• Journal of Digital Convergence
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• v.15 no.9
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• pp.487-495
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• 2017

The purposes of this study were to find smart-phone addiction how to mediate between worker's stress, anxiety and work commitment. The subject of survey was 329 workers in a public cooperation, and the data were analyzed by AMOS 18.0. The major findings were as follows; First, the higher the stress and anxiety, the more the direct effect on smartphone addiction. Second, smartphone addiction showed a significant negative relationship with work commitment. Third, smartphone addiction played a mediating role in the relationship between stress, anxiety, and work commitment. Workers with high levels of stress and anxiety were over-dependent on smartphones, which resulted in a decrease in work commitment. In order to prevent the problem of smartphone addiction of workers, it is necessary to prepare guidelines for correct use of smartphone in the workplace and service support should be provided according to the level of addiction. In addition, in order to improve work commitment, active support from the aspect of corporate welfare is needed to manage stress well. Finally, this study has a policy implication in that it reveals the route leading to smartphone addiction.

• Korean Journal of Cleft Lip And Palate
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• v.13 no.1
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• pp.23-28
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• 2010

대한악안면성형재건외과학회는 2004년도부터 매년 인도적 차원에서 의료 환경이 낙후된 Vietnam의 cleft lip and palate 환자들을 치료하기 위해 무료로 해외 진료 봉사 활동을 해왔다. 초창기 해외 진료 봉사 활동 당시 베트남 의료 기술 발달이 미비하여 준비해야 할 것들이 많았으나 이 후 베트남의 경제 발전과 함께 의료 시설 및 의료 기술이 발달함에 따라 준비 품목 등이 간단명료해지고 현지 지원 및 수술 준비도 원활히 진행되었다. 이러한 무료 의료 봉사 활동을 계기로 개발도상국의 낙후된 의료 시설 및 의료 기술 발전, 의료 혜택을 받지 못한 구순 구개열 환자의 정상적 안모 및 기능 회복, 조건 없는 의료 봉사 활동을 통한 민간외교 효과 및 양국간의 우호 증진 등의 성과가 있었다. 대한악안면성형재건외과학회에서는 2009년도 역시 베트남 National Institute of Odonto-stomatology 에서 11월17일부터 26일까지 cleft lip and palate 무료수술진료단(단장 신효근)을 보내 수술봉사 활동을 펼치고 돌아 왔다. 일반적인 구순구개열 뿐만 아니라 양측성 안면열(Bilateral Facial Cleft), 사경(Torticollis) 등의 희귀 기형을 포함하여 수술을 진행하였으며 총 31례의 수술을 성공적으로 마쳤으며 지난 6년 동안의 성과와 함께 이에 대한 보고를 하고자 한다.

• Journal of Ginseng Research
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• v.33 no.4
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• pp.349-354
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• 2009

This study was conducted to develop a new method for enhancing ginsenoside $Rg_3$, which is abundant in black ginseng. The cognition-enhancing effect of black ginseng extract was investigated via the assay of acetylcholinesterase (AChE) activity. Black ginseng I was prepared through the traditional method (by steaming and drying nine times repetitions). Black ginseng II, on the other hand, was prepared by steaming the ginseng three times at $120^{\circ}C$ for 30 min after soaking it in grape juice for 24 h. The ginsenosides of white, red, and black ginseng I, and II were investigated using the HPLC method, respectively. In black ginseng II, the ginsenoside $Rg_3$ contents, which cannot be found in white ginseng, amounted to 10.91 mg/g, approximately 18 times more than that in red ginseng. In the in-vivo study, black ginseng extract (200 mg/kg, p.o.) inhibited the AChE activity after 24 h by a single administration in the brain. Thus, the new manufacturing method for black ginseng was found to more effective in the conversion of ginsenoside $Rg_3$ compared to the traditional method. Black ginseng may also have the effect of preventing the cognitive impairment induced by cholinergic dysfunction.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.473-481
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• 1999

This study evaluated the shear bond properties of IPS Empress glass ceramic to enamel and dentin surfaces with three ceramic surface treatments, and three resin cements. The influence of thermocycling was also investigated. The purpose of this study was to investigate the influences of resin cements, ceramic surface treatments, and thermocycling on shear bond properties. Ninety freshly extracted, noncarious human molars were selected for this study. The surface treatments of ceramic were etching <5.0% hydrofluoric acid, application of silane coupling agents(Tokuso Ceramic Primer, Clearfil porcelain bond, Monobond-S), and the combination of the two methods. Empress cylinders were bonded to enamel and dentin surfaces with three kinds of resin cements(Bistite resin cement, Panavia 21, Variolink). The specimens were aged in $37^{\circ}C$ distilled water for 24 hours. Half of the specimens were then thermocycled 500times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 15 seconds. Each specimen was debonded in shear mode and measured shear bond properties by using the universal testing machine(Zwick 020, Germany). The data were analyzed by SPSS/PC+(one-way ANOVA, Scheffe' s test and t-test). The results were as follows : 1. Without thermocyling, there was significant difference of shear bond strength to enamel surface between Bistite Resin Cement and Panavia 21 in case of etched and silane-treatment(p<0.05). 2. Without thermocyling, the shear bond strength of a group treated with silane and etching was significantly higher than that of a group treated with silane or etching with the application of Panavia 21 and Variolink(p<0.05). 3. A group treated with etching with the application of Variolink only showed a decrease of shear bond strength after thermocycling(p<0.05).

