• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.513-525
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• 2018

A 3 dimensional numerical analysis for shield TBM tunnel should take into account various characteristics of the shield TBM excavation, such as gap, tail void, segment installation, and backfill injection. However, analysis method considering excavation characteristics are generally mixed with various method, resulting in concern of consistency and reliability degradation of the analytical results. In this paper, a parametric study is carried out by using actually measured ground settlement data on various methods that can be used for 3 dimensional numerical analysis of shield TBM tunneling. As a result, we have analyzed and arranged an analytical method to predict similarly the behavior of ground settlement and tunnel face pressure at the design stage. Skin plate pressure, backfill pressure and soil model have been identified as the most significant influences on the ground settlement. The grout pressure model is considered to be applicable when there is no volume loss information on the excavated ground, such as seabed tunnels, or when it is important to identify the behavior around a tunnel, such as surface settlement as well as face pressure. And it is considered that designers can use these guidelines as a base material to perform a reasonable 3 dimensional numerical analysis that reflects the ground conditions and the features of the shield TBM tunneling.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.512-519
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• 2007

The purpose of this study is to investigate the potential of a novel tissue engineering approach to regenerate intervertebral disc. In this study, thermosensitive scaffold (chitosan-Pluronic hydrogel) and nanofiber were used to replace the nucleus pulposus (NP) and annulus fibrosus of a degenerated intervertebral disc, leading to an eventual regeneration of the disc using the minimally invasive surgical procedure and organ culture. In preliminary study, disc cells were seeded into the scaffolds and cellular responses were assessed by MTT assay and scanning electron microscopy (SEM). Based on these results, we could know that tissue engineered scaffolds might provide favorable environments for the regeneration of tissues. Organ culture was performed in fresh porcine spinal motion segments with endplates on both sides. These spinal motion segments were classified into three groups: control (Intact), injured NP (Defect), and inserting tissue engineered scaffolds (Insert). The specimens were cultivated for 7 days, subsequently structural stability, cell proliferation and morphological changes were evaluated by the relaxation time, quantity of DNA, GAG and histological examination. In these results, inserting group showed higher relaxation time, reduced decrement of DNA contents, and accumulated GAG amount. Consequently, the tissue engineered scaffolds used in this study seen to be a promising base scaffolds for regenerative intervertebral disc due to its capacity to absorb external dynamic loading and the possible ideal environment provided for disc cell growing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.228-236
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• 2016

The purpose of this study was to explore the effects of transformational leadership as perceived by nurses working in medical institutions on their work attitudes using psychological capital as a mediating variable. Subjects were 201 nurses working in three general hospitals located in Seoul with more than 300 beds, and SPSS Windows 20.0 and AMOS 20.0 were used for data analysis. As the results of the analysis, transformational leadership had direct effects on psychological capital (.68, p=.007), turnover intention (-.34, p=.008), and meaning of work (.11, p=.007), whereas psychological capital had direct effects on meaning of work (.26, p=.009) and turnover intention (-.07, p=.041). In addition, transformational leadership had indirect effects on turnover intention (-.05, p=.087) and meaning of work (.18, p=.004). The results of this study can be used as a base material in the development of programs to exert positive effects on nurses' work attitudes.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1119-1127
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• 2019

This study analyzes the content of niacin, B1, and B2, which are among the water-soluble vitamin B group, in cultivars of the commonly consumed agricultural products of apples, peaches, nectarines and strawberries to compare content differences and to use results as base material for the Korean Food Composition Table. While the vitamin B1 content of apples according to different cultivars was found to be within the ranges of 0.063-0.208 mg/100g, and the content of vitamin B2 was found to be within the value ranges of 0.006-0.031 mg/100g, no niacin was found. The vitamin B1 content of peaches and nectarines according to different cultivars was found to be within the value ranges of 0.014-0.276 mg/100g, the content of vitamin B2 was found to be within he value ranges of 0.019-0.042 mg/100g, and niacin content was found to be within the value ranges of 0.298-1.096 mg/100g. The vitamin B1 content of strawberries according to cultivars was found to be within the value ranges of 0.112-0.394 mg/100g, the content of vitamin B2 was found to within the value ranges of 0.001-0.027 mg/100g, and niacin content was found to be within the value ranges of 0.388-0.809 mg/100g. Therefore, when nutrient composition analysis databases for the fruits of apples, peaches, and strawberries are constructed, cultivar factors must be put into consideration. In addition, differences can be found according to fruit harvest times, cultivation methods, and environmental factors, so related additional is needed.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1881-1891
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• 2000

