• 설비공학논문집
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• 제28권7호
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• pp.293-298
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• 2016

A three-dimensional (3D) numerical model of the vertical ground-coupled heat exchanger is useful for analyzing the modern ground source heat pump system. Furthermore, a detailed description of the inner side of the exchanger allows to account for the effects of the thermal capacity. Thus, both methods are included in the proposed numerical model. For the ground portion, a FDM (Finite Difference Method) scheme has been applied using the Cartesian coordinate system. Cylindrical grids are applied for the borehole portion, and the U-tube configuration is adjusted at the grid, keeping the area and distance unchanged. Two sub-models are numerically coupled at each time-step using an iterative method for convergence. The model is validated by a reference 3D model under a continuous heat injection case. The results from a periodic heat injection input show that the proposed thermal capacity model reacts more slowly to the changes, resulting in lower borehole wall temperatures, when compared with a thermal resistance model. This implies that thermal capacity effects may be important factors for system controls.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1625-1628
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• 2006

Two different negative-type photosensitive polyimides were synthesized and characterized for an application as an interdielectric layer in TFTLCD array. In the case of photocurable polyimides, the photosensitive moiety, 2-HHSP, was synthesized through 3 step reaction, and then was incorporated into side chains of polyimide precursor by post reaction. Optimum compositions of negative-type photocurable polyimde were also formulated. For photopolymerizable polyimides, two novel UV monomers containing imide linkages were prepared. An aqueous alkaline developable polymer matrix was synthesized by free radical copolymerization. A negative photoresist formulation was developed utilizing synthesized UV monomers containing imide linkage, photoinitiator, UV oligomer, and alkali developable polymer matrix. It was found that viaholes with good resolution, high transmittance and thermal resistance could be obtained by photolithographic process utilizing the negative-type photoresist formulations.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.872-875
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• 2003

Carbon nitride($CN_x$) thin films were deposited on quartz substrates using reactive RF magnetron sputtering system at uarious deposition conditions and investigated dielectric characteristics. Samples for capacitance measurements were of the MIM(Metal-Insulator-Metal) type devices. Aluminum film electrodes were prepared by a vacuum thermal evaporation method before and after the deposition of carbon nitride films. Capacitances were measured by a FLUKE PM6306 RCL Meter at room temperature. Current-voltage(I-V) characteristics and resistivity were measured by a CATS CA-EDA semiconductor test and analyzer. The carbon nitride films showed ${\alpha}-C_3N_4$ and ${\beta}-C_3N_4$ etc. peaks through Raman and FTIR. Observed surface of film and side structure using SEM(Scanning Electron Microscope), and measured thickness of film by ${\alpha}-step$. We can find that the dielectric constant was the lowest value in 50% nitrogen ratio and the resistivity was the highest value in 70% nitrogen ratio.

• 전자공학회논문지A
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• 제31A권5호
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• pp.113-120
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• 1994

Silicon flow sensor that can detect the velocity and direction of air flow was designed and fabricated by integrated circuit process and bulk micromachining technique. The flow sensor consists of three-layered dielectric diaphragm, a heater at the center of the diaphragm, and four thermopiles surrounding the heater at each side of diaphragm as sensing elements. This diaphragm structure contributes to improve the sensitivity of the sensor due to excellent thermal isolation property of dielectric materials and their tiny thickness. The flow sensor has good axial symmetry to sense 2-D air flow with the optimized sensing position in the proposed structure. The sensor is fabricated using CMOS compatible process followed by the anisotropic etching of silicon in KOH and EDP solutions to form I$\mu$ m thick dielectric diaphragm as the last step. TCR(Temperature Coefficient of Resistance) of the heater of the fabricated sensors was measured to calculate the operating temperature of the heater and the output voltage of the sensor with respect to flow velocity was also measured. The TCR of the polysilicon heater resistor is 697ppm/K, and the operating temperature of the heater is 331$^{\circ}C$ when the applied voltage is 5V. Measured sensitivity of the sensor is 18.7mV/(m/s)$^{1/2}$ for the flow velocity of smaller than 10m/s.

• 한국환경성돌연변이발암원학회지
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• 제15권2호
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• pp.106-114
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• 1995

A method was developed to detect total mutagenicity of fried fish for S. typhimurium TA98, using Ames assay. Method described herein circumvented problems associated with the sample preparation for Ames assay, i.e., a multi-purification step of sample and interference with solvent residuals. Experiment A, the best method developed in the present study, consisted of two important steps: pH adjustment of the aqueous sample solution from fried fish samples to remove impurities, and simultaneous distillation extraction (SDE) for partially purified samples to remove volatile compounds from solvents. The procedure and results were described as below. Fillet of gizzard shad (Konosirus punctatus) fish sample fried for 10 min each side on the temperature-controlled fry-pan (210$\circ$C) was homogenized in an aqueous acidic solution (pH 2) with a homogenizer, followed by filtration through Celite. The tiltrate (pH 2), removed some impurities by extraction with chloroform:methanol (2:1, v/v) mixture, was adjusted pH to 10 and then centrifuged to remove precipitate. The ethylacetate extract from the tiltrate of pH 10 was rotoevaporated and purified by SDE apparatus for 2 hours. Experiment A revealed significantly higher revertants (1928 per 25 g fried sample) than other Experiment (B, C, or D) tested. Experiment A gave good results in the mutagenicity test of fried fish sample with few purification steps using only 25 g fried sample and 650 ml of solvents; and thus this method could be a useful tool for the screening the mutagenicity or antimutagenicity of other foods as well.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.313-324
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• 2004

