• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.635-642
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• 2014

In this paper, an efficient technique is developed to predict failure probability of three failure modes(case rupture, fracture and bolt breakage) related to solid rocket motor case due to the inner pressure during the mission flight. The overall procedure consists of the steps: 1) design parameters affecting the case failure are identified and their uncertainties are modelled by probability distribution, 2) combustion analysis in the interior of the case is carried out to obtain maximum expected operating pressure(MEOP), 3) stress and other structural performances are evaluated by finite element analysis(FEA), and 4) failure probabilities are calculated for the above mentioned failure modes. Axi-symmetric assumption for FEA is employed for simplification while contact between bolted joint is accounted for. Efficient procedure is developed to evaluate failure probability which consists of finding first an Most Probable Failure Point(MPP) using First-Order Reliability Method(FORM), next making a response surface model around the MPP using Latin Hypercube Sampling(LHS), and finally calculating failure probability by employing Importance Sampling.

• Fashion & Textile Research Journal
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• v.1 no.2
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• pp.173-181
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• 1999

The purpose of this study was to investigate actual sleeping environments in Ondol rooms depending on the season. The experiment was performed on five healthy women. The bedroom environments using Ondol were measured in five cases (three apartments and two houses). The environments in bedroom, bedding temperature, skin temperature and thermal sensation were measured continuously through the seven days for each season in real life. This data of sleeping environments were analyzed in the view of seasonal variations and housing types. Annual average bedroom temperatures: $26.2{\sim}31.0^{\circ}C$ in apartments, $15.7{\sim}33.6^{\circ}C$ in houses. Annual average bedroom humidity: 48.3~82.1% RH in apartments, 64.9~87.0% RH in houses. During sleeping, temperatures of contact surfaces like sheets and under quilts ranged between $30.5^{\circ}C$ and $34.1^{\circ}C$ regardless of season or housing type. Annual average rectal temperature was $36.8^{\circ}C$ with no significant difference in season or housing type. In the point of thermal sensation, neutral temperature of the bedroom was $25.9^{\circ}C$ in apartments and $20.3^{\circ}C$ in houses. It was concluded that in spite of thermal environmental variations according to the seasons, skin, bedding and bedroom temperatures in apartments were better and more stable than those of houses. It is regarded that while houses are brick structured, apartments are steel-frame structured. Due to better insulation and air tightness, apartments were affected less from outdoor temperature and maintained higher room temperature than houses.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.241-249
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• 2012

The rapid development of the current information and communication brings big changes and progress in the health service delivery system. And it is becoming the worldwide trend increasingly. As the name of medical information, by more rapid, detail and more quickly to the patients and diagnosis of the disease it provides not only a high level of health care services but also hospitals and related institutions are making increase the efficiency of the work. Among them, the Telemedicine, that system has many advantage which can expect the shorten the waiting time and the uniform high level of medical, etc. without visiting medical institutions. Especially, the most advantage is it can increase the accessibility of information about extensive medical, without regard to the time and place. But this is the reality, which compared speed the development of modern science and technology with lack of operational regulations and mindset. Current in our Medical Law, it regulates the Telemedicine, but it has Institutional, facility, and environmental constraints. Because, there is no detailed legal relationship. And it takes that in terms of a special form called by a non-face-to-face contact with medical practice rather than the scene. Therefore, in this paper will find a way out to activate the Telemedicine by presupposes the development potential is infinite and find the legal issues and improvements.

• Journal of the Mineralogical Society of Korea
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• v.20 no.2 s.52
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• pp.71-81
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• 2007

The marble-type dolomite from the Jasung Mine, which was farmed by duplicated affects of contact metamorphism and subsequent hydrothermal alteration, corresponds to a high-purity dolomite ranging up to above 98wt.% in dolomite contents. The dolomite contain minor impurities such as quartz, muscovite, and pyrite. It is characteristic that the dolomite is fairy Fe-rich corresponding to 0.4 wt.% due to the presence of pyrite of possible hydrothermal origin. The dolomite is nearly white-colored and constituting with subhedral crystals ranging $0.35{\sim}0.46mm$M in size, forming equigranular texture. Compared to the typical high-Ca limestone from the Pungchon Formation, the powder characteristics of dolomite is rather superior in milling efficiency, yields of fine particles, and size distribution. In addition, except for iron contents, the dolomite powder is no less superior than the limestone in quality and characteristics as fillers with respects to not only whiteness, oil absorption, and specific surface area but also shape characters such as elongation ratio, aspect ratio, and sphericity. This good characteristics of dolomite powder seem to be originated basically from comparatively higher grade and crystallinity of dolomite. Higher iron contents and the presence of sulfides prevents the dolomite from application for uses by thermal treatment, except for metallic manufacture. However, if proper ore separation procedure is available, the dolomite can be sufficiently utilized as substitutes for high-Ca limestone in most fields of filler industries.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.51-62
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• 2016

Parametric studies for various site conditions by using 3d numerical model were carried out in order to estimate dynamic behavior of soil-pile-structure system in dry soil deposits. Proposed model was analyzed in time domain using FLAC3D which is commercial finite difference code to properly simulate nonlinear response of soil under strong earthquake. Mohr-Coulomb criterion was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling was used as boundary condition to reduce analysis time. Also, initial shear modulus and yield depth were appropriately determined for accurate simulation of system's nonlinear behavior. Parametric study was performed by varying weight of superstructure, pile length, pile head fixity, soil relative density with proposed numerical model. From the results of parametric study, it is identified that inertial force induced by superstructure is dominant on dynamic behavior of soil-pile-structure system and effect of kinematic force induced by soil movement was relatively small. Difference in dynamic behavior according to the pile length and pile head fixity was also numerically investigated.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.284-289
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• 2003

