• 한국재료학회지
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• 제28권3호
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• pp.159-165
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• 2018

In order to increase the efficiency of the sputtering method widely used in thin film fabrication, a dc sputtering apparatus which supplies both high frequency and magnetic field from the outside was fabricated, and cobalt thin film was fabricated using this apparatus. The apparatus can independently control the applied voltage, the target-substrate distance, and the target current, which are important parameters in the sputtering method, so that a stable glow discharge is obtained even at a low gas pressure of $10^{-3}$ Torr. The fabrication conditions using the sputtering method were mainly performed in $Ar+O_2$ mixed gas containing about 0.6 % oxygen gas under various Ar gas pressures of 1 to 30 mTorr. The microstructure of Co thin films deposited using this apparatus was examined by electron diffraction pattern and X-ray techniques. The magnetic properties were investigated by measuring the magnetization curves. The microstructure and magnetic properties of Co thin films depend on the discharge gas pressure. The thin film fabricated at high gas pressure showed a columnar structure containing a large amount of the third phase in the boundary region and the thin film formed at low gas pressure showed little or no columnar structure. The coercivity in the plane was slightly larger than that in the latter case.

• 한국산학기술학회논문지
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• 제10권4호
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• pp.785-794
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• 2009

워게임모델에서 가상환경격자정보에 관한 개선과 구축기법을 연구하였다. 가상환경자료는 지상, 해상, 공중으로 구분하여 관리 및 운용한다. 가상환경자료는 지리정보와 지형형태정보로 구축 및 관리한다. 지리정보는 격자(Grid) 형태로서 격자위치좌표와 수심을 파일로 관리한다. 그 격자정보파일의 수심값을 이동가능대표값(GCV)으로 개선하고, 조석차가 심한지역에 대해서 동적가상환경구축기법을 제안하였다. 제안된 시스템 의 구현 및 시험을 통하여 동적 가상환경을 워게임모델에 적용이 가능하다는 것을 알 수 있었다.

• 한국산학기술학회논문지
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• 제10권6호
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• pp.1361-1368
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• 2009

본 연구는 충청지역를 대상으로 하여 지역산업연관분석을 실시함으로써 지역경제활성화를 위한 산업선정과 투자우선순위 등을 제시하고자 함이다. RAS기법을 이용하여 2005년 전국산업연관표를 바탕으로 2006년 전국산업연관표를 작성한 후에, 입지계수법을 이용하여 2006년 충청지역산업연관표를 작성하여, 충청지역의 각종 파급효과들을 분석하였다. 생산유발효과, 부가가치 유발효과 분석결과는 제조업부문이 가장 높게 나타났으며, 취업유발효과의 경우 음식점 및 숙박업이 가장 높게 나타났으며, 감응도계수는 광업, 영향력계수는 제조업부문에서 높게 분석되었다.

• 반도체디스플레이기술학회지
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• 제8권3호
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• pp.31-37
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• 2009

This paper presents one and two dimensional simulation results with discontinuous features (shocks) of capacitively coupled rf plasmas. The model consists of the first two and three moments of the Boltzmann equation for the ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The local field and drift-diffusion approximations are not employed, and as a result the charged species conservation equations are hyperbolic in nature. Hyperbolic equations may develop discontinuous solutions even if their initial conditions are smooth. Indeed, in this work, secondary electron emission is shown to produce transient electron shock waves. These shocks form at the boundary between the cathodic sheath (CS) and the quasi-neutral (QN) bulk region. In the CS, the electrons emitted from the electrode are accelerated to supersonic velocities due to the large electric field. On the other hand, in the QN the electric field is not significant and electrons have small directed velocities. Therefore, at the transition between these regions, the electron fluid decelerates from a supersonic to a subsonic velocity in the direction of flow and a jump in the electron velocity develops. The presented numerical results are consistent with both experimental observations and kinetic simulations.

• 센서학회지
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• 제27권6호
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• pp.407-413
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• 2018

Most sleep apnea patients exhibit severe snoring, and long-lasting sleep apnea may cause insomnia, hypertension, cardiovascular diseases, stroke, and other diseases. Although polysomnography is the typical sleep diagnostic method to accurately diagnose sleep apnea by measuring a variety of bio-signals that occur during sleep, it is inconvenient as the patient has to sleep with attached electrodes at the hospital for the diagnosis. In this study, a diagnostic pillow is designed to measure respiration, heart rate, and snoring during sleep, using only one polyvinylidene fluoride (PVDF) sensor. A PVDF sensor with piezoelectric properties was inserted into a specially made instrument to extract accurate signals regardless of the posture during sleep. Wavelet analysis was used to identify the extractability and frequency domain signals of respiration, heart rate, and snoring from the signals generated by the PVDF sensor. In particular, to separate the respiratory signal in the 0.2~0.5 Hz frequency region, wavelet analysis was performed after removing 1~2 Hz frequency components. In addition, signals for respiration, heart rate, and snoring were separated from the PVDF sensor signal through a Butterworth filter and median filter based on the information obtained from the wavelet analysis. Moreover, the possibility of measuring sleep apnea from these separated signals was confirmed. To verify the usefulness of this study, data obtained during sleeping was used.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.407-410
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• 2012

