• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.97-105
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• 1999

In the binary system of SiC and carbon, porosity and pore size distribution of green body was controlled by varying pH, by the addition of polyelectrolyte dispersants, and by using different particle size of starting powders. The preforms having different green microstructure were fabricated by slip casting from suspensions having different dispersion condition. The reaction bonding process was carried out for these preforms. The condition of reaction bonding was 1600$^{\circ}C$ and 20 min. under vacuum atmosphere. The analyses of optical and SEM were studied to investigate the effect of green microstructure on that of reaction bonded silicon carbide and subsequently the mechanical properties of sintered body was investigated. Different green microstructures were obtained from suspensions having different dispersion condition. It was found that the pore size could be remarkably reduced for a fine SiC(0.5$\mu\textrm{m}$). The bimodal microstructure was not found in the present study, which is frequently observed in the typical reaction bonded silicon carbide. It is considered that the ratio between SiC and C was responsible for the formation of bimodal microstructure. For the preform fabricated from the well dispersed suspension, the 3-point bending strength of reaction-bonded silicon carbide was 310${\pm}$40 MPa compared to the specimen fabricated from relatively agglomerated particles having lower value 260${\pm}$MPa.

• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.407-414
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• 2006

This study was carried out to investigate soil properties, ordination, and vegetation of a forest wetland in Jangdo, Sinan-Gun. Peculiar species such as Epilobium pyrricholophum and Lycopus ramosissim us were found in the forest wetland of Jangdo, and Hosta yingeri and Carpinus turczaninovii for coreana that are an endemic species of Korea were also found. The vascular plants of 40 families 62 genera 57 species 9 varieties 1 form, total 67 taxa were accounted for. The communities were classified as Salix koreensis-Isachne globosa community, Isachne globosa community, and Miscathus sinensis var purpurascens community. Soil organic matter, total nitrogen, available phosphorous concentrations, and cation exchange capacity each ranged from 20.6 to 72.4%, 0.74 to 2.13%, 33.3 to 114.6 ppm, and 25.5 to 94.3 me/100g, respectively. Soil pH ranged from 5.10 to 5.42. Soil texture was clay loam. Results of the correlation between Jangdo forest community and environmental factor are as follows; Soil pH was the most effective factor for plant community distribution. The Salix koreensis-Isachne globosa community was found where it had the highest soil organic matter, nitrogen, and exchangeable Na, Ca, Mg concentration, ana CEC among the three communities. Miscathus sinensis var. purpurascens community was found where it had the lowest soil organic matter, nitrogen, and exchangeable Na, Ca, Mg concentration, and CEC among the three plant communities.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.76-76
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• 1993

Endotracheal intubation is common technique for general anesthesia or patency of airway. However, laryngeal intubation granuloma is the most common sequale of endotracheal intubation in otolaryngologic field. From 1982 to 1992, the authors had experienced 16 cases intubation granuloma. The following results were as follows; 1. Age distribution was mostly in the 20 to 49 years old group (84 %).The sex ratio of male to female was 1:7, predominantly in female. 2. Main sx. were hoarse in 12(75%), F.B. sensation in 3(18%), dyspnea in 1 (6%). 3. The side of lesion was bilateral in 6 cases (37%) and unilateral in 10 cases (63%). Unilateral had the 3 cases (30%) in left and the 7 cases (70%) in right. The location of mass was vocal process of arytenoid cartilage in 8 cases(50%), post 1/3 of vocal cord in 6 cases (37 %) and middle 1/3 of vocal cord in 2 cases (12 %). 4. The duration between extubation and onset of symptom in less than a month was most frequent in 7 cases (44 %) out of 16 cases. 5. The most common operation was cesarean section in 6 cases (37 %). 6. Mean duration of intubation time was 2 hour 5 minutes. 7. Composition of used intubation tube was red rubber tube. 8. One case (6 %) was recurred.

• Water for future
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• v.27 no.3
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• pp.71-82
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• 1994

A statistical characteristics, relations of calendar and water year, and frequencies of precipitaion which are necessary for water resources planning were analyzed with long historical data(1905-1991 years). And the analysis of precipitation of the drought periods in 1967-1968 years was carried out. The study basins are the five major rivers in Korea. As a results of this study, annual precipitation shows an increasing trend but its variation has no statistical significance. The rellations of calendar and water year precipitation is presented, it shows that there are little difference of the total precipitation between them. The annual minimum series of total precipitation for the periods of 3, 6, 9, and 12 months by water year are constructed, and frequency precipitation for each periods using 2-parameter lognormal distribution is presented. The analysis of the precipitation in 1967-1968 years shows in a natural river basins that it would be a moderate drought, if dry seasons(Oct-May) or wet seasons(Jun-Sep) has 75 percents of historical mean precipitation of the same periods. And if it has less than 60 percents of historical mean precipitation, it would be a severe drought.

• Journal of the Korean GEO-environmental Society
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• v.21 no.7
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• pp.17-26
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• 2020

The soft ground in the southwest coastal area composed of marine clay is greatly influenced by sediment composition, particle size distribution, particle shape, adsorption ions and pore water characteristics, tide and temperature. In addition, the geotechnical properties are very complex due to stress history, change in pore water, dissolution process and gas formation. In this study, the physical and mechanical properties of the soft ground were evaluated through field tests and laboratory tests to investigate the strength increase characteristics according to consolidation on the soft ground in the southwest coast. In addition, in order to understand the consolidation behavior of soft ground such as subsidence, pore water pressure, horizontal displacement of soil by embankment load, measuring instruments such as pore water pressuremeter, settlement gauge, inclinometer and differential settlement gauge was installed, and a piezocon penetration test was carried out step by step to confirm the increase in shear strength of the ground. Through this, it was confirmed that the shear strength of the ground is increased according to the stages of filling. In addition, by evaluating the properties of consolidation behavior, strength increase and consolidation prediction by empirical methods and theories were compared to analyze the characteristics of strength increase rate and consolidation behavior in consideration of regional characteristics.