Cenosphere particles of different fly ash formed at the pulverized coal power plant were hollow sphere or filled with small particles inside solid particles. And size was relatively larger than other fly ash particles as well as specific gravity was small to suspend in the water. In this paper, it was demonstrated to contain a variety of morphological particle type, and the physical and chemical properties related to the cenosphere and fly ash particles. Furthermore it was estimated the possibility to reuse the cenosphere particles on the base of cenosphere properties. Cenosphere formation resulted from melting of mineral inclusion in coal, and then gas generation inside the molten droplet. As the aluminosilicate particle was progressively heated, a molten surface layer developed around the solid core. Further heating leaded to cause the formation of fine particles at the core. The mass median diameter(MMD) of cenosphere particles was $123.11{\mu}m$ and the range of size distribution was $100{\sim}200{\mu}m$ with single modal. It was represented that specific density was $0.67g/cm^3$ fineness was $1135g/cm^3$. The chemical components of cenosphere were similar to other fly ash including $SiO_2$, $Al_2O_3$, but the amount of the chemical component was different respectively. In the case of fly ash, $SiO_2$ concentration was 54.75%, and $Al_2O_3$ concentration was 21.96%, so this two components was found in 76.71% of the total concentration. But in the case of cenosphere, it was represented that $SiO_2$ concentration was 59.17% and $Al_2O_3$ concentration was 30.16%, so this two components was found in 89.33% of the total concentration. Glassy component formed by the aluminosilicate was high in the cenosphere, so that it was suitable to use insulating heat material.

• Clean Technology
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• v.19 no.3
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• pp.313-319
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• 2013

To produce biodiesel efficiently from fish oil containing 4% free fatty acid, esterification and trans-esterification were carried out with Vietnam catfish oil, which was kindly provided from GS-bio company. Heterogeneous solid acid catalysts such as Amberlyst-15 and Amberlyst BD-20 and sulfuric acid as homogeneous acid catalyst were used for the esterification of free fatty acids in the fish oil. Sulfuric acid showed the highest removal efficiency of free fatty acid and the shortest reaction time among three acid catalysts. The base catalysts for trans-esterification such as KOH, $NaOCH_3$ and NaOH were compared with each other and KOH was determined to be the best transesterification catalyst. Some solid material, which assumed to be saponified product from glycerol and biodiesel, were observed to form in the fish oil biodiesel when using $NaOCH_3$ and NaOH as the transesterification catalyst. The initial acid value of fish oil was proven to have a negative effect on biodiesel conversion. Of the three catalysts, KOH catalyst transesterification was shown to have high content of FAME and the optimal ratio of methanol/oil ratio was identified to be 9:1.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.370-375
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• 2008

When customer makes a phone call to get the necessary information, ARS (Automatic Response System) will provide them without the limitation of time and place. Therefore, the application field of ARS (Automatic Response System) has been expanded and also occupancy rates arepretty high. However, compared with the importance of ARS, there is little study regarding the closest information structure of the actual users. Therefore, this research is about the ARS information structure of Gimhea BIS (Bus Information System), and the point of this research is to analyze the problem of the ARS information structure so we can suggest an idea to improve it. As the methods of study, drawing the workflow of ARS, conducting user observation, comparing with cases another region and analysis them. As a result, by and large there was error in the structure of information so, system reformation was required. Now that, we suggested two ideas for the improvement and we conducted usability test under that problem. Usability test was conducted by Lab test with interview. As a result, we could understand merits and demerits of two ideas for improvement, and we completed final improvement to highlight only merits of two ideas for improvement. This study will be utilized as the base material to improve ARS of Gimhea BIS.

• Journal of Environmental Science International
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• v.22 no.10
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• pp.1295-1304
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• 2013