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.465-472
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• 1999

The aim of this study was to determine the shear bond properties of four dentin bonding systems to internal cervical dentin, and to investigate the effect of the pretreatment for removing smear layer and position of dentin on shear bond strength of dentin bonding agents. The materials tested in this study were consisted of four commercially available dentin bonding systems[Allbond 2(AB), Clearfil Linerbond 2(CL), Optibond FL(OP), Scotchbond Multi-purpose(SB)], a restorative light-cured composite resin[Z100]J and a chelating agent[RC-prep(RC)]. Fifty-six freshly extracted human molars were used in this study. Dentin specimens were prepared by first cutting the root of the tooth 1mm below the cementoenamel junction with a diamond bur in a high speed handpiece under air-water coolant, and then removing occlusal part at pulp horn level by means of a second parallel section, The root canal areas were exposed by means of cutting the dent in specimens perpendicular to the root axis. Dentin specimens were randomly assigned to two groups(pretreated group, not-pretreated group) based on the pretreatment method of dentin surface. In pretreated group, RC was applied to dentin surface for 1minute and then rinsed with NaOCl. In not-pretreated group, dentin surface was rinsed with saline Each groups were subdevided into four groups according to dentin bonding systems. Four dentin bonding systems and a restorative resin were applied according to the directions of manufacturer. The dentin-resin specimens were embedded in a cold cure acrylic resin, and were cut with a low speed diamond saw to the dimension of $1{\times}1mm$. The cut specimens were divided into three groups according to the position of internal cervical dentin. The shear bond properties of dentin-resin specimens were measured with Universal testing machine (Zwick, 020, Germany) with the cross head speed of 0.5mm/min. From this experiment. the following results were obtained : 1. In case of shear bond strength, there was no significant difference among dentin bonding systems in not-pretreated groups, whereas in pretreated groups, the shear bond strengths of AB and of SB were statistically significantly higher than those of CL and of OP. 2. The shear bond strengths of AB and of SB in pretreated groups were significantly higher than those in not-pretreated groups. 3. The shear bond strengths of radicular layer of OP were higher than those of occlusal layer of OP in not-pretreated groups, and of AB in pretreated groups. The shear bond strengths of radicular layer of AB and of CL in not-pretreated groups were higher than those in pretreated group.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.751-760
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• 1997

Resin-modified glass ionomers were introduced in 1988 to overcome the problems of moisture sensitivity and low early mechanical strengths of the conventional glass ionomers, and to maintain their dinical advantages. The purpose of this study was to evaluate the bi-axial fracture strength of four resinmodified glass-ionomers(Fuji II LC, Vitremer, Dyract, VariGlass), one resin composite material(Z-100), and one conventional glass-ionomer(Fuji II). Three specimens of each material and shade combination were made according to the manufacturers' instructions. Materials were condensed into metal mold with a diameter of 10mm and a thickness of 2.0mm and pressed between two glass plates. Resin-modified glass ionomers were polymerized using a Visilux II light curing unit by irradiating for 60 seconds from both sides, and conventional glass ionomer was cured chemically. After specimens were removed from the molds, surfaces were polished sequentially on wet sandpapers up to No. 600 silicone carbide paper. The specimens were thermocycled for 2,000 cycles between $5^{\circ}C$ and $55^{\circ}C$ distilled water. After thermocycling, bi-axial fracture strengths were measured using a compressive-tensile tester(Zwick 1456 Z020, Germany) with the cross head speed of 0.5mm/minute. The results were as follows: 1. Two factors of the kind and color of materials had a main effect on bi-axial fracture strength (p<0.01), and bi-axial fracture strength was influenced significantly by the kinds of materials (p<0.01). But there was no significant interaction between two variables of the kind and color of materials (p>0.05). 2. Comparing the mechanical properties of the materials, the elastic modulus of Z100 was higher than any other material, and there was no difference in the displacement at fracture among materials. The bi-axial fracture strength of Z100 was significantly higher than any other material, and that of resin-modified glass ionomers was significantly higher than that of conventional glass ionomer (p<0.05). 3. In the same material group, the color of material had little influence on the mechanical properties.

