• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.4 s.152
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• pp.607-614
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• 2006

This study was carried out to suggest the optimal spinning process condition which provides a proper range of tenacity and biodegradability as textile fibers. The effects of the melt spinning speed and heat treatment on the mechanical property and biodegradability of polylactic acid fiber were investigated. Polylactic acid(PLA) was spun in a high spinning speed of $2000{\sim}4000m/min$. Each specimen was heat-treated at $100^{\circ}C$ during 30min. Mechanical properties such as breaking stress and the degree of crystallinity were evaluated using WAXS. Biodegradability was estimated from the decrease of breaking stress, weight loss, and the degree of crystallinity after soil burial. Experimental results revealed that heat treated specimens showed higher breaking stress than untreated specimens, but the increase was not so high as was expected from the remarkable change of crystallinity by heat treatment. It was concluded that breaking stress was more influenced by spinning speed than heat treatment. In the soil burial test, however biodegradability calculated from weight loss was more influenced by heat treatment than spinning speed.

• Proceedings of the KSAR Conference
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• 2001.10a
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• pp.47-47
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• 2001

One of the problems associated with in vitro culture of primordial germ cells (PGCs) is the large loss of cells during the initial period of culture. This study characterized the initial loss and determined the effectiveness of two classes of apoptosis inhibitors, protease inhibitors and antioxidants, on the ability of porcine PGCs to survive in culture. Results from electron microscopic analysis and in situ DNA fragmentation assay indicated that porcine PGCs rapidly undergo apoptosis when placed in culture. Additionally,？ 2-macroglobulin, a protease inhibitor and cytokine carrier, and N-acetylcysteine, an antioxidant, increased the survival of PGCs in vitro. While other protease inhibitors tested did not affect survival of PGCs, all antioxidants tested improved survival of PGCs (p〈0.05). Further results indicated that the beneficial effect of the antioxidants was critical only during the initial period of culture. Finally, it was determined that in short-term culture, in the absence of feeder layers, antioxidants could partially replace the effect(s) of growth factors and reduce apoptosis. Collectively, these results indicate that the addition of ？2-macroglobulin and antioxidants can increase the number of PGCs in vitro by suppressing apoptosis.

• Journal of the Korea Institute of Building Construction
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• v.13 no.1
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• pp.38-47
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• 2013

When building with concrete in cold weather, an insulation method of heat curing must be determined, and a holistic curing plan that considers the characteristics of structures, the heat loss coefficient of a curing sheet, the joint condition of the curing materials and the quantity of heat produced by a heating apparatus is an essential prerequisite for protection against early frost damage. But on a number of national construction sites, there have been serious problems in cold weather concreting due to the unreliability of the information obtained from practical experience. In the construction field in Japan, there is a specification for heat curing prepared by Japanese Architectural Society, which provides an equation for calculating heat quantity. It is also necessary to adopt a detailed specification for a standard heat curing method that is applicable to all national construction sites. In this study, the effect of bubble sheets on the economic feasibility of cold weather concrete is investigated through a comparison with the blue sheets commonly prescribed in national construction sites. In conclusion, this study found that bubble sheets had the effect of reducing the cost of curing materials and the fuel cost consumed by a heating apparatus, compared to the use of blue sheets.

• Journal of Periodontal and Implant Science
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• v.31 no.4
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• pp.803-810
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• 2001

The purposes of this study were to investigate the relationship between cigarette smoking levels and periodontal status. 199 subjects, consisting of male 127 and female 72, classified by smoking levels and duration were selected: Patients who had smoked for more than 20 cigarettes/day were considered heavy smokers, 10 to 19, moderate smokers; 1-9, light smokers:0, non-smoker. And smokers were divided into ones who had smoked for more than 20 years, 10-19 years, less than 10 years and non-smokers. Heavy smokers and moderate smokers showed significantly greater pocket depths, less clinical attachment levels, more molar furcation involvements, greater alveolar bone loss and higher scores of plaque index than light smokers and non-smokers,(p < 0.05). When the duration of smoking was considered as a factor, scores of clinical parameters were worse and alveolar bone loss were significantly greater in long-term smokers, who had smoked for more than 20 years. In conclusion, cigarette smoking is associated with periodontal status.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.113-120
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• 2008

Potential application of the scroll type machine to air compressor for fuel cell has been studied. Among the seven configuration factors which determine scroll wrap profile, the wrap thickness and the orbiting radius were chosen as two independent variables to generate various scroll wrap profiles. A conceptual design practice was conducted for scroll air compressor for SOFC with power output of 2 kW. With larger wrap thickness and orbiting radius, base plate area of the orbiting scroll becomes smaller, so is the axial gas force acting on the base plate, resulting in reduced thrust loss in spite of larger friction velocity. Performance analysis on the designed model showed that its total efficiency was 64.4% with the mass flow rate per unit compressor input of 0.00905 kg/(s kW) for the wrap thickness of 3.5 mm and the orbiting radius of 3.0 mm.

