• Physical Therapy Korea
• /
• v.13 no.3
• /
• pp.102-110
• /
• 2006

To improve trunk stability, various exercise protocols were introduced into the clinical field. Trunk and lumbar stability exercises on unstable surfaces are especially recommended to improve lumbar stability. The purpose of this study was to compare abdominal oblique muscle activity during leg raising in hook-lying position among 3 different type of surface conditions (on floor (F), vestibular board (VB), and foam roll (FR)). Sixteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. Surface electromyography (EMG) activity was recorded from the internal and external oblique muscles of both sides. The normalized EMG activity was compared using a one-way repeated ANOVA. The results showed that the EMG activities of the internal oblique and external oblique of the lifted leg side during straight leg raising significantly increased under the FR condition when compared to the F condition. There was no significant difference of the EMG activity in abdominal oblique muscles between the VB and the FR conditions. The EMG activity of the internal oblique of supported leg side during the straight leg raising was significantly greater under the FR condition than the VB and F conditions (p<.05). The composition ratio of EMG activity of internal oblique muscles during straight leg raising was significantly increased under the FR condition. Therefore, straight leg raising exercise on foam roll in hook lying position could be beneficial to improve trunk and lumbar stability.

• Journal of the Microelectronics and Packaging Society
• /
• v.10 no.1
• /
• pp.45-50
• /
• 2003

Global full 3D finite element analysis fatigue models are constructed for flip-chip BGA on system board to predict the creep fatigue life of solder joints during the thermal cycling test. The fatigue model applied is based on Darveaux's empirical equation approach with non-linear viscoplastic analysis of solder joints. The creep life was estimated the creep life as the variations of the four kinds of thermal cycling test conditions, pad structure, composition and size of solder ball. The shortest fatigue life was obtained at the thermal cycling test condition from $-65^{\circ}C$ to $150^{\circ}C$. It was increased about 3.5 times in comparison with that from $0^{\circ}C$ to $100^{\circ}C$. At the same conditions, the fatigue life of SMD structure as the change of pad structure increased about 5.7% as compared with NSMD structure. Consequently, it was confirmed that the fatigue life became short as the creep strain energy density increased in solder joint.

• Journal of Welding and Joining
• /
• v.24 no.6
• /
• pp.21-27
• /
• 2006

This study was focused on the evaluation of the thermo-mechanical board-level reliability of Pb-bearing and Pb-free surface mount assemblies. The composition of Pb-bearing solder was a typical Sn-37Pb and that of Pb-free solder used in this study was a representative Sn-3.0Ag-0.5Cu in mass %. Thermal shock test was chosen for the reliability evaluation of the solder joints. Typical $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed between both solders and Cu lead frame at the as-reflowed state, while a layer of $Cu_3Sn$ was additionally formed between the $Cu_6Sn_5$ and Cu lead frame during the thermal shock testing. Thickness of the IMC layers increased with increasing thermal shock cycles, and this is very similar result with that of isothermal aging study of solder joints. Shear test of the multi layer ceramic capacitor(MLCC) joints was also performed to investigate the degradation of mechanical bonding strength of solder joints during the thermal shock testing. Failure mode of the joints after shear testing revealed that the degradation was mainly due to the excessive growth of the IMC layers during the thermal shock testing.

• Fire Science and Engineering
• /
• v.14 no.2
• /
• pp.33-38
• /
• 2000

Flux, essentially used in soldering process of PCB (Printed Circuit Board) in electronics industry, contains IPA (Isopropyl alcohol) and methanol, which are highly inflammable and explosive. Hazard Chemical Controlling Law classified methanol as toxic material and Environmental Law classified methanol as VOC (Volatile Organic Compound). So there have been pressing needs of developing substitutes for the existing Flux. New solvent which is non-flammable and main component is DCP having same specific character of the existing Flux. It's been combirated with proper composition ratio adding stabilizer. As a result, it relieved working Environment Allowance thickness 200 ppm to 470 ppm, chance of not been soldered 0.083% to 0%, spread 85% to 87%, power saving resistance 1.0$\times$$10^{12}$$\Omega$ to 6.9$\times$$10^{12}$$\Omega$, which means a lot better than the existing Flux. Therefore, Flux confirmed the chance of improving productivity, safety, environment safety and quality. Also, Flux got a satisfied result after product quality test and product reliability test.

• Journal of Korean Medicine for Obesity Research
• /
• v.8 no.2
• /
• pp.49-62
• /
• 2008

Objectives Physical activity is known to be beneficial to prevent weight gain and to be physically healthy. In this study, we tried to find out the relationship between body composition with physical activity. Methods International Physical Activity Questionnaire(IPAQ)-short form was given to premenopausal women aged 20~55 and BMI${\geq}23\;kg/m^2$. Subcutaneous and visceral adipose tissue of the subjects by CT scanning was obtainedin a single slice. They were given written consent and this study is performed under the permission of institutional review board of Kyung Hee East-west Neo Medical Center. Results The mean of physical activity of total subjects was 1935.18 MET-min/week(n=63). When three groups of physical activity pattern(inactive, minimally active, and HEPA(Health-enhancing physical activity) active) was analyzed, all of them were heavily relied on the activity intensities of walking. The VSR(visceral/Subcutaneous adipose tissue Ratio) was correlated with total physical activity in vigorous activity group. Conclusions The physical activity of Korean obese and overweight women was on the average, but the vigorous activity is thought to be necessary. The vigorous physical activity was related with visceral adipose tissue.

