• 한국표면공학회지
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• 제18권1호
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• pp.5-11
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• 1985

Titanium was deposited onto AISI-430 stainless steel by chemical vapor deposition from $TiI_4\;and\;H_2$ gas mixture. Effects of temperature, flow rate of the gas, and $TiI_4$ partial pressure on the deposition rate were thoroughly investigated. The deposition rate of Ti was found to be constant at the given temperature and was increased with increasing temperature. The rate is controlled by surface reaction at the flow rate of gas higher than 500 ml/min, whereas at the flow rate lower than that by diffusional process. It is also interesting to note that the reaction mechanism changes at 1050$^{\circ}C$, at temperatures lower than 1050$^{\circ}C$ the activation energy is 56.9 Kcal/mol, whilst at temperatures higher than that is 8.3 Kcal/mol.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 추계학술대회논문집
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• pp.72-96
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• 1997

To investigate the difference of sweating reaction on somato types. We measured total sweat rate, locl sweat rate, skin temperature, physiological reactions and psyschological reactions at $25{\pm}1^{\circ}C$ and $25{\pm}1^{\circ}C$ under laboratory conditions. Nine healthy adult females were divided into three somato types (slender(3), normal(3) and obese type(3)). The results were as follows; Total sweat rate was highest in obese type, and then comes normal type and slender type in order. Local sweat rate was highest in infrascapular area, and then breast, the back of the hand, upperarm, ant. leg, and ant. thigh in order in all somato types. Mean skin temperature was highest in slender type, and then normal type and obese type in order. Rectal temperature, blood pressure and pulse rate were highest in boese type. Psychological reactions were appeared 'hot' 'humid' 'sweat' as ambient temperature go up. And somato types make little difference in psychological reactions.

• 대한인간공학회지
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• 제17권2호
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• pp.65-82
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• 1998

To investigate the difference of sweating reaction by the somato types, we measured total sweat rate, local sweat rate, skin temperature, physiological reaction and psychological reaction at $25{\pm}1^{\circ}C$ and $29{\pm}1^{\circ}C$ under laboratory conditons. Nine healthy adult females were divided into three somato types : slender (3), normal (3) and obese (3). The results were as follows ; Total sweat rate was highest in the obese type, followed by the normal and slender types in order. Local sweat rate was highest in the infrascapular area, and then came breast, the back of the hand, upper ann, anterior leg, and anterior thigh in all somato types. Mean skin temperature was highest in the slender type, and followed the normal and obese types. Rectal temperature, blood pressure and pulse rate were highest in the obese type. Psychological reaction appeared 'hot', 'humid', 'sweaty' as ambient temperature went up. Somato types made little difference in psychological reaction.

• 한국세라믹학회지
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• 제31권3호
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• pp.257-264
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• 1994

The objectives of this study were to develop the low pressure chemical vapor deposition(LPCVD) process of SiC and to fabricate pure and dense SiC layer onto graphite substrate at low temperature. The deposition experiments were performed using the MTS-H2 system (30 torr) in the deposition temperature ranging from 100$0^{\circ}C$ to 120$0^{\circ}C$. The deposition rate of SiC was increased with the temperature. The rate controlling step can be classified from calculated results of the apparent thermal activation energy as follows; surface reaction below 110$0^{\circ}C$ and gas phase diffusion through a stagnant layer over 110$0^{\circ}C$. The deposited layer was $\beta$-SiC with a preferred orientation of (111) and the strongly faceted SiC deposits were observed over 115$0^{\circ}C$.

• 생명과학회지
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• 제24권3호
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• pp.318-322
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• 2014

