• Advances in pediatric surgery
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• v.7 no.2
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• pp.105-111
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• 2001

To investigate the diagnostic accuracy and applicability of barium enema(BE) and rectal suction biopsy with acetyl cholinesterase(AChE) histochemistry in the diagnosis of neonatal Hirschsprung's disease(HD), we retrospectively reviewed the findings of BE and AChE staining in 96 neonates with suspected HD during a 10-year period from January 1991 to December 2000. Sixty-nine cases of HD(58 males and 11 females) and 27 cases of non-HD are included in this study. In regard to BE, HD was based on definite transitional zone, suspicious HD on reversed rectosigmoid index(RSI <1), and non-HD on normal RSI(RSI>1). The histochemical criterion used for the diagnosis of HD was that of Chow et al(1977), i.e., the presence of many coarse discrete cholinergic nerve fibers in the muscularis mucosae and in the immediately subjacent submucosa regardless of infiltration of cholinergic nerve fibers in the lamina propria. Of 66 neonates with HD who underwent BE, transitional zone was identified in 33 cases(50 %) and reversed RSI in 19 cases(21 %), microcolon in 4 cases and normal finding in 10 cases(15 %) while of 27 neonates with non-HD, there was normal finding in 16 cases and reversed RSI in 9 cases(41 %). Thus diagnostic accuracy based on transitional zone was 64 %. The positive predictive value of reversed RSI for the diagnosis of HD was 68 %. Of 42 neonates with HD who underwent AChE histochemistry, there were 41 AChE-positive reactions and one AChE-negative reaction in a neonate with total colonic aganglionosis, while of 27 cases of non-HD, there were one equivocal AChE-positive reaction and 26 AChE-negative reactions. Thus AChE histochemical study showed a 97 % diagnostic accuracy with a 98 % sensitivity and a 96 % specificity. In conclusion, we believe that BE is valuable as a first diagnostic step since about 80 % of neonates with HD show significant radiologic findings such as a transitional zone or reversed RSI. AChE histochemical study was a more reliable diagnos tic tool showing a 97 % diagnostic accuracy, and is part.

• Journal of Fashion Business
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• v.4 no.3
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• pp.1-13
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• 2000

This research chose three kinds of sleeping bags with different fillings (A: interfill polyester, B: brushed polyester, C: down) and put them in two environmental conditions (Env. I : $25{\pm}1^{\circ}C$, $50{\pm}10%$; Env. II : $18{\pm}1^{\circ}C$, $70{\pm}10%$). The measured Skin temperature, Temperature and Humidity in sleeping bag, Rectal temperature and Psychological reaction. The results of experiment were as follows: 1. The mean skin temperature of Sleeping Bag B was the closest to the most comfortable value in the two environmental conditions. 2. Temperature and humidity in sleeping bags, in both environmental conditions, contained the value nearest to the most comfortable one in Sleeping Bag B. 3. Rectal temperature in both environments had a slight change in the range of antibody temperature in all the subjects of sleeping bags. 4. As subjective psychological reaction, both thermal and humid sensation approached the most comfortable zone in Sleeping Bag B.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.47-56
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• 1996

The purpose of this study is to develope an insert metal which can be brazed at lower temperature than the conventionally used insert metal and provide higher strength joint than base metal. In the review of binary phase diagram concerning Ti, Cu and Ni resulted in the discovery of Si having eutectic composition with them. The microstructure and the distribution of elements in reaction zone between CP Ti and insert metal were investigated by Optical Microscopy, SEM/EDX, EPMA, X-RAY. The newly developed insert metal is Ti-15wt%Cu-18wt%Ni-2wt%Si, which can yield the lower brazing temperature(1183K) compared with the conventional Ti-Cu-Ni system insert metal. The joints with this insert metal had tensile strength of 385MPa in the bonding temperature range of 1183K to 1243K.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.128-135
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• 1997

Reaction diffusion and formation of $Ni_3Al$phase with $L1_2$ structure have been studied in temperature range of 1432K to 1573K using the diffusion couple of (Ni-40, 5at%Al)/(Ni-14, 1at%Al) and (Ni-49, 2at%Al)/ (Nickel). The layer growth of Ni$_{3}$Al pyhase in the annealed diffusion couple was measured by optical microscope and electron probe microanalyzer (EPMA). The layer growth of $Ni_3Al$phase in diffusion zone obeyed the parabolic law without any indication of grain boundary effects. The layer growth of $Ni_3Al$phase in temperature range of 1423K to 1573K was mainly controlled by the volume diffusion mechanism. The rate of layer growth of $Ni_3Al$phase was found to be colsely related to the composition of intermetallic compound NiAl phase. The activation energy for layer growth of $Ni_3Al$phase was calculated to be 127kJ/mol.