• Resources Recycling
• /
• v.15 no.1 s.69
• /
• pp.3-11
• /
• 2006

Fast pyrolysis of Quercus acutissima was carried out in a fluidized bed pyrolyser and then the physicochemical properities of obtained bio-oil were analyzed using GC/MS. The yields of bio-oil of Quercus acutissima and Larix leptolepis from a fluidized bed pyrolyzer were maximized at $350^{\circ}C\;and\;400^{\circ}C$, respectively. This is due to the difference or cellulose content between the two tree species. Above the optimum temperature, the yields of char and oil decreased as the reaction temperature increased, but the yield of gas-phase and water fraction increased. It is concluded that this phenomenon is occured by secondary pyrolysis in the free board. The feeding rate of the sample in a fluidized bed pyrolyser did not affect the yields and composition of products, because of a sufficient mixing between bed materials and sand.

• Resources Recycling
• /
• v.17 no.2
• /
• pp.16-29
• /
• 2008

According to the statistical data of the Ministry of Environment, 47million tons of construction waste were generated, and 96.7% of them was recycled in 2005. However, the recycled products seem to be remained under low quality. Because mixed demolition and construction waste, so called DC Waste, including concrete, brick, plaster, lumber, plastics building materials, paper and some dirt and stone, is very variable and difficult to estimate its exact composition, it is regarded as having little or no value to the construction industry. 'The Research group on recycling of construction waste' was started by the Housing & Urban Research Institute(KNHC), which is sponsored as a large scale national project by the Ministry of Construction and Transportation. This research group intends to establish recycling system through planing, processing, developing practical technology, and eventually contribute to save natural resource and to vitalize the industry. In this paper an overview of DC waste management and recycling technology is given in some detail. Particularly, "recycling law of construction waste" and recent research trends on recycling of construction waste are discussed.

• Journal of Korea Game Society
• /
• v.4 no.1
• /
• pp.3-13
• /
• 2004

On today, online community that is irrespective to geometrical area and time has been appeared by information technology and development of internet. It has been significant decision method of a personal and company. And online community is variously classified by it's purpose. Among online community, online game community is be roughly classed as community in online game and community in related online game. Community in related online game community is means for interchanging informations using e-mail, bulletin board, so as on. These information contain game playing, game contents so as on. And community in online game is implemented as team, item exchange, chatting etc. Importance of community in online game and community in related online game have been increased. But online game community is not distinguished, comparing with importance of it. So, in this paper, we study on the case analysis of cyworld's community that developed characteristic community. Cyworld community is suitable for new generation and korean life style, method of adaption online game. This paper should be profitable for community in re lated online game, community company to planning, developing a characteristic community.

• Journal of the Korean Wood Science and Technology
• /
• v.23 no.2
• /
• pp.55-69
• /
• 1995

The primary objective of this research was to investigate optimum manufacturing condition of thin composite panels composed of sawdust, polyethylene film and polypropylene net. At the study the experiment was designed to make thin board in which sawdust offers effectiveness as core composing material, polyethylene as adhesive with added urea resin, and polypropylene as stiffness and flexibility in the composition panel. 100 types of thin composite panels were manufactured according to press-lam and mat-forming process of various hot pressing conditions(pressure, temperature and time). They were tested and compared with control boards on bending properties(MOR, MOE, SPL, WML), internal bond strength, thickness swelling, linear expansion and water absorption. At the same time the visual inspections of each types of panels were accomplished. The physical and mechanical properties of composite types passed by visual inspection were analyzed by Tukey's studentized range test. From the statistical analysis, the optimum manufacturing condition of thin composite panels were selected. Compared with two manufacturing processes, mat-forming process performed better than press-lam process in all tested properties. The optimum manufacturing conditions resulted from the experiment and statistical analysis were able to determine as following: the press temperature was shown the most good result at 130$^{\circ}C$ in mat forming process and 140$^{\circ}C$ press lam process, the press time 4 min in both processes, but the press pressure was 25-10kg/$cm^2$ in mat forming and 15k/$cm^2$ press lam process.

• Journal of Families and Better Life
• /
• v.10 no.2
• /
• pp.19-36
• /
• 1992

The purpose of this paper is to analyze empirically the tendency of household consumption expenditure according to the change of social and economical condition, and the factor which influences consumption expenditure of urban household. The data used in analysis are time-series. The data are statistic form Urban Household Economy Survey published by the Economic Planning Board, dating form the first quarter of 1970 to the fourth quarter of 1989. The income of household and consumption expenditure materials were deflated as consumer price index to exclude the influence of prices and the influence of household composition are considered to deflated as the size of the household under assumption of homogeneity. The consumption expenditure items were categorized to 12 relatively large range items. The time-series data were analyzed by using the Two Stage Least Squares and the Ordinary Least Squares. The following is the result of analysis. 1) Rather than the income increase of previous years. the average income increase for two years influences more significantly on consumption expenditure of household. In the case of influence on consumption expenditure for each item by increase in disposable income, such categories as furniture and utensils. clothing and footwear, housing, medical care, culture and recreation, and transportation and communication have significant influence. 2) Among consumption expenditure categories, the increasing factors were furniture and utensils, and clothing and footwear. And the decreasing factors were housing, medical care, culture and recreation ,and transportation and communication. The relative prices, however, had significant influence on categories such as housing, furniture and utensils, medical care , culture and recreation, and transportation and communication and all of them were the decreation factors. 3) Among with changes of social and economical conditions, miscellaneous showed the highest increase in marginal propensity to consume and foods was the lowest. Also culture and recreation and housing brought up a great change of the income elasticity of demand.