Titanium mesoporous materials have received increasing attention as a new photocatalyst in the field for photocatalytic degradation of organic compounds. The photocatalytic degradation of chlorothalonil by mesoporous titanium oxo-phoswhate (Ti-MCM) was investigated in aqueous suspension for comparison with $TiO_2$, (Degussa, P25) using as an effective photocatalyst of organic pollutants. Mesoporous form of titanium Phosphate has been prepared by reaction of sulfuric acid and titanium isopropoxide in the presence or n-hexadecyltrimethylammonium bromide. The XRD patterns of Ti-MCM are hexagonal phases with d-spacings of 4.1 nm. Its adsorption isotherm for chlorothalonil reached at reaction equilibrium within 60 min under dark condition with 28% degradation efficiency. The degradation ratio of chlorothalonil after 9 hours under the UV radiation condition (254 nm) exhibited 100% by Ti-MCM and 88% by $TiO_2$. However, these degradation kinetics in static state showed a slow tendency compared to that of stirred state because of a low contact between titanium matrices and chlorothalonil. Also, degradation efficiency of chlorothalonil was increased with decreasing initial concentration and with increasing pH of solution. As results of this study, it was clear that mesoporous titanium oxo-phosphate with high surface area and crystallinity could be used to photo- catalytic degradation of various organic pollutants.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.239-246
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• 1999

A highly sensitive photovoltaic infrared photodiode was fabricated for detecting infrared light in $3{\sim}5\;{\mu}m$ wavelength range on InSb wafer with p-i-n structure grown by MOCVD. Silicon dioxide($SiO_2$) insulating films for the junction interface and surface of photodiode were prepared using RPCVD because InSb has low melting point and evaporation temperature. After formation of In ohmic contacts by thermal evaporation, the electrical properties of the photodiode were characterized in dark state at 77K. A product of zero-bias resistance and area($R_0A$) showed $1.56{\times}10^6\;{\Omega}{\cdot}cm^2$ that satisfied BLIP(background limited infrared photodetector) condition. When the photodiode was tested under infrared light, the normalized detectivity of about $10^{11}\;cm{\cdot}Hz^{1/2}{\cdot}W^{-1}$ was obtained. we successfully fabricated a unit cell with InSb IR array with good quantum efficiency and high detectivity.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1141-1147
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• 2006

In order to applicate a newly method for powdered activated carbon(PAC) selection based on economic efficiency, PAC adsorption tests were performed for removal of MIB and dissolved organic carbon(DOC) in drinking water supplies. The removal rate of MIB increased when the PAC dose increased. The Coal-based PACs were superior for adsorption of MIB compared to wood-based PACs. PAC adsorption of DOC and $UV_{254}$ were a little different for different PACs and types of raw water, but both were lower than adsorption of MIB. Among the tested PACs, the one called P-1000 was most effective for removal of MIB, DOC and $UV_{254}$. Most of the organics in the tested samples were proven by excitation emission matrix(EEM) results to be fulvic-like materials. Especially, fulvic-like materials, humic-like materials, and soluble microbial byproduct(SMP)-like materials decreased after contact with PAC. P-1000 which had the lowest MIB cost index(MCI) was selected as the optimum PAC for the target water. PAC efficiency and treatability, particle size and distribution, and the cost associated with PAC dosing for MIB removal according to DOC concentration should all be considered before making the final selection of the best PAC for the target water.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.47-52
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• 2009

This study has been to examine the occupational exposure levels of Fluorouracil (5-FU) in a hospital and to investigate the most effective cleaning reagent for control. Fluorouracil is one of the cytotoxic drugs which are therapeutic agents used to treat cancer. The health practitioners working in the cytotoxic work room and oncology ward areas are exposed to adverse health risks like cytogenetic and DNA damage from cytotoxic drugs exposure by frequent skin contact from contaminated surfaces. Four kinds of cleaning reagents has been examined to degrade the 5-FU. It was found that 5-FU was only degraded soon after the reaction in 0.5%(w/v) NaClO solution. Therefore, 0.5%(w/v) NaClO solution has been chosen to decompose any residues on the contamination surfaces. A substantial level of contamination was found on the surfaces of cytotoxic work room and oncology ward areas. The contamination ranges of the surfaces in cytotoxic work room and oncology ward areas were from 2.0 to $13.8{\mu}g/m^2$ and 5.39 to $11.53{\mu}g/m^2$ respectively. Consequently, regulation of the occupational exposure limit, procedure of special cleaning, and the use of personal protective equipment are recommended during the manipulation and administration of the drugs to avoid skin contamination from cytotoxic drugs like 5-FU.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.18-25
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• 2005

Characteristics of phenanthrene removal in an electrokinetic (EK)-Fenton process were investigated in a viewpoint of concentration and ionic strength of electrolytes. When three kinds of electrolytes (NaCl, $KH_2PO_4,\;and\;MgSO_4$) were used, the increase in electrolyte concentration caused the decrease of electrical potential gradient. The increase of electrical conductivity was due to the increase of ionic concentration in soil. The decrease of accumulated electroosmotic flow (EOF) with increase in electrolyte concentration was due to the decrease of zeta potential. The removal efficiency was in proportion to accumulated EOF which depended on ionic strength. Total energy expenditure without electrolyte was 10-30 times higher than its with 0.5 M electrolyte. The lower removal efficiency was caused by the lower energy expenditure with 0.5 M one. An effective EK-Fenton process was determined from considering the removal efficiency and the energy expenditure, simultaneously.