• Journal of the Korea Concrete Institute
• /
• v.21 no.3
• /
• pp.347-358
• /
• 2009

Recently, it is getting into a good situation for the flat-plate slab system to be applied. The flat-plate slab without beam, however, is often too weak to control deflection properly compared to other typical slab-beam structures, for which the post-tension method is generally regarded as one of best solutions. The post-tension (PT) method can effectively control deflection without increase of slab thickness. Despite this good advantage, however, the application of PT method has been very limited due to cost increase, technical problems, and lack of experiences. Therefore, in order to reduce difficulties on applying full PT method under the current domestic circumstances and to enhance constructability of PT system, this research proposed the partial PT method with top jacking anchorage applied in a part of span as need. For the top jacking anchorage system, the efficiency of deflection control shall be considered in detail because it can vary widely depending on the location of anchorage that can be placed anywhere as need, and tensile stresses induced at back of the anchorage zone also shall be examined. Therefore, in this study, analysis were performed on the efficiency of deflection control depending on the location of anchorage and on tensile stresses or forces using finite element method and strut and tie model in the proposed top jacking anchorage system. The proposed jacking system were also applied to the floor slabs at a construction site to investigate its applicability and the analysis results of slab behavior were compared to the measured values obtained from the PT slab constructed by the partial PT method. The result of this study indicates that the partial PT method can be very efficiently applied with little cost increase to control deflection and tensile stresses in the region as a need basis where problem exists.

• The Journal of the Korea Contents Association
• /
• v.20 no.3
• /
• pp.678-686
• /
• 2020

The purpose of this study was to compare the physical and psychological functioning by sex, weight and age in Judo athletes. The 124 participants; high school students, college students, and team players. They used physical tests to measure physical examinations by self-describing Knee injury and Osteoarthritis Outcome Score test, Foot and Ankle Outcome Score test, and Oswestry Disability Index, and psychological tests such as Profile of Mood Test, Athletes' Self-Management Questionnaire, and The Athletic Coping Skills Inventory-28, to examine the effects of physical and psychological functions of sports athletes. The physical tests of sex showed differences in knee and back, psychological tests of sex showed differences in mood state, self-management, and athletic coping skills. As a result of physical examination by weight, there was a difference in knee pain and sports items, psychological tests showed that there was a significant difference in mood state except for vitality. Physical examination by age showed differences in knee, ankle, and back. As a result of age-based psychological test, mood state test showed difference in all items except tension and vitality. There was a significant difference only in the items of physical management in self-management test. The results of this study are expected to be used as a basic data for sports injury training and medical technology development by sex, weight and age of Judo athletes.

• Journal of Korean Society of Neurocognitive Rehabilitation
• /
• v.10 no.2
• /
• pp.19-26
• /
• 2018

Many people do not realize that they have poor neck posture. Incorrect forward head posture can lead to turtle neck. This aim to development of specific chair to reduce tension and other symptoms of turtle neck posture. This turtle neck syndrome adjusting chair is a chair that supports the hip and shin of a person to help them correct their posture. It is consisted of the shin support that supports the shin in an angle and the hip support that supports one's hip while the shin is supported at an angle, the main frame that has the two of them connected and the fluid seat that is joined at the top of the hip support and reacts accordingly to the shape of the hip. This is a posture correction chair which has the fluid seat that provides unstable hip support so that it can allow a person to realize their posture from the constant stimulation about the posture. When one seats on the posture correction chair, their hip and shin are supported at an angle that straitens their back, and as their back is straightened, their shoulders and chest are opened, and the neck is positioned at the middle to help them correct their posture. An unbalanced posture causes discomfort to the person seated at the chair, and the person sitting on the posture correction chair will continuously adjust his/her posture to balance the hips to keep the correct posture. Through this process, the person shall adjust his/her left and right posture, ultimately increasing the effectiveness of posture correction. A future collective study on the continuous posture correction of people having turtle neck syndrome using this posture correction chair is required.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.1
• /
• pp.15-29
• /
• 1999

This study presents an analytical method of estimating the developed horizontal active thrusts against GRS-RW( Geosynthetic Reinforced Soil Retaining Wall) system adapted to the case of distanced surcharge. In addition, the design charts that could be used for preliminary design of GRS-RW system are presented. The proposed method of analysis uses two body translation mechanism as well as force polygon concept. taking into account the effect of facing's rigidity. Besides. the effect of tension cracks in c-\Phi$ soils, seismic effects and horizontal distance from the back face of wall to uniformly distributed surcharge loadings are also included. The results of horizontal active thrusts obtained from the developed method of analysis are compared with those from Jarquio's modified Boussinesq equation.

• Journal of Korean society of Dental Hygiene
• /
• v.14 no.3
• /
• pp.381-390
• /
• 2014

Objectives : The purpose of the study is to investigate the relationship between job-stress and temporomandibular joint(TMJ) disorder in dental hygienists. This study will provide the basic data to improve the working condition and the quality of life. Methods : The subjects were 229 dental hygienists at general hospitals in Seoul, Korea. A self-reported questionnaire was filled out from May 20 to June 20, 2013. The questionnaire consisted of 4 questions of demographic features, 11 questions for TMJ symptoms and 5 questions for job stress. The data were analyzed by frequency analysis, chi-square test, Mann-Whitney U test and multiple job-stress logistic regression analysis using SPSS version 21.0. Results : During the last six months, 53.3%(122 persons) of the dental hygienists had TMJ disorder symptoms including joint noise(40.6%, 93 persons), TMJ pain(31.4%, 71 persons) and limitation of TMJ(21.8%, 50 persons). Job-stress is divided into two ranges including high stress group(4.3-5.0 points) and low stress group(0.0-3.6 points) in TMJ pain and joint noise(p<0.05). TMJ pain was closely related to low back pain, pelvis pain and tension headache arising from the uncomfortable working posture. Conclusions : It is necessary to prevent the job stress in the dental hygienists by the improvement of working condition, emotional stability, and frequent postural change.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.2
• /
• pp.107-111
• /
• 2007