A rich phenomenon in the dynamics of azimuthal vortices in a circular cylinder caused by the inertial oscillation is investigated numerically at high Reynolds numbers and moderate Rossby numbers. In the actual spin-up flow where both the Ekman circulation and the bottom friction effects are included, the first appearance of a seed vortex is generated by the Ekman boundary-layer on the bottom wall and the subsequent roll-up near the corner bounded by the side wall. The existence of the small vortex then rapidly propagates toward the inviscid region and induces a complicated pattern in the distribution of azimuthal vorticity, i.e. inertial oscillation. The inertial oscillation however does not deteriorate the classical Ekman-pumping model in the time scale larger than that of the oscillatory motion. Motions of single vortex and a pair of vortices are further investigated under a slip boundary-condition on the solid walls. For the case of single vortex, repeated change of the vorticity sign is observed together with typical propagation of inertial waves. For the case of a pair of vortices with a two-step profile in the initial azimuthal velocity, the vortices' movement toward the outer region is resisted by the crescent-shape vortices surrounding the pair. After touching the border between the core and outer regions, the pair vortices weaken very fast.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 1998년도 제13회 하계학술발표회 논문집
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• pp.208-215
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• 1998

Since the advent of conceptual prototype and seminal application, the notion of national systems of innovation(NSI) has drawn an increasing recognition. Although the morphological entanglement is still ubiquitous and the theoretical underpinning is fragile, NSI seems to be the last step toward an increasingly complex and encompassing concept of innovation research. Inevitably, NSI necessitates the comparative analysis in that it normatively attempts to draw best practices. Unfortunately, national profiles are too complex and diverse to derive a unified, concrete representation of the system, posing the problem of defining and modelling NSI for international comparison. This paper aims at providing an inductive taxonomy of NSI based on R&D structure of OECD member economies. Based on the similarity among national profiles, clustering method was applied to identify seven clusters such as (1) enterprise-government funding and enterprise-education performing group, (2) enterprise-government funding and balanced performing group, (3) balanced funding and enterprise-education performing group, (4) balanced funding and performing group, (5) enterprise-dominating group, (6) government-education dominating group and (7) government-education funding and education performing group. This paper by nature is descriptive and exploratory. R&D structure represents a static snapshot of innovative performance since it accounts for only the input side of NSI and thus may not offer convincing explanations of the holistic innovation system. A more detailed and extensive analysis on the economic/technological performance across clusters will shed light on the promising avenue to future research.

• 가정과삶의질연구
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• 제28권1호
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• pp.1-11
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• 2010

The purpose of this study is to compare the cognition of SIDS as the first step for decreasing the SIDS death rate for the infant and for activity of infant-care in Korea. Participants were 409 child care center directors and 146 parents from 500 child care center directors and 200 parents who using child care center facilities for their children in Seoul. For analysis of research questions, frequencies, Cronbach $\alpha$, t-test,One-way ANOVA, Scheffee test were used with SPSSWIN 15.0. Through this study, we find the child care center directors have good cognition for it, but their effort for SIDS prevention is limited, because they don't have any official prevention education from authorized training center. Even though the parents have a low awareness for SIDS prevention than child care center directors, but they have high score in endeavor for SIDS precaution. Both child care center directors and parents want to receive systematic information from government side. Our infant should have a opportunity to grow up health and stability from reducing the risk of SIDS. In western countries such as U.S.A., U.K. and Japan have studied to decrease the SIDS death rate from thirty years ago, they have already government and social organization for preventing the SIDS. Nowadays, as you know well, our country birth-rate is falling by 1.08, therefore, it is important to decrease the infant death rate for keeping with our population. Also, it is relevant to the child-welfare and the child-safety and more better the child-care.

• Korean Chemical Engineering Research
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• 제47권3호
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• pp.327-331
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• 2009

보통의 2탑 증류시스템에서 사용하는 2기의 증류탑을 활용하여 열복합 증류시스템을 구성하고, 제안된 증류탑의 운전특성을 알아보기 위하여 시스템의 동특성을 조사하였다. 계단응답을 이용한 3가지 제품의 제어 방안을 알아내기 위하여, 상부제품의 유량, 중간제품의 유량, 재비기의 증기발생량을 변화하였다. 그 결과로부터 $3{\times}3$의 제어구조를 제시하였다. 제안된 제어시스템에 PI 제어기를 사용하였을 때의 제어성능을 조사한 결과 하부제품의 농도관리가 가장 어려움을 알 수 있었으나, 본 연구의 증류시스템 운전이 가능함을 알았다.

• 한국미생물·생명공학회지
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• 제27권2호
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• pp.96-101
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• 1999

Various side-chains are introduced to the 7-amino position of 7-aminocepha-losporanic acid (7-ACA) to make semi-synthetic cephalosporin antibiotics. In order to convert cephalosporin C (CPC) to 7-ACA, two enzymatic reactions are generally imployed. Glutary1-7-aminocephalosporanic acid (Gl-7-ACA) acylase is involved in the second step where the reaction intermediate, Gl-7-ACa is converted into 7-ACA. It was recently reported that CPC amidase can convert CPC directly into 7-ACA in a single enzymatic reaction. A study was undertaken to screen microorganisms conferring enzyme activity to convert Gl-7-ACA or CPC into 7-ACA by one or two enzymatic reactions. In order to screen the microorganisms rapidly, a non-$\beta$-lactam model compund, glutaryl-$\rho$-nitroanilide, was utilized in an early stage, thereafter the selected microorganisms were examined with real substrates. One microorganism exhibiting both Gl-7-ACA acylase and CPC amidase activities was obtained by the colorimetry method and HPLC assay, and was identified as a strain of Serratia species, designated as Serratia sp. N14.4. The optimal fermentation conditions for Serratia sp. N14.4 was pH9.0 and 3$0^{\circ}C$.