This study was carried out to evaluate the physicochemical properties and perform a feasibility analysis of planting material composed of topsoil from river improvement and non-improvement areas. The results showed that the physicochemical properties of topsoil from river improvement areas were on the average sandy loam~loamy sand in soil texture, 5.6~6.8 in pH, 0.01~0.06 dS/m in EC, 0.9~2.1% in OM, 0.02~0.12% in T-N, 8~14 $cmol^+/kg$ in CEC, 0.01~0.08 $cmol^+/kg$ in Ex. $K^+$, 2.55~11.11 $cmol^+/kg$ in Ex. $Ca^{2+}$, 0.34~2.06 $cmol^+/kg$ in Ex. $Mg^{2+}$, and 3~396 mg/kg in Av. $P_2O_5$. And non-improvement areas showed on average sandy clay loam~sand in soil texture, 5.7~6.7 in pH, 0.02~0.08 dS/m in EC, 0.9~4.4% in OM, 0.02~0.23% in T-N, 7~18 $cmol^+/kg$ in CEC, 0.01~0.08 $cmol^+/kg$ in Ex. $K^+$, 3.81~12.67 $cmol^+/kg$ in Ex. $Ca^{2+}$, 0.60~1.95 $cmol^+/kg$ in Ex. $Mg^{2+}$, and 3~171 mg/kg in Av. $P_2O_5$. Meanwhile, the results of an applied valuation of topsoil- based planting were as follows. Ex. $K^+$ levels were low grade in all survey areas. OM was low grade in 12 improvement areas and 11 non-improvement areas. Av. $P_2O_5$ levels were low grade in 10 improvement areas and 10 non-improvement areas. T-N was low grade in six improvement areas and four non-improvement areas. Ex. $Mg^{2+}$ levels were low grade in two improvement areas.

• Culinary science and hospitality research
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• v.17 no.4
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• pp.251-262
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• 2011

The preference for maesengee sauce was investigated by developing 3 types of maesengee sauces. Through the comparative analysis of the developed maesangee sauces, the study aimed to develop maesangee sauce as a health functional food and to activate the local economy by the development of maesangee sauce as the processed food in the future. For the composition analysis of maesangee, the maesangee that was purchased from Gangjin-gun in July, 2009 was used as a base material. Based on the investigation results of preference for maesangee sauces, the following 3 types of maesangee sauces including maesangee red vinegar sauce, maesangee plain yogurt sauce and maesangee wrapping sauce were developed. By performing the comparative analysis of preference for the developed maesangee sauce types, this study aimed to put perfection in the research. The sample product of the developed maesangee sauce was used for the questionnaire survey for 42 students attending culinary colleges located in Gwangju from November 9, 2009 to November 16, 2009. For the statistical analysis, frequency analysis was used. The composition analysis result of maesangee revealed the presence of p(227.98mg/100g), Ca(58.32mg/100g) and Fe(7.8mg/100g), No detection of Vitamin A($0{\mu}gRE$/100g), Vitamin $B_1$(0.0837mg/100g), Vitamin $B_2$(0.0641mg/100g), Vitamin B6(0.0261mg/100g), Vitamin C(19.9877mg/100g), Vitamin E(0.3677mgaTF/100g), Vitamin K($7.2079{\mu}g$/100g), and Niacin(1.5057mgaNF/100g). Based upon the questionnaire survey results, the sample product development of maesangee red vinegar sauce, maesangee plain yogurt sauce and maesangee wrapping sauce was achieved along with their preparation methods.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.642-653
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• 2006

Purpose : The purpose of this study was to investigate the effect of the output energy(voltage) of laser welding on the strength and properties of joint of cast titanium(CP Gr II) and titanium alloy(Ti-6Al-4V). Material and method : Cast titanium and its alloy rods(ISO6871) were prepared and perpendicularly cut at the center of the rod. After the cut halves were fixed in a jig, and the joints welded with a laser-welding machine at several levels of output voltage of $200V{\sim}280V$. Uncut specimens served as the non-welded control specimens The pulse duration and pulse spot size employed in this study were 10ms and 1.0mm respectively. Tensile testing was conducted at a crosshead speed of 0.5mm/min. The ultimate tensile strength(MPa) was recorded, and the data (n=6) were statistically analyzed by one-way analysis of variance(ANOVA) and Scheffe's test at ${\alpha}$=0.05. The fracture surface of specimens investigated by scanning electron microscope (SEM). Vickers microhardness was measured under 500g load of 15seconds with the optimal condition of output voltage 280V. Results : The results of this study were obtained as follows, 1. When the pulse duration and spot size were fixed at 10ms and 1.0mm respectively, increasing the output energy(voltage) increased UTS values and penetration depth of laser welded to titanium and titanium alloy. 2. For the commercial titanium grade II, ultimate tensile strength(665.3MPa) of the specimens laser-welded at voltage of 280V were not statistically(p>0.05) different from the non-welded control specimens (680.2MPa). 3. For the titanium alloy(Ti-6Al-4V), ultimate tensile strength(988.3MPa) of the specimens laser-welded at voltage of 280V were statistically(p<0.05) different from the non-welded control specimens (665.0MPa). 4. The commercial titanium grade II and titanium alloy(Ti-6Al-4V) were Vickers microhardness values were increased in the fusion zone and there were no significant differences in base metal, heat-affected zone.