• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.44.3-44.3
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• 2019

Massive stars, supernovae, and kilonovae are among the most luminous radiation sources in the universe. Observations usually show near- to mid-infrared (NIR-MIR, 1-5~micron) emission excess from H II regions around young massive star clusters (YMSCs) and anomalous dust extinction and polarization towards Type Ia supernova (SNe Ia). The popular explanation for such NIR-MIR excess and unusual dust properties is the predominance of small grains (size a<0.05micron) relative to large grains (a>0.1micron) in the local environment of these strong radiation sources. The question of why small grains are predominant in these environments remains a mystery. Here we report a new mechanism of dust destruction based on centrifugal stress within extremely fast rotating grains spun-up by radiative torques, namely the RAdiative Torque Disruption (RATD) mechanism, which can resolve this question. We find that RATD can destroy large grains located within a distance of ~ 1 pc from a massive star of luminosity L~ 10^4L_sun and a supernova. This increases the abundance of small grains relative to large grains and successfully reproduces the observed NIR-MIR excess and anomalous dust extinction/polarization. We show that small grains produced by RATD can also explain the steep far-UV rise in extinction curves toward starburst and high redshift galaxies, as well as the decrease of the escape fraction of Ly-alpha photons observed from HII regions surrounding YMSCs.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.1-10
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• 2001

An emergy evaluation of the natural environment ant economy of Seoul revealed that Seoul used 1.27 E23 sej/yr of emergy in 1997. The emergy input from the Han River accounted for most of the renewable emergy sources. Emergy imported from foreign countries and other parts of Korea accounted for 97% of the total emergy use in Seoul in 1997, revealing that the economy of Seoul is more dependent on outside emergy sources than for the entire Korean economy. The emergy use per unit area(2.09 E14 sej/$m^2$/yr) was higher than that for the entire country or Pusan, whereas the emergy use per capita(1.22 E16 sej/person/yr) was lower than that for the entire country or Pusan. These results reflect the overcrowded conditions in Seoul where about one fourth of the Korean population now live. They also seem to indicate a lower living standard in Seoul than the average in Korea. The quality of living in Seoul could also be judged by a high environmental loading ratio and a low sustainability index. All there indices suggest that people in Seoul live under a higher environmental stress than the average person in Korea.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1183-1186
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• 2004

Degradation and insulation failure of traction motor depend on the continuous stress imposed on it. And knowing on insulation condition is important thing for safety operation of EMU(electric multiple unit). In this paper, PD(partial discharge) characteristics for degradation analysis of stator coil is studied. For PD data acquisition, two models are made; one is normal condition coil, the other is aged condition coil. And PD data for discrimination were acquired from PD detector. And these data making use of a computer-aided discharge analyser, statistical and other discharge parameters is calculated to discrimination between different discharge sources. And also these parameter is applied to classify PD sources by neural networks. Neural Networks has good recognition rate for degradation of stator coil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.209-218
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• 2017

This study examined the influence of social support (social support from family, social support from friends), psychological behavioral characteristics (self-esteem, interpersonal dependency, locus of control), and stress on the depression levels of college students. The study subjects were 546 college students in D city. The survey was conducted using a self-administered questionnaire in October 2015. As a result, the depression levels were significantly higher in the group showing lower family and friends' social support, self-esteem, and locus of control, while it was significantly higher in the group showing higher interpersonal dependency and stress. The depression levels of the subjects showed a negative correlation with family and friends' social support, self-esteem, and locus of control, but a positive correlation with interpersonal dependency and stress. Covariance structure analysis revealed an increase in the depression levels of college students when the awareness of the stress source was higher, and when the awareness of social support or psychological behavioral characteristics was lower. These results suggest that the depression levels of college students would be increased when the social support and psychological behavioral characteristics are low, and when stress is high. In particular, it was influenced much more by stress than other factors. Therefore, to decrease the depression levels of college students, it would be necessary to put efforts to understand their main stress sources and then reduce them.

• Journal of Microbiology
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• v.44 no.6
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• pp.689-693
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• 2006

Pbh1, from the fission yeast Schizosaccharomyces pombe, is a baculoviral inhibitor of apoptosis (IAP) repeat (BIR) domain-containing protein. Its unique encoding gene was previously found to be regulated by nitric oxide and nitrogen starvation. In the current work, the Pbh1-lacZ fusion gene was used to elucidate the transcriptional regulation of the pbh1 gene under various carbon sources. When fermentable carbon sources, such as glucose (at a low concentration of 0.2 %), sucrose (2.0 %) and lactose (2.0 %), were the sole carbon source, the synthesis of $\beta$-galactosidase from the Pbh1-lacZ fusion gene was reasonably enhanced. However, the induction by these fermentable carbon sources was abolished in the Pap1-negative S. pombe cells, implying that this type of induction of the pbh1 gene is mediated by Pap1. Ethanol (2.0%), a nonfermentable carbon source, was also able to enhance the synthesis of $\beta$-galactosidase from the fusion gene in wild-type cells but not in Pap1-negative cells. The results indicate that the S. pombe pbh1 gene is up-regulated under metabolic oxidative stress in a Pap1-dependent manner.

