• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.54-60
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• 2008

Sound absorption coefficients of oak (Quercus mongolica) wood and oak mushroom bed log were measured by the two microphone transfer function method and anatomical features of oak mushroom bed log examined by stereo scope and SEM observations. The sound absorption coefficients of oak mushroom bed log seemed to be higher than those of normal oak wood specimen over all estimated frequency range. Especially, in the frequency range of 2 to 6 kHz, they were about 2~3 times higher than those of normal wood specimen. Due to fungi degradation, the specific gravity of oak mushroom bed log decreased about 70% than that of normal wood. For oak mushroom bed log, abundant pores occurred on the radial, tangential and cross sectional surface and it was considered that the pores behaved as a sound absorbing pore.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.7-13
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• 2007

A Dish type solar concentrating system consists of a parabolic concentrator and a cavity receiver. In order to achieve high temperatures from solar energy, it is essential to efficiently reflect the solar rays in the concentrator and to minimize thermal losses in the cavity receiver. Improving the economical efficiency of a solar power system required the stirling unit to be operated continuously. For continuous operation of the stilting unit, the receiver must be continuously provided with thermal energy from solar as well as additional combustion heat. It is possible for a hybrid solar receiver system equipped with an additional combustion to be operated 24 hrs/day. A hybrid solar receiver was designed and manufactured for a total thermal load of 35 kW in the operating temperature range $700^{\circ}C$ to $800^{\circ}C$. The hybrid receiver system was tested in gas-only mode by gas-fired heat to investigate thermal characteristics at inclination angle varying from 0 deg to 30 deg(cavity facing down) and the aperture to cavity diameter ratios of 0(closed cavity) and 1.0(open cavity). This paper has been conducted to measure temperature distribution in cavity surface and to analyze thermal resistances, and the evaporation and condensation heat transfer coefficient in all cases(open and closed cavity).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6C
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• pp.751-762
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• 2004

In this paper, we propose the method to derive new GRM(Generalized Reed-Muller) coefficients for each 2$^n$ polarities using Triangle cell. As the existing methods to generate GRM coefficients, there are Green's method to operate transform matrix with a given RM coefficient and Besslich's method to get other polarities using basic transfer matrices repeatedly. In this paper, Triangle cell is defined so as to obtain GRM coefficients efficiently. After arranging 2$^n$ given RM coefficients of a first row of Triangle cell, sequence modulo sum is peformed in parallel to low column by a fixed numerical formula. To prove the efficiency of proposed arithmetic method, it is compared with Besslich’s method. As the compared result, to calculate GRM coefficients of all polarities to n input variables, Besslich’s method needs 2$^n$$^{-1}$ ${\times}$(2$^n$-1) two-input Ex-ORs and the proposed method needs 2${\times}$(the number of Ex-ORs for n-1 variables)+3$^n$$^{-1}$ for the same system complexity - (lo $g_2$$^n$) $T_{X}$./.

• Structural Engineering and Mechanics
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• v.32 no.3
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• pp.429-445
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• 2009

Thermal stability of quasi-isotropic composite and polymeric structures is considered one of the most important criteria in predicting life span of building structures. The outdoor applications of these structures have raised some legitimate concerns about their durability including moisture resistance and thermal stability. Exposure of such quasi-isotropic composite/polymeric structures to various and severe climatic conditions such as heat flux and frigid climate would change the material behavior and thermal viability and may lead to the degradation of material properties and building durability. This paper presents an analytical model for the generalized problem. This model accommodates the non-linearity and the non-homogeneity of the internal heat generated within the structure and the changes, modification to the material constants, and the structural size. The paper also investigates the effect of the incorporation of the temperature and/or material constant sensitive internal heat generation with four encountered climatic conditions on thermal stability of infinite cylindrical quasi-isotropic composite/polymeric structures. This can eventually result in the failure of such structures. Detailed critical analyses for four case studies which consider the population of the internal heat generation, cylindrical size, material constants, and four different climatic conditions are carried out. For each case of the proposed boundary conditions, the critical thermal stability parameter is determined. The results of this paper indicate that the thermal stability parameter is critically dependent on the cylinder size, material constants/selection, the convective heat transfer coefficient, subjected heat flux and other constants accrued from the structure environment.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.326-332
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• 2011