A two-dimensional numerical method for inviscid two-fluid flows with evolution of density interface is developed, and an initially stationary two-dimensional fluid sheet surrounded by another fluid is studied. The interface between two fluids is modeled as a vortex sheet, and the flow field with the evolution of interface is solved by using vortex-in-cell/front-tracking method. The edge of the sheet is pulled back into the sheet due to surface tension and a blob is formed at the edge. This blob and fluid sheet are connected by a thin neck. In the inviscid limit, such process of the blob and neck formation is examined in detail and their kinematic characteristics are summarized with dimensionless parameters. The edge recedes at and the capillary wave propagating into the fluid sheet must be considered for better understanding of the edge receding.

• Women's Health Nursing
• /
• v.5 no.2
• /
• pp.162-175
• /
• 1999

The study was intended to investigate and explore the preimenstrual symptoms, their severity levels, their patterns and the relationships of the age to those symptoms and patterns among Korean women. The data were collected from 844 women in one highschool, one Nursing college and one Korea National Open University in Seoul, from Nov, 1997 to Jun. 1998. The instruments were the Menstrual Symptoms Questionnaire developed by Chesney and the Center for Epidemiologic studies Depression scale developed by Radloff. the data were analyzed by descriptive statistics, ANOVA, Duncan's multiple comparison test, $X^2$-test, simple regression analysis and logistic regression analysis using pc-SAS program. The results were as follows ; 1. Korean women had more symptoms of abdominal bloating, fatigue, abdominal discomfort and backache in perimenstrual period. There Teenages had more symptoms of depression and uterine cramps in the day before or the first day of menstruation. Women in their twenties had more symptoms of abdominal pain or abdominal discomfort, backache, abdominal bloating and the sensitiveness /discomforts in the lower back, abdomen and inner part of thighs. women in their thirties had more symptoms of abdominal bloating, fatigue, tension and nervousness before the menstruation, abdominal discomfort and backpain in the first day of menstruation. Women in their forties had more symptoms of backache, breast discomforts, abdominal pain and discomforts. 2. The severity levels of the perimenstrual symptoms showed the highest score(mean=2.73) in twenties and the lowest score)mean=1.96) in forties The perimenstrual symptom patterns were prevailed the spasmodic menstrual symptoms in teenage and twenties and the congestive menstrual symptoms in thirties and forties. The age was a determinant of perimenstrual symptom patterns and the precipitative equation was log[p(age)/(1-p(age)]=2.7356-0.0982 age. 3. The relationship of the age to perimenstrual symptoms was vanished or lessened, controlling for parity as a test factor. this finding supports the notion that parity is an extraneous variable.

• Archives of Plastic Surgery
• /
• v.39 no.5
• /
• pp.457-462
• /
• 2012

Background The elasticity of the back skin of the rat reduced the tension around wounds during the wound healing process in that region, and thus activates wound contraction. The authors proposed two skin fixation methods using readily available materials to decrease the influence of wound contraction on wound healing and designed an experiment to determine their effects. Methods The authors made 36 skin wounds on the backs of 18 rats, and they divided them into three groups. Each group was treated with three different kinds of dressing materials, each with different skin fixing characteristics. Group A was a control group. Group B and group C were dressed by the first and the second skin fixation method. We measured the areas of the wounds post-surgically and calculated the wound area reduction rates. Results The two skin fixation methods both reduced the effect of wound contraction compared to the control group. Each of the two methods had different outcomes in reducing wound contraction. Conclusions The experiment demonstrated significant differences among the wound areas and the wound area reduction rates of the three groups as a result of differences in the degree of wound contraction. To obtain accurate results from wound healing experiments, appropriate skin fixation methods must be adopted.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.10
• /
• pp.1239-1249
• /
• 2013

In this study we establish a process to predict hardening behavior considering the Bauschinger effect for zircaloy-4 sheets. When a metal is compressed after tension in forming, the yield strength decreases. For this reason, the Bauschinger effect should be considered in FE simulations of spring-back. We suggested a suitable specimen size and a method for determining the optimum tightening torque for simple shear tests. Shear stress-strain curves are obtained for five materials. We developed a method to convert the shear load-displacement curve to the effective stress-strain curve with FEA. We simulated the simple shear forward/reverse test using the combined isotropic/kinematic hardening model. We also investigated the change of the load-displacement curve by varying the hardening coefficients. We determined the hardening coefficients so that they follow the hardening behavior of zircaloy-4 in experiments.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.35 no.2
• /
• pp.118-128
• /
• 1999

The shape of the net mouth in a midwater trawl gear is examined by measuring towing speed, gear resistance, the width of otter boards, net height, and so on of a full-scale gear in operation. In addition, a mathematical model is developed to predict shapes of the net mouth. In the model, shapes of head, ground, side ropes, which governs the shape of net mouth, are assumed as a catenary. The validity of the model is tested with observations. The results can be summarized as follows: 1. The warp tension and vertical opening of the gear is highly dependent to the towing speed. The depth of the gear and width of otter boards are very sensitive to the variations of the warp length. 2. The model results indicate that the wing tip of the head and side ropes is reduced and the vertical distances of the head and side ropes sagged to the back with increasing towing speed. 3. The results of comparing the measured net height with calculated side rope height were satisfying. 4. The results of analysis showed the vertical axis of the net mouth was decreased and the width of the net mouth was little changed when the towing speed increased.