• Journal of Microbiology
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• v.41 no.1
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• pp.34-40
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• 2003

Aspergillus nidulans, a homothalic ascomycete, has a complete sexual reproductive cycle as well as an asexual one. Both sexual and asexual development are known to be genetically programmed, but are also strongly affected by environmental factors including nutrients, light, temperature and osmolarity. We have examined these factors to define favored conditions for fruiting body (cleistothecium) formation. In general, fruiting body formation was enhanced where carbon and nitrogen sources were sufficient. Limitation of C-source caused predominant asexual development while inhibiting sexual development. When higher concentrations of glucose were supplied, more cleistothecia were formed. Other carbon sources including lactose, galactose and glycerol made the fungus develop cleistothecia very well, whereas acetate caused asexual sporulation only. Organic nitrogen sources like casein hydrolysate and glycine, and an increase in nitrate or ammonium concentration also enhanced sexual development. In addition to nutrient effects, low levels of aerobic respiration, caused either by platesealing or treatment with various chemicals, favored sexual development. Carbon limitation, light exposure and a high concentration of salts promoted asexual development preferentially, suggesting that stress conditions may drive the cell to develop asexual sporulation while comfortable and wellnourished growth conditions favored sexual development.

• Journal of Korean society of Dental Hygiene
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• v.3 no.1
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• pp.1-12
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• 2003

The purpose of this study was to verify the reliability of the instrument and to analyze the contents of the humor. This study was conducted from December 16th, 2002 to January 13th, 2003, centering on Busan Dental Hospital & public health service. A total of 193 questionnaires was distributed for the survey. The result were as followings: 1. There were significant differences in humor values concerning age(F=1l.44, p=0.000), marriage(t= -3.556, p=0.000), education(F=14.83, p=0.000), clinical carrier(F=9.99, p=0.000), status(F=5.83, p=0.001), working place(F=7.39, p=0.000), and living parents(F=3.65, p=0.014). Humor values were higher for over-forties, married dental hygienists, public health service worker and no living parents. 2. There were no Significant correlation between stress and the dental hygienist's humor values. 3. There were significant differences in humor values concerning sources of the dental hygienist's humor. Data related "book/mass media"(t=-6.32, p=0.000), "conversation" (t=-12.05, p=0.000) and "daily life"(t=-10.33, p=0.000) are examples of these sources. 4. There were no significant differences in humor values concerning the dental hygienist's humor degree related frequency of used humor. 5. There were significant differences in humor values concerning the type of humor used, "word humor"(t=-7.00, p=0.000), "imitation"(t=2.68, p=0.008), "adequate situation" (t=-8.03, p=0.000), "technical terms"(t=6.65, p=0.000) pertain to this. 6. There were Significant differences in humor values concerning the time of using humor expression, "loose situation"(t=-3.75, p=0.000), "tired situation"(t=4.01, p=0.000), "tense situation"(t=5.37, p=0.000), "adequate situation"(t=-16.03, p=0.000) pertain to this.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.469-483
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• 2012

The propagation characteristics of a mechanical wave in human soft tissue depend on its elastic properties. Investigation of these propagation characteristics is of paramount importance because it may enable us to diagnose cancer or tumor from the vibration response of the tissue. This paper investigates and compares displacement patterns generated in soft tissue due to several forms of low-frequency vibration sources placed on a surface. Among vibration sources considered are a normal load, tangential load, and antiplane shear load. We derive analytical expressions for displacements in viscoelastic single layers, and calculate displacement patterns in half space and infinite plate type tissue. Also, we simulate the vibration response of a finite-sized tissue using finite element method. The effects of the type of stress, the size and frequency of vibration sources, and medium boundaries on displacement patterns are discussed.

• BMB Reports
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• v.38 no.5
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• pp.609-618
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• 2005

$\gamma$-Glutamyl transpeptidase (GGT, EC 2.3.2.2.) catalyzes the transfer of the $\gamma$-glutamyl moiety from $\gamma$-glutamyl containing ompounds, notably glutathione (GSH), to acceptor amino acids and peptides. A second gene (GGTII) encoding GGT was previously isolated and characterized from the fission yeast Schizosaccharomyces pombe. In the present work, the GGTII-lacZ fusion gene was constructed and used to study the transcriptional regulation of the S. pombe GGTII gene. The synthesis of $\beta$-galactosidase from the GGTII-lacZ fusion gene was significantly enhanced by NO-generating SNP and hydrogen peroxide in the wild type yeast cells. The GGTII mRNA level was increased in the wild-type S. pombe cells treated with SNP. However, the induction by SNP was abolished in the Pap1-negative S. pombe cells, implying that the induction by SNP of GGTII is mediated by Pap1. Fermentable carbon sources, such as glucose (at low concentrations), lactose and sucrose, as a sole carbon source, enhanced the synthesis of $\beta$-galactosidase from the GGTII-lacZ fusion gene in wild type KP1 cells but not in Pap1-negative cells. Glycerol, a non-fermentable carbon source, was also able to induce the synthesis of $\beta$-galactosidase from the fusion gene, but other non-fermentable carbon sources such as acetate and ethanol were not. Transcriptional induction of the GGTII gene by fermentable carbon sources was also confirmed by increased GGTII mRNA levels in the yeast cells grown with them. Nitrogen starvation was also able to induce the synthesis of $\beta$-galactosidase from the GGTII-lacZ fusion gene in a Pap1-dependent manner. On the basis of the results, it is concluded that the S. pombe GGTII gene is regulated by oxidative and metabolic stress.

• Journal of the Korean Society for Railway
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• v.19 no.1
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• pp.46-53
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• 2016

LED light sources have been known to have a long life and good energy efficiency compared to traditional light sources. Recently, headlamps using LED light sources have ensured the forward visibility and safe operation of high-speed rolling stock. However, assessing the lifespan of LED headlamps based on real test data is not easy because it depends on the multiple stress factors such as a fixed driving current, junction temperature, vibration and so on. Generally, LED headlamps have failed before their advertised life span mainly due to temperature. Thus, the performance assessment of a temperature control unit should be done before a life cycle test of LED headlamps. This study attempted to develop a prototype temperature control module for a lifecycle test system using a commercial LED headlight and verified the system through experiments.