Radial variation of sound absorption capability and air permeability of yellow poplar (Liriodendron tulipifera) wood in cross sectional surface and effect of steam explosion treatment were estimated by the two microphone transfer function method and the capillary flow porometry, respectively. The sound absorption coefficients of steam explosion treated wood was higher than those of control wood and these values increased with frequency. Abundant and big vessel may behave as sound absorbing pore observed on the cross sectional surface of yellow poplar wood. The sound absorption coefficients and air permeability of sapwood were higher than those of heartwood for Liriodendron tulipifera.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.267-267
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• 2012

최근 국내 반도체 장비 업체들에 의해서 차세대 반도체용 450 mm 웨이퍼 공정용 장비 개발이 진행 중에 있다. 반도체 산업은 계속해서 반도체 칩의 크기를 작게 하고, 웨이퍼 크기를 늘리면서 웨이퍼 당 칩수를 증가시켜 생산성을 향상해오고 있다. 현재 300 mm 웨이퍼에서 450 mm 웨이퍼를 도입하게 되면, 생산성 뿐만 아니라 30%의 비용절감과 50%의 cycle-time 단축이 기대되고 있다. 장비에 대한 이해와 공정에 대한 해석 능력을 위해 비용과 시간이 많이 들기 때문에 최근 컴퓨터를 활용한 수치 모델링이 진행되고 있다. 또한, 수치 모델링은 실험 결과와의 비교가 필수적이다. 본 연구에서는 450 mm 웨이퍼 공정용 장비의 전자밀도를 cut off probe를 통해 100 mTorr에 서 Ar 플라즈마를 파워에 따라 측정했다. 13.56 MHz 200 W, 500 W, 1,000 W로 입력 파워가 증가하면서 웨이퍼 중심에서 $6.0{\times}10^9#/cm^3$, $1.35{\times}10^{10}#/cm^3$, $2.4{\times}10^{10}#/cm^3$로 증가했다. 450 mm 웨이퍼 영역에서 전자 밀도의 불균일도는 각각 10.31%, 3.24%, 4.81% 였다. 또한, 이 450 mm 웨이퍼용 CCP 장비를 축대칭 2차원으로 형상화하고, 전극에 13.56 MHz를 직렬로 연결된 blocking capacitor ($1{\times}10^{-6}$ F/$m^2$)를 통해 인가할 수 있도록 상용 유체 모델 소프트웨어(CFD-ACE+, EXI corp)를 이용하여 계산하였다. 주요 전자-중성 충돌 반응으로 momentum transfer, ionization, excitation, two-step ionization을 고려했고, $Ar^+$와 $Ar^*$의 표면 재결합 반응은 sticking coefficient를 1로 가정했다. CFD-ACE+의 CCP 모델을 통해 Poisson 방정식을 풀어서 sheath와 wave effect를 고려하였다. Stochastic heating을 고려하지 않았을 때, 플라즈마 흡수 파워가 80 W, 160 W, 240 W에서 실험 투입 전력 200 W, 500 W, 1,000 W일 때와 유사한 반경 방향의 플라즈마 밀도 분포를 보였다. 200 W, 500 W, 1,000 W일 때의 전자밀도 분포는 수치 모델링과 전 범위에서 각각 10%, 3%, 2%의 오차를 보였다. 450 mm의 전극에 13.56 MHz의 전력을 인가할 때, 파워가 증가할수록 전자밀도의 최대값의 위치가 웨이퍼 edge에서 중심으로 이동하고 있음을 실험과 모델링을 통해 확인할 수 있었다.