• Journal of the Korean Society of Visualization
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• v.11 no.1
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• pp.22-27
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• 2013

An investigation into the influence of ultrasonic standing wave on the structural behavior of propane/air premixed flame has been made to get a clue to the combustion reaction acceleration and combustion instability. Visualization technique utilizing the Schlieren photography was employed for the observation of structural variation of the flame reaction zone. Evolutionary characteristics of the flame front were caught by the high-speed Schlieren image, through which local flame velocity of the moving front were analyzed in detail.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.479-485
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• 1996

Volatile organic compounds are air pollutants exhausting from industrial process, evaporation of solvent, and so on. Most of VOCs are the combustible gas of low calorific value as it is diluted by air. The systems burning such a hazardous gas need to increase enthalpy in order to increase flame stability. In this study an incinerator with reciprocating flow in the honeycomb ceramic has been used for the experiment of VOCs control. By the reciprocating flow system, the enthalpy of combustion gas is effectively regenerated into the enthalpy increases of the combustible gas through the honeycomb ceramic, which provides a heat storage. The position of the reaction zone is strongly dependent on the parameters of mixture velocity and time frequency. Flame front is changed to the point where burning velocity is coincided with burning velocity in the honeycomb ceramic. In this system it is important that flame front should be located symmetrically at the center of honeycomb ceramic for the purpose of increasing the reaction rate at one point. Peak temperature becomes higher with decreasing time frequency, at which the flow direction is regularly reversed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.472-475
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• 2010

Theoretical consideration on the combustion behavior of nano-aluminum and water mixture was conducted. The regions are divided into; 1)water+aluminum 2)steam+aluminum 3)reaction zone. Latent heat of vaporization was considered as a function of pressure in case of phase change of water. Also, pressure exponent was studied of various sized nano particles within the range of 0.1MPa ~ 10MPa.

• Korean Membrane Journal
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• v.6 no.1
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• pp.10-15
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• 2004

We developed a water-selective ceramic composite membrane for use as a dehydration membrane reactor for dimethylether (DME) synthesis from methanol. The membranes were modified on the porous stainless steel support by the sol-gel method accompanied by a suction process. The improved membrane modification process was effective in increasing the vapour permselectivity by removal of defects and pinholes. The optimized alumina/silica composite membrane exhibited a water permeance of 1.14${\times}$10$^{-7}$ mol/$m^2$.sec.Pa and a water/methanol selectivity of 8.4 at permeation temperature of 25$0^{\circ}C$. The catalytic reaction for DME synthesis from methanol using the membrane was performed at 23$0^{\circ}C$, and the reaction conversion was compared with that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor was much higher than that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor and the conventional fixed-bed reactor was 82.5 and 68.0%, respectively. This improvement of reaction efficiency can last if the water vapour produced in the reaction zone is removed continuously.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.16-23
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• 2004

A membrane reactor concept, which combines the typical characteristics of chemical reaction with separation process, has been analyzed and simulated in this study. The advantages of the use of a membrane reactor include chemical equilibrium shift towards higher reactant conversion and purer product than the traditional reactors. A membrane reactor model which incorporates a catalytic reaction zone and a separation membrane is proposed. The water-gas shift reaction to produce hydrogen was chosen as a model reaction to be investigated. The membrane reactor is divided into smaller parts by number of n and each part (named cell), which contains both reaction and product separation function is modeled. One of the membrane outlet streams is connected to the next cell, which is repeated up to the last cell. The simulation results can be used for various purposes including decision of optimum operating condition and membrane reactor design.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.87-89
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• 2014

Spherically expanding flames are used to measure flame speeds, which are derived the corresponding laminar flame speeds at zero stretch. Flame speeds of n-butanol at high pressure are studied over an extensive range of equivalence ratios. The classical shadowgraph technique is used to detect the reaction zone. In analytical methodology the optimization process using least mean squares is performed to extract the laminar flame speeds. Laminar flame speeds are compared with results obtained from numerical work.