따른 철근의 단면적, 항복강도, 파단변형률, 피복 콘크리트 강도 등을 예측한다. 이를 구조모델링에 적용하여 구조부재 및 구조물의 구조성능 저하를 분석한다. 구조부재의 구조성능을 분석하기 위해 모멘트-곡률 해석을 수행한다. 구조물 레벨의 구조성능을 고려하기 위해, 고유치해석을 통한 고유주기와 모드형상을 분석한다. 또한 비선형 정적해석을 통해 구조물의 강도와 변형성능을 분석한다.