• Journal of Korean Clinical Nursing Research
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• v.18 no.3
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• pp.354-367
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• 2012

Purpose: This study was done to verify validity and reliability of a neonatal patient classification system (NeoPCS-1). Methods: An expert group of 8 nurse managers and 40 nurses from 8 Neonatal Intensive Care Units in Korea, verified content validity of the measurement using item level content validity index (I-CVI). The participants were nurses caring for 469 neonates. Data were collected from November 11 to December 14, 2011 and analyzed using descriptive statistics, ANOVA, intraclass correlation coefficient, and K-cluster analysis with PASW 18.0 program. Results: Nursing domains and activities included 8 items with 91 activities. I-CVI was above .80 in all areas. Interrater reliability was significant between two raters (r=.95, p<.001). Classification scores for participants according to patient types and nurses' intuition were significantly higher for the following patients; gestational age (${\leq}29$ weeks), body weight (<1,000 gm), and transfer from hospital. Six groups were classified using cluster analysis method based on nursing needs. Patient classification scores were significantly different for the groups. Conclusion: These results show adequate validity and reliability for the NeoPCS-1 based on nursing needs. Study is needed to refine the measurement and develop index scores to estimate number of nurses needed for adequate neonatal care.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.889-893
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• 1998

In this research, mathematical models for predicting the shelf life of packaged tofu in a polyethylene container were developed. Transfer of oxygen in air through the package and then diffusion of oxygen into the filled water and the tofu with the simultaneous oxygen consumption by micoorganisms were studied. The results of simulation showed that the increase of microorganisms in the filled water was more than that in tofu. As a result, it turns out that the shelf life of packaged tofu was not determined by the number of microorganisms in the tofu, but by that in the filled water. Additionally, the effects of physical properties of packaging material and packaged materials, such as the oxygen permeability of packaging material, oxygen diffusion coefficient and the initial oxygen concentration in filled water, and the depth of the filled water, on the shelf life of packaged tofu, were observed.

• Journal of Korean Public Health Nursing
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• v.26 no.3
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• pp.440-452
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• 2012

Purpose: The purpose of this study was to provide basic data for use in development of strategy for healthy aging preparation and successful transfer to old age by identifying factors influencing quality of life of the baby boom generation. Methods: The data were collected from a total of 205 members of the baby boom generation(aged 48 to 56), and analysis was performed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient, and stepwise multiple regression using the SPSS(Version19.0) program. Results: Burden for taking care of children, aging anxiety, preparations for old age, and quality of life according to the general characteristics and health-related characteristics commonly showed a significant difference in education level and presence of stress. The greater the more burden for taking care of children and the deeper the aging anxiety, the lower the quality of life, and the better prepared for aging, the higher the quality of life. Factors affecting quality of life in the baby boom generation included preparations for old age, burden for taking care of children, monthly household income, and quality of sleep. Explanatory power was 32%. Conclusion: For successful transition to old age and for improvement of quality of life in the baby boom generation, a comprehensive approach in micro and macro dimensions will be sought.

• KSBB Journal
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• v.17 no.3
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• pp.241-246
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• 2002

Today, many problems of dye-processing wastewaters were raised due to industry of dyeing and textiles. It is difficult to treat them perfectly because they contain many poorly degradable matters, such as surfactants, ethylene glycol, polyvinyl alcohol, and so on. To improve the performances of conventional physicochemical treatment and activated sludge process, new systems of combining jet-loop reactor (JLR) with physicochemical treatment were developed. Volumetric oxygen transfer coefficient ($k_{L}a$) of JLR was significantly larger than that of air-lift reactor. Also, for the effective treatment of dye-processing wastewater, JLR with active carbon supports (JLRAS) were investigated. Removal efficiency of BOD, $COD_{Mn}$, $COD_{Cr} and color were found as 99, 86, 84, 83%, respectively, when HRT was 8 hrs. And performance of JLRAS was rapidly restored after step change of $COD_{Mn}$ loading late. The optimal coagulant and dosage of second physicochemical treatment after JLRAS were polyferric sulfate and 130 mg/L, respectively, when removal efficiencies of $COD_{Mn} and color were 85 and 73%, respectively. In conclusion, this system enables the reduction of operation cost, and the effective removal of many organics.