• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
• /
• pp.201-206
• /
• 1993

As the vibration loads are variable and the design criteria are more strict, in this study, the dynamic characteristics of the slab is analyzed and the and the vibration is controlled for the special peculiarity of structures. First, the procedure of dynamic analysis is developed by the finite element method and then examined by using the slab model tests. Second, in order to improve the dynamic characteristics, the effects of the number of supports, material properties, position of exciting force, added mass and dynamic balance on the dynamic behavior of reinforced concrete slabs are analysed. It is concluded that the vibration can be controlled by the change in the natural frequency of system and the use of the high-strength concrete or polymer impregnated concrete (PIC), and the dynamic characteristics can be considerably affected by the arrangement of equipments, added mass, and dynamic balance, etc.

• 대한간호학회지
• /
• 제36권1호
• /
• pp.5-14
• /
• 2006

Purpose: This study was done to analyze the effects of an exercise program on body composition and physical fitness of obese female college students. Method: Data was collected from September 29, 2003 to December, 29, 2003. The research design was arandomized control group pretest-posttest experimental design. The subjects were college nursing students at K University. Forty four students, 20 in the experimental group and 24 ina control group, with more than $30\%$ body fat were randomly assigned. The subjects in the experimental group participated in an exercise program for 12 weeks, sixty minutes per session, five times per week. Body composition and physical fitness was measured by a body composition analyzer, cardiovascular endurance, muscle endurance, muscle strength(grip strength, back strength), flexibility, balance, agility(whole body reaction time) and power(standing long jump). Result: Body weight(F=4.76, p=0.035), body fat(kg)(F=5.68, p=0.022) and body mass index(F=5.73, p=0.021) of the experimental group were significantly different from the control group, but there were no significant differences in body fat($\%$), lean body mass, muscle mass and WHR. Back strength(F=6.50, p=0.015), flexibility(F=14.62, p=0.000), muscle endurance(F=7.98, p=0.007), power(F=5.76, p=0.02l) and balance(F=2.46, p=0.018) of the experimental group were significantly different from the control group, but there were no significant differences in cardiovascular endurance, grip strength or agility. Conclusiton: The exercise program was effective in improving body weight, body fat(kg), body mass index, back strength, muscle endurance, flexibility, balance and power of obese female college students.

• 한국수자원학회논문집
• /
• 제45권2호
• /
• pp.179-189
• /
• 2012

오염물질의 이동 현상을 모의하기 위하여, 감쇠항이 있는 3차원 이송-확산 방정식의 수치모형이 개발되었다. 개발된 모형은 유한차분 모형으로서 시간단계의 가중치 ${\alpha}$를 포함하는 음해법(implicit finite difference method)과, 반복법인 Gauss-Seidel SOR(successive over relaxation)이 사용되었다. 모형은 보다 단순화된 가정 하에서 존재하는 두 가지의 해석적인 해와 비교되었다. 그 결과 Peclet number가 5~20 이하에서는 수치 분산의 영향이 크지 않았고 작은 오차범위 내에서 해석적인 해와 동일하였다. 또한 가중치 ${\alpha}$의 변화에 대한 모형의 거동은 Crank-Nicolson 모형(${\alpha}$=0.5)이 fully-implicit 모형(${\alpha}$=1)보다 해석적인 해에 접근함을 보여주었다. 모형의 검증과 실효성 제고를 위하여, mass balance를 검토하였다. 즉, 이송, 확산 및 감쇠항 각각에 대한 질량 이동을 산출하였으며, 그 결과 질량 이동의 계산 오차는 약 3% 이내였다. 본 모형은 감쇠 과정이 수반되는 3차원 이송-확산의 농도분포와 질량이동을 산출할 수 있으며 다양한 경계조건을 설정함으로서 현장조건을 반영할 수 있다. 그러나본 모형은 고정격자를 기반으로하는 유한차분 모형이므로 Peclet number가 비교적 작게 나타날 수 있는 토양 및 지하수계의 오염물질 이동 등의 문제에서 유용하게 적용될 수 있을 것으로 사료된다.

• 한국환경과학회지
• /
• 제17권10호
• /
• pp.1069-1073
• /
• 2008

Indoor air quality can be affected by indoor sources, ventilation, decay and outdoor levels. Although technologies exist to measure these factors, direct measurements are often difficult. The purpose of this study was to develop an alternative method to characterize indoor environmental factors by multiple indoor and outdoor measurements. Using a mass balance model and regression analysis, penetration factor (ventilation rate divided by the sum of ventilation rate and deposition constant) and source strength factor (source strength divided by the sum of ventilation rate and deposition constant) were calculated using multiple indoor and outdoor measurements. Subsequently, the ventilation rate and $NO_2$ generation rate were estimated. Mean of ventilation rate was 1.41 ACH in houses, assuming a residential N02 deposition constant of 0.94 $hr^{-1}$. Mean generation rate of $NO_2$ was 16.5 ppbv/hr. According to house characterization, inside smoking and family number were higher $NO_2$ generation rates, and apartment was higher than single-family house. In conclusion, indoor environmental factors were effectively characterized by this method using multiple indoor and outdoor measurements.