The properties of Al-doped ZnO (AZO) films were investigated as a function of H2/(Ar + H2) gas ratio using an AZO (2 wt% Al2O3) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at 200 ℃ and in 2 × 10-2Torr working pressure and with various ratios of H2/(Ar + H2) gas. During the AZO film deposition process, partial H2 gas affected the AZO film characteristics. The electron resistivity (~ 9.21 × 10-4 Ωcm) was lowest and mobility (~17.8 ㎠/Vs) was highest in AZO films when the H2/(Ar + H2) gas ratio was 2.5%. When the H2/(Ar + H2) gas ratio was increased above 2.5%, the electron resistivity increased and mobility decreased with increasing H2/(Ar + H2) gas ratio in AZO films. The carrier concentration increased with increasing H2/(Ar + H2) gas ratio from 0% to 7.5%. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90% and an orientation of the deposition was [002] orientation for AZO films grown with all H2/(Ar + H2) gas ratios.

• 한국식생활문화학회지
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• 제25권5호
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• pp.516-524
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• 2010

Consumers are highly interested in processed fishery products that are healthy and superior in terms of convenience, nourishment, and taste. However, current domestic research on processed fishery products is marginal. We systematically analyzed consumer consumption patterns and the relationship to pursuit benefits, selection attributes, satisfaction levels, and reasons for purchase. Consumers considered product information the most important selection attribute, whereas convenience scored highest for pursuit benefits. Furthermore, the influences of selection attributes and pursuit benefits on satisfaction level and the reason for purchasing an item were analyzed using demographic properties as control variables. The variables that affected satisfaction level were residential district (region: B= -0.268, p<0.05.), recipe (B=0.098, p<0.05), nutrients (B=0.124, p<0.05), convenience (B=0.283, p<0.001), and economics (B=0.138, p<0.05). The variables affecting the reason for purchasing were nutrients (B=0.173, p<0.001), convenience (B=0.277, p<0.001) and satisfaction level (B=0.163, p<0.001). Pursuit intention had significant effects on purchase intention; however, selection attributes had no significant effect on purchase intention. Therefore, consumer satisfaction had a significant effect on purchase intention. This result showed that if consumers were satisfied, they intended to repurchase. Attempts to increase repurchases by consumer are needed by fulfilling consumer satisfaction. These data can be utilized as a fundamental reference for sales promotions.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.223-223
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• 2022

Saengcheonggukjang, known as Natto in Japan, is a Korean fermented soybean food that has various bioactive compounds for antioxidant and antidiabetic activity. The development of soybean (Glycine max L.) cultivars for saengcheonggukjang production relies on the selection of seed traits that influence the quality and sensory properties. One of the important traits for cultivars is seed characteristics such as seed hardness and size. In order to select the lines for breeding good quality saengcheonggukjang varieties, several simple sequence repeat (SSR) markers and quantitative trait loci (QTLs) related to seed quality of Korean cultivars, Pungsannamulkong, Socheongja, Pungwon, Heawon, and Hoseo, were analyzed. Based on the many studies to detect stable QTLs for seed traits, we tested several QTLs related to seed size and water absorbability using SSR markers on Korean cultivars. The results showed that two regions for water absorbability of Pungsannamulkong and one region for seed size traits of Haewon and Hoseo were identified in this study. These results could have applications to soybean breeding for seed size and hardness and it is necessary to narrow it down through further study.

• Tribology and Lubricants
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• 제34권3호
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• pp.93-107
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• 2018

The purpose of Part I of this study is to find the potential region of wear scarring on engine journal bearings operating at a constant angular crank shaft velocity under firing conditions. To do this, we calculate the applied loads and eccentricities of a big-end journal bearing installed on a four-stroke and four-cylinder engine at every crank angle. Then, we find potential wear regions, such as a minimum oil film thickness, at every crank angle below most oil film thickness scarring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Thus, the wear region is defined as a set of each film thickness below the MOFTSW at every crank angle. In this region, the wear volume changes according to the wear depth and wear angle, depending on the minimum oil film thickness at every crank angle. The total wear volume is the summation during one cycle. Graphical views of the region in the two-dimensional coordinates show the crank angle and bearing angle along the journal center path, indicating the position of the minimum oil film thickness. The results of wear analysis show that the possible wear region is located at a few tens of angles behind the upper center of a big-end bearing at maximum power rpm.

• 한국재료학회지
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• 제30권6호
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• pp.301-307
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• 2020

In this study, factors considered to be causes of promotion of densification of sintered pellets identified during phase change are reviewed. As a result, conclusions shown below are obtained for each factor. In order for MA powder to soften, a temperature of 1,000 K or higher is required. In order to confirm the temporary increase in density throughout the sintered pellet, the temperature rise due to heat during phase change was found not to have a significant effect. While examining the thermal expansion using the compressed powder, which stopped densification at a temperature below the MA powder itself, and the phase change temperature, no shrinkage phenomenon contributing to the promotion of densification is observed. The two types of powder made of Ti-silicide through heat treatment are densified only in the high temperature region of 1,000 K or more; it can be estimated that this is the effect of fine grain superplasticity. In the densification of the amorphous powder, the dependence of sintering pressure and the rate of temperature increase are shown. It is thought that the specific densification behavior identified during the phase change of the Ti-37.5 mol.%Si composition MA powder reviewed in this study is the result of the acceleration of the powder deformation by the phase change from non-equilibrium phase to equilibrium phase.