• Journal of the Korean Physical Therapy Association
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• v.13 no.1
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• pp.5-17
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• 1992

Depression in Spinal Cord Injury Patients Kang, Soon Hee, M.Ed., R.P.T. Dept. of Rehabilitation Medicine, Kyung-Hee University Medical Center Depressions have the potential to affect adversely the rehabilitation of patients with spi-nal cord iniury. The present study examined depression, functional independence, and demographic and medical characteristics for 49 spinal cord injury(SCI) patients. This investigation involved the administration of the Beck Depression Inventory, the Modified Barthel Index, and aquestionnaire consisted of 14 items, The results were as follows .1. Compared to normal subjects, SCI patients had significantly higher BDI scores.2. When the cut-off point of HDI scores was assumed 21, 26.1% of normal subjeets and 75.5% of SCI patients appeared to be depressed. Depression in SCT patients were not related with age, sex, marital status, injury evel, severity, duration, pain, functional independence and medical charge. Depression in SCI patients were related with education level, economic level, age at injury, motivation. Depression in normal subjects were related with age, education level, economic level, but not related with sex, marital status. There were significant differences at 30 items of BDI between normal subjects and SCI patients. The items were as fellows . 1 sadness, 2 pessimism, 3 failure, 4 dissat-isfaction, 5 guilt, 6 punishment. 7 self-dislike 9 suicidal, 10 crying, 11 irritability, 12withdrawl, 13 indecisive, 14 self-image, IS work inhibition, 16 insomnia, 17 fatigue,18 anorexia, 19 weight loss, 20 hypochondria, 21 libido loss.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.110-116
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• 2015

In this paper, a compact low-loss reflector-type phase shifter with harmonic suppression using meander T-shaped branch-line coupler is suggested. The compact coupler for the phase shifter has a size of $22.2{\times}14.9mm^2$ while a conventional branch coupler has a size of $32.6{\times}27.8mm^2$. The phase shifter shows insertion losses of 0.19-0.28 dB at the center frequency of 2.1 GHz, and a measured maximum phase shift of $137^{\circ}$.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.5
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• pp.299-304
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• 2018

An ideal circuit breaker should supply electric power to loads without losses in a conduction state and completely isolate the load from the power source by providing insulation strength in a break state. Fault current is relatively easy to break in an Alternating Current (AC) circuit breaker because the AC current becomes zero at every half cycle. However, fault current in DC circuit breaker (DCCB) should be reduced by generating a high arc voltage at the breaker contact point. Large fire may occur if the DCCB does not take sufficient arc voltage and allows the continuous flow of the arc fault current with high temperature. A semiconductor circuit breaker with a power electronic device has many advantages. These advantages include quick breaking time, lack of arc generation, and lower noise than mechanical circuit breakers. However, a large load capacity cannot be applied because of large conduction loss. An extinguishing technology of DCCB with polymeric positive temperature coefficient (PPTC) device is proposed and evaluated through experiments in this study to take advantage of low conduction loss of mechanical circuit breaker and arcless breaking characteristic of semiconductor devices.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.100-105
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• 2004

Installed capacity markets in the northeast of the United States ensure that adequate generation exists to satisfy regional loss of load probability (LOLP) criterion. LOLP studies are conducted to determine the amount of capacity that is needed, but they do not consider several factors that substantially affect the calculated distribution of available capacity. These studies do not account for the fact that generation availability increases during periods of high demand and therefore prices, common-cause failures that result in multiple generation units being unavailable at the same time, and the negative correlation between load and available capacity due to temperature and humidity. A categorization of incidents in an existing bulk power reliability database is proposed to analyze the existence and frequency of independent failures and those associated with resource dynamics. Findings are augmented with other empirical findings. Monte Carlo methods are proposed to model these resource dynamics. Using the IEEE Reliability Test System as a single-bus case study, the LOLP results change substantially when these factors are considered. Better data collection is necessary to support the more comprehensive modeling of resource adequacy that is proposed. In addition, a parallel processing method is used to offset the increase in computational times required to model these dynamics.

• The Korean Journal of Community Living Science
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• v.22 no.4
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• pp.637-653
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• 2011

Over the last 20 years, women's development has been ambiguous. According to Freud, the mother-daughter relationship has been considered as an essential component of women's development. This study investigated how the mourning experience from daughters who were separated from their mothers by death offers any meaningful idea to women's life. For Hermeneutic phenomenology, researchers collected data from three women who have lost their mothers through in-depth interviews and drawing pictures with each of them. As a result, this study found that daughters started to fight with their mothers' death from the moment when they were informed. They also experienced a symbolic death until the moment of their mothers' death and even after the confirmation of their mothers' death. Daughters experienced symbolic death, both emotionally and physically as well as familiar experiences with their mothers through the repeated confirmation of death. However, these experiences encouraged daughters to adapt to the reality that was the absence of their mothers through the processes such as "Reflection," "Living in the Center of My life," and "Another Embrace." Through this new perspective, attempts, and relationships, daughters form a new identity and experience 'rebirth'. These daughters' changes were paradoxically strengthened through their resistances towards changes of reformation of themselves.