• The Korean Journal of Petroleum Geology
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• v.10 no.1_2 s.11
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• pp.18-22
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• 2004

To identify and interpret the distribution and the characteristics of the gas hydrate layers in the Ulleung Basin, we have surveyed and gathered the multi-channel seismic data, Chirp sub-bottom profiler, SeaBeam and 12 m piston core samples since 1996. In previous works, high-resolution seismic profiles showed acoustic anomalies such as acoustic void, acoustic turbidity and pock mark which indicate the presence of gas-charged sediments. The patterns of horizontal degassing cracks originated from free methane expansion is the strong indicator of shallow gas-charged sediments in the core samples. The observation of submarine slides and slumps from destabilizing the sediments in the southern part of the Ulleung Basin may also point out that the gas had been released from gas hydrate dissociation during lowstand of sea level. The multi-channel seismic data show BSR, blanking and phase reversal. The gas hydrate layers above which large-scale shallow gases are distributed exist at the depth of about 200 m from the sea-floor with water depth of 2,100 m. From the interpretation of seismic sections in the southern Ulleung Basin, gas hydrate layers occur in the Pleistocene-Holocene sediments. These gas-charged sediments, acoustic anomalies and BSR may be all related to the existence of gas hydrate layers in the study area.

• Journal of Korean Philosophical Society
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• v.141
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• pp.133-166
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• 2017

The main aim of this paper is to show why justice is based on convention, not nature, in David Hume. Most philosopher, since Aristotle, have considered justice in relation to distribution. This understanding of justice continues up to modern times, and is handled especially in relation to ownership or private property in modern times. In modern times, private property is regarded as an absolute right that should not be violated in any case. Hume identifies this private property with justice. The absolute inviolability of private property is equivalent to never violate to justice. Hume is concerned with the question of where this justice originate. In other words, Hume is not concerned with the Kantian justification of justice, but rather with the psychological discussion of the genesis process of the idea of justice. Hume's answer is that "social utility" is its origin. Public societies are necessary conditions for human being. In other words, if public societies do not exist, humans can not exist. How then can a public society, which is a prerequisite for human being, exist or can be maintained? According to Hume, it is maintained by means of justice. So where is the ground for justice? Hume argues that the basis of justice is not nature, but human conventions. Man accepts justice tacitly and by doing so man can maintains his being. This is a rough insight of Hume. Hume uses a wide variety of concepts to carry out his argument. In this paper, we focus on how the idea of justice in human mind, based on these various concepts presented by Hume, is formed.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.76-89
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• 2018

The distribution of the combined heat and power system is active as a solution to the instability of energy supply and environmental pollution caused by continuous industrial development. In Korea, the safety standards for combined heat and power system using a gas engine are insufficient therefore the study on this is needed. In this study, the safety performance and structural/material assessment items of domestic and international standards applied to the combined heat and power system were analyzed to carry out a standardization study on safety performance applicable to 20 kW gas engine combined heat and power system. In addition, the safety performance assessment (plan) of the gas engine combined heat and power system was derived by performing risk analysis and risk assessment using HAZOP. Assessment items include engine ignition systems related to safety performance, piping tight performance, watering and temperature rise performance, combustion performance, electrical efficiency, thermal efficiency, overall efficiency and humidity performance. Gas and water pipes, gas control and shut-off valves, durability, heat resistance, and cold resistance of metal or non-metallic materials related to the structure and materials of the gas engine combined heat and power systems.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.939-944
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• 2018

Clean fire extinguishing agents refer to chemical that can replace Halon 1211 and Halon 1310 according to the Montreal Protocol fermented to protect the Earth's ozone layer. In Korea and abroad, system standardization and performance evaluation of clean fire extinguishing agents are being carried out. This paper proposes an optimal nozzle shape by modeling and numerical analysis of various nozzle shapes based on general clean fire extinguishing system. The ejection speed of the nozzle can be improved by studying three - dimensional modeling of the nozzle for two shapes, Type A and B. Flow analysis was performed on the two types of nozzles and the gas velocity and pressure distribution were measured with different nozzle diameters. It was confirmed that the jetting speed was changed at the nozzle outlet according to the number and diameter of the nozzle holes. The flow rate increased with increasing the pressure regardless of the nozzle hole diameter. Based on the results obtained from the experiment, the K-factor value was deduced. Finally, a nozzle with a 12-hole structure with a 5-mm nozzle hole was proposed.

• Journal of Korea Entertainment Industry Association
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• v.14 no.8
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• pp.337-344
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• 2020

The purpose of this study was to investigate the effect of theratainment low extremity complex exercise using unstable surface on knee and static plantar pressure in patient with genu varum. 25 adult subjects were recruited and randomized into stable surface exercise group(SEG) and unstable surface exercise group(UEG). Subjects carried out complex exercise(elastic band exercise & squat exercise) for 40 minutes, 4 times per week for 5 weeks. The knee joint distance and Q-angle of all subjects measured, the foot pressure measured distribution on the front and rear of both foots during pre and post. The most outcome at post was significantly improved than the pre outcome in the both group(p<.05). The result of this study show that the low extremity complex exercise using unstable surface may be appropriate for improving structure of knee joint and static plantar pressure in patient with genu varum. This will enable the application of low extremity complex exercise using unstable surface in rehabilitation therapy of genu varum and it will help guide the selection of the therapist as one therapeutic basis.