• 펄프종이기술
• /
• 제37권4호통권112호
• /
• pp.44-51
• /
• 2005

Paper mills use and discharge lots of water. And so now the papermaking industry could be classified into major water consuming industry In order to analyze the process water network and to establish the mass, water balance of duplex board mill, computer aided simulation was made using water pinch method. Based on the pinch analysis results, reuse of process water, after regenerating by microfilter as much as $140\;m^3/hr$, could be suggested without significant accumulation of contaminants in process water. According to this suggestion about $3000\;m^3/day$ of recycled process water could be sub stituted by regenerated water and consequently $30\%$ of energy cost is expected to be reduced.

• 한국환경과학회지
• /
• 제15권10호
• /
• pp.913-918
• /
• 2006

Despite the wide distribution of air pollutants, the concentrations of indoor air pollutants may be the dominant risk factor in personal exposure due to the fact that most people spend an average of 80% of their time in enclosed buildings. Researches for improvement of indoor air quality have been developed such as installation of air cleaning device, ventilation system, titanium dioxide$(TiO_2)$ coating and so on. However, it is difficult to evaluate the magnitude of improvement of indoor air quality in field study because indoor air quality can be affected by source generation, outdoor air level, ventilation, decay by reaction, temperature, humidity, mixing condition and so on. In this study, evaluation of reduction of formaldehyde and nitrogen dioxide emission rate in indoor environments by $TiO_2$ coating material was carried out using mass balance model in indoor environment. we proposed the evaluation method of magnitude of improvement in indoor air quality, considering outdoor level and ventilation. Since simple indoor concentration measurements could not properly evaluate the indoor air quality, outdoor level and ventilation should be considered when evaluate the indoor net quality.

• Mass Spectrometry Letters
• /
• 제5권1호
• /
• pp.30-33
• /
• 2014

A solid phase extraction (SPE) method was optimized for the quantitative analysis of perfluorooctanoic acid (PFOA) in serum using hydrophilic-lipophilic balance SPE and LC-MS/MS. Fetal bovine serums spiked with $^{13}C_8$-PFOA before or after SPE were used as test samples for evaluation of the SPE efficiency. Simultaneous evaluation of matrix effects and absolute SPE recovery for $^{13}C_8$-PFOA in serum using different sample pre-treatments and SPE conditions allowed optimization of SPE process efficiency with minimal matrix effect and decent SPE recovery. Introduction of protein precipitation as a sample pre-treatment procedure for serum samples before SPE generally decreased matrix effect in LC-MS/MS analysis and provided more stable recovery of PFOA.

• 대한기계학회논문집
• /
• 제18권8호
• /
• pp.1952-1966
• /
• 1994

The body segment parameters of twelve young male Korean were measured to compare with the results of foreign cadaver studies. A human body was assumed to have fourteen body segments. The mass of each segment was measured with a water immersion test and the mass center of a segment was determined on the balance platform by changing postures. In the case of Korean, because of the difference in body proportion, the mass center of whole-body is located further from the distal end of head(Korean : 44.9% vs. Caucasian : 41.2%), and the mass center of each segment also located in different proportional locations. The existing regression equations, which can estimate segment mass based upon the anthropometric dimensions, estimates segment mass (the mass of shank) for Korean with 13% error. Therefore, it is not recommended to estimate the mass, and the moment of inertia of body segment of Korean based on the existing equations. However, the density information of body constituents was similar enough to apply it to Korean density. It was validated by the comparison between the results of the direct immersion method and 3-dimensional volume reconstruction of segment form the cross sectional images of CT-scan. The average body density measured form twelve subjects was $1.035{\;}kg/m^3$ and showed deceasing trendency.

• Design & Manufacturing
• /
• 제17권4호
• /
• pp.57-62
• /
• 2023

As a representative method for mass production, a multi-cavity type mold capable of simultaneously molding products of the same shape can be applied. It has the advantage of improving the productivity from several times to several tens of times, but it may cause disadvantages which is the quality deviation with each cavity. This study, therefore, has tried to increase the cavity filling balance by using a melt flipper and a flow distance control part in the runner part of the mold. Along with this, the design and manufacturing of air vents during injection molding have been verified through experimental methods to achieve a higher level of multi-cavity filling balance and dimensional accuracy.

• 대한물리치료과학회지
• /
• 제22권1호
• /
• pp.11-17
• /
• 2015

Purpose : The current study examines changes of static uprighting balance in the visual input characteristics. Method : Total 50 person(male 16, female 34) were participated in this study. They were tested with 'hole in the card' for identification of dominant eye's side, then they were divided 3 groups(both visual input group, dominant visual input group, and non-dominant visual input group). 3 groups were measured with Romberg test on the force platform device to compare the static uprighting balance characteristics ; moving distance, mean velocity, and sway area of the CoM(center of mass), during 20 seconds. Results : The results by one-way repeated measure ANOVA were as follows. In moving distance and mean velocity of CoM, non-dominant visual input group was unstable than dominant visual group and both visual input group(p<0.05). But, in sway area of CoM, significant difference was not existed statistically. Conclusion : These result can be applied to design the static uprighting balance program using visual input mediation.