• Journal of The Korean Society of Clinical Toxicology
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• v.5 no.2
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• pp.112-118
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• 2007

Purpose: There have been relatively few reports of chlorophenoxy herbicide poisoning. The purpose of this study is to analyze the general characteristics and clinical aspects of the chlorophenoxy herbicide intoxicated patients in Korea. Methods: We prospectively evaluated the chlorophenoxy herbicide intoxicated patients visiting to the 38 emergency medical centers in Korea from the 1 August 2005 to the 31 July 2006. Results: 24 patients were enrolled during the study periods. Their mean age was 55.7 years old. The median amount of the chlorophenoxy herbicide intoxicated is 150 mL. The most frequent location where the patients obtained and took the chlorophenoxy herbicide was their home. Frequent compounds involving chlorophenoxy herbicide poisoning were dicamba(66.7%), MCPP(16.7%), and 2,4-D(12.5%). The most common symptom of the patients was confusion and vomiting. 16 patients(66.7%) intended to suicide. 3 patients out of 24 patients(13.0%) were died. Conclusion: There were 24 patients intoxicated by the chlorophenoxy herbicide during the study periods. The mortality rate was 13.0%. The suicidal attempts and the numbers of death involving chlorophenoxy herbicide were high in Korea.

• Clean Technology
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• v.5 no.2
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• pp.79-86
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• 1999

Mutant strain EID was developed by treating Gordona sp. CYKS1 with ethylmethanesulfone, and the desulfurization characteristics of dibenzothiophene(DBT) by mutant EID was investigated. Strain EID desulfurized DBT to 2-hydroxybiphenyl (2-HBP) by 4S pathway. Desulfurization rate of the strain EID was $4.0{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$, while that of the wild type CYKS1 was $2.6{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$. The effect of glucose concentration supplied as the carbon source on the DBT desulfurization showed that DBT desulfurization rate was enhanced as the glucose concentration increased. Maximum DBT desulfurization rate was $11.1{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$ at 2.0 mM DBT concentration. As end-products such as 2-HBP and sulfate concentrations increase, DBT desulfurization activity of the strain EID decreased. When 0.2 mM of 2-HBP was added in the medium, no growth and desulfurization activity was observed. When 0.5 g/L $Na_2SO_4$ was simultaneously supplied with DBT, DBT desulfurization rate was$1.4{\mu}mol{\cdot}L^{-1}{\cdot}h^{-1}$.

• Clean Technology
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• v.13 no.3
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• pp.195-200
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• 2007

This study investigated the flow rate changes of the heterogeneous rectangular microchannels which have different hydrophilic property on the bottom surface. The heterogeneous rectangular microchannel has three native PDMS (poly-dimethyl siloxane) surfaces which were patterned by the soft lithography. PDMS bottom surface was treated by the argon plasma and coated by the allyl alcohol (99%). The channel length was 10, 20 and 30 mm and the channel width was 100, 200 and $300\;{\mu}m$, respectively. Several external voltages were applied to make the fluid flow by the electroosmosis in the microchannel. For the same electric field strength and hydrophilicity of the bottom surface, the flow rate is almost same. This result is matched to the theoretical expectation and confirms that the experimental system is reliable. With increasing the channel width, the flow rate increased for the same hydrophilicity of the bottom surface. The flow rate of the microchannel of higher hydrophilicity was larger than that of the microchannel of lower hydrophilicity. This result implies that the hydrophilicity change of the bottom surface could be applied to control the flow rate in the microchannel.

• Journal of Life Science
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• v.25 no.2
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• pp.158-163
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• 2015

Rice embryo is more abundant than endosperms in nutrients such as proteins, lipids, and vitamin B1. In this study, we constructed p53 plasmid that could be expressed in a plant system, and investigated optimal germination conditions in a variety of media. For construction of p53 plasmid, we performed p53 amplification from pCDNA-p53, subcloned to TA cloning vector, and then reconstructed into pGEM-CaMV plant expression vector. On the other hand, we prepared a variety of imbibition buffers and complete media for efficient germination of the rice embryo. Imbibition buffers prepared with different concentrations of salt or detergent showed no significant effect on germination efficiency. We prepared further culture media, such as solid agar, liquid media, and paper towel to establish the optimal conditions. Rice embryo showed germination rates of more than 70% in the solid medium, more than 60% in the paper towel medium, but less than 25% in liquid media, although germination rate did not differ with varying concentrations of salt and sucrose in culture media. Under the optimal germination conditions, we introduced the p53 plasmid using imbibition method, and finally detected human p53 gene expression in the germinated rice embryo. This method might present a novel, practical approach for evaluating efficient gene expression utilizing imbibition method in rice embryo.