Chlamydophila pneumonia는 전 세계적으로 지역사회 폐렴을 유발하는 중요한 원인체이며 청소년과 젊은 성인에서는 경미한 폐렴 및 기관지염을 유발하나 면역력인 약한 소아나 기저 질환이 있는 노인층에서는 치명적인 질환을 일으킬 수 있다. 현재까지 국내에서 집단생활과 연관된 감염률에 대한 연구가 없는 실정이다. 본 연구에서는 미세면역형광법을 이용하여 대학 기숙사 거주자의 거주 기간에 따른 감염률을 조사하였다. C. pneumonia 과거 감염은 IgG 항체 역가 1:32 이상으로 하였다. 현재 감염은 IgG 항체 역가가 1:512 이상이거나, IgM 항체 역가가 1:16 이상이면서 류마토이드 인자 음성인 경우를 현재 감염으로 하였다. C. pneumonia 과거 감염률은 71.1%였으며, IgG와 IgM 항체를 이용한 현재 감염률은 각각 28.3%와 23.3%를 나타냈다. C. pneumoniae IgG 항체에 의한 과거 감염률은 집단생활이 1개월, 7개월, 13개월, 35개월 군에서 각각 50%, 71.4%, 66.7%, 89.5%로 나타났다. IgG 항체에 의한 현재 감염률은 1개월, 7개월, 13개월, 35개월 군에서 각각 50%, 28.6%, 33.3%, 10.5%를 보였으며 IgM 항체를 이용한 조사에서는 각각 41.7%, 28.6%, 26.7%, 5.3%를 나타냈다. 이상의 결과로 볼 때 집단생활자의 경우 C. pneumoniae 과거감염은 집단생활 경험의 개월 수가 많을수록 증가하였으며, 현재 감염율은 집단생활 초기에 증가하였다가 개월 수가 증가할수록 감소하였다. 본 연구는 C. pneumoniae의 집단시설 내의 혈청역학적 조사 및 예방법 연구에 있어 중요한 자료가 될 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4571-4584
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• 2022

The analysis of rapid flow transients in Reactor Coolant Pumps (RCP) is essential for a reactor safety study. An accurate and precise analysis of the RCP coastdown is necessary for the reactor design. The coastdown of RCP affects the coolant temperature and the colloidal crud in the primary coolant. A realistic and kinetic model has been used to investigate the behavior of activated colloidal crud in the primary coolant and steam generator that solves the pump speed analytically. The analytic solution of the non-dimensional flow rate has been determined by the energy ratio β. The kinetic energy of the coolant fluid and the kinetic energy stored in the rotating parts of a pump are two essential parameters in the form of β. Under normal operation, the pump's speed and moment of inertia are constant. However, in a coastdown situation, kinetic damping in the interval has been implemented. A dynamic model ACCP-SMART has been developed for System Integrated Modular and Advanced Reactor (SMART) to investigate the corrosion due to activated colloidal crud. The Fickian diffusion model has been implemented as the reference corrosion model for the constituent component of the primary loop of the SMART reactor. The activated colloidal crud activity in the primary coolant and steam generator of the SMART reactor has been studied for different equilibrium corrosion rates, linear increase in corrosion rate, and dynamic RCP coastdown situation energy ratio b. The coolant specific activity of SMART reactor equilibrium corrosion (4.0 mg s^-1) has been found 9.63×10^-3 µCi cm^-3, 3.53×10^-3 µC cm^-3, 2.39×10^-2 µC cm^-3, 8.10×10^-3 µC cm^-3, 6.77× 10^-3 µC cm^-3, 4.95×10^-4 µC cm^-3, 1.19×10^-3 µC cm^-3, and 7.87×10^-4 µC cm^-3 for ²⁴Na, ⁵⁴Mn, ⁵⁶Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁹Mo, and ⁵¹Cr which are 14.95%, 5.48%, 37.08%, 12.57%, 10.51%, 0.77%, 18.50%, and 0.12% respectively. For linear and exponential coastdown with a constant corrosion rate, the total coolant and steam generator activity approaches a higher saturation value than the normal values. The coolant and steam generator activity changes considerably with kinetic corrosion rate, equilibrium corrosion, growth of corrosion rate (ΔC/Δt), and RCP coastdown situations. The effect of the RCP coastdown on the specific activity of the steam generators is smeared by linearly rising corrosion rates, equilibrium corrosion, and rapid coasting down of the RCP. However, the time taken to reach the saturation activity is also influenced by the slope of corrosion rate, coastdown situation, equilibrium corrosion rate, and energy ratio β.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.960-964
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• 2004

[ $Ba_2NaNb_5O_{15}$ ](BNN) thin films have been prepared by the ion beam sputter deposition (IBSD) method on Pt coated Si substrate at temperature as low as $600^{\circ}C$ XRD, SEM were used to investigate the crystallization and microstructure of the films. It was found that the films were crack-free and uniform in microstructure. The electric properties of thin films were carried out by observation of D-E hysteresis loop, dielectric constant and leakage current. It was found the deposition rate strongly influenced the phase formation of the films, where the phase of $BaNb_2O_6$ was always formed when the deposition rate was high. However, the single phase (tungsten bronze structure ) BNN thin film was obtained with the deposition rate as low as $22{\AA}/min$. The remanent polarization Pr and dielectric constant are about 1-2 ${\mu}C/cm^2$ and $100\sim200$, respectively. It was also founded the electric properties of thin films were influenced by the deposition rate. The Pr and dielectric constant of films increased with the decrease of deposition rate. The effects of annealing temperature and annealing time to the crystallization behavior of films were studied. The crystallization of thin film started at about $600^{\circ}C$. The adequate crystallization was gotten at the temperature of $650^{\circ}C$ when the annealing time is 0.5 hour or at the temperature of $600^{\circ}C$ when the annealing time is long as 6 hours.

• 음성과학
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• 제10권3호
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• pp.241-250
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• 2003

In this paper, we implemented the vocoder of variable rate by applying the SOLA-B algorithm to the G.729A to the TMS320C5416 in real-time. This method using the SOLA-B algorithm is that it is reduced the duration of the speech in encoding and is played at the speed of normal by extending the duration of the speech in decoding. But the method applied to the existed G.729A and SOLA-B algorithm is caused the loss of speech quality in G.729A which is not reflected about length variation of speech. Therefore the proposed method is encoded according as it is modified the structure of LSP quantization table about the length of speech is reduced by using the SOLA-B algorithm. The vocoder of variable rate by applying the G.729A and SOLA-B algorithm is represented the maximum complexity of 10.2MIPS about encoder and 2.8MIPS about decoder in 8kbps transmission rate. Also it is evaluated 17.3MIPS about encoder, 9.9MIPS about decoder in 6kbps and 18.5MIPS about encoder, 11.1MIPS about decoder in 4kbps according to the transmission rate. The used memory is about program ROM 9.7kwords, table ROM 4.69kwords, RAM 5.2kwords. The waveform of output is showed by the result of C simulator and Bit Exact. Also, the result of MOS test for evaluation of speech quality of the vocoder of variable rate which is implemented in real-time, it is estimated about 3.68 in 4kbps.

• Clinical and Experimental Reproductive Medicine
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• 제17권2호
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• pp.167-172
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• 1990

This study was carried out to clarify the effects of various kinds of cryoprotectants which were frequently used in freezing embryos of domestic animals on the survival of frozen-thawed mouse embryos. Mouse embryos were collected by hyperstimulation induction of ICR mouse. The samples were slowly cooled ($l^{\circ}C/min$) to temperatures between $-7^{\circ}C$ and $-30^{circ}C$ before direct transfer to liquid nitrogen ($-196^{\circ}C$) and thawed rapidly ($-500^{\circ}C$/min). As cryoprotectants, Glycerol, DMSO, Ethylene glycol and Propylene glycol were used and applied each 2 cell, 8 cell, morula in embryo stage. After normal mouse embryos developed to blastocyst by in vitro culture, we observed recovery rate and developing rate of embryos at thawing. The results obtained in these experiments were as follows : 1. The in vitro development rate from the frozen-thawed 2 cell embryos to the blastocyst were 67.7% in ethylene glycol, 65.7% in Propylene glycol, 55.2% in glycerol and 50.0% in DMSO respectively. 2. The in vitro development rate from the frozen-thawed 8 cell embryos to the blastocyst were 83.6% in DMSO, 75.7% in glycerol, 52.2% in propylene glycol respectively. 3. The in vitro development rate from the frozen-thawed morula to the blastocyst were 84.2% in glycerol, 80.0% in DMSO, 66.6% in propylene glycol and 55.2% in ethylene glycol respectively.

• 한국재료학회지
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• 제22권10호
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• pp.513-518
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• 2012

Recently, automobile parts have been required to have high strength and toughness to allow for weight lightening or improved stability. But, traditional micro-alloyed steel cannot be applied in automobile parts. In this study, we considered the influence of quenching temperature and cooling rate for specimens fabricated by vacuum induction furnace. Directly quenched micro-alloyed steel for hot forging can be controlled according to its micro structure and the heat-treatment process. Low carbon steel, as well as alloying elements for improvement of strength and toughness, was used to obtain optimized conditions. After hot forging at $1,200^{\circ}C$, the ideal mechanical properties (tensile strength ${\geq}$ 1,000 MPa, Charpy impact value ${\geq}\;100\;J/cm^2$) can be achieved by using optimized conditions (quenching temperature : 925 to $1,050^{\circ}C$, cooling rate : ${\geq}\;5^{\circ}C/sec$). The difference of impact value according to cooling rate can be influenced by the microstructure. A fine lath martensite micro structure is formed at a cooling rate of over $5^{\circ}C/sec$. On the other hand, the second phase of the M-A constituent microstructure is the cause of crack initiation under the cooling rate of $5^{\circ}C/sec$.