• 한국정밀공학회지
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• 제33권11호
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• pp.893-898
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• 2016

Plastic array lens are cheap to manufacture; however, plastic is not resistant to high temperatures and moisture. Optical glass represents a better solution but is a more-expensive alternative. Glass array lens can be produced using lithography or precision-molding techniques. The lithography process is commonly used, for instance, in the semiconductor industry; however, the manufacturing costs are high, the processing time is quite long, and spherical aberration is a problem. To obtain high-order aspherical shapes, mold-core manufacturing is conducted through ultra-precision grinding machining. In this paper, a $4{\times}1$ mold core was manufactured using an ultra-precision machine with a jig for the injection molding of an aspherical array lens. The machined mold core was measured using the Form TalySurf PGI 2+ contact-stylus profilometer. The measurement data of the mold core are suitable for the design criterion of below 0.5 um.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.429-431
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• 2010

The hybrid geoid model should be determined by fitting the gravimetric geoid to the geometric geoid which were presented the local vertical level. Therefore, it is necessary to find firstly the optimal scheme for improving the accuracy of gravimetric geoid in order to development the high-precision hybrid geoid model. Through finding the optimal scheme for determining the each part of gravimetric geoid, the most accurate gravimetric geoid model in Korea will be developed when the EIGEN-CG03C model to degree 360, 4-band spherical FFT and RTM reduction methods were used for determining the long, middle and short-frequency part of gravimetric geoid respectively. Finally, we developed the hybrid geoid model around Korea by correcting to gravimetric geoid with the correction term. The correction term is modelled using the difference between GPS/Levelling derived geoidal heights and gravimetric geoidal heights. The stochastic model used in the calculation of correction term is the LSC technique based on second-order Markov covariance function. 503 GPS/Levelling data were used to model the correction term. The degree of LSC fitting to the final hybrid geoid model in Korea was evaluated as 0.001m ${\pm}0.054m$.

• 분석과학
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• 제13권6호
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• pp.705-711
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• 2000

리튬 이차전지용 부극 재료로 페놀 수지로 부터 유도된 boron을 doping한 polyacene에 구조적 특성, 표면 특성 및 전기적 특성을 연구하였다. Polyacene탄소질에 boron의 함유량을 각각 5%, 10%, 15%, 20% 첨가하여 특성화하였다. X-선 회절 결과에 따르면, 이들 시료들은 대표적인 무정형 탄소의 회절형태를 나타내었다. 표면 상태는 반구형의 표면상태를 가지고 있음을 SEM 결과로부터 알 수 있었다. 전지의 이온과 전자전달효과를 알아보기 위한 전기 화학적 충전/방전 특성과 임피던스 측정의 결과에 의하면, 10%와 15% boron이 첨가된 시료는 다소 우수한 특성을 나타내고 있다.

• 유공압시스템학회논문집
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• 제1권2호
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• pp.8-14
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• 2004

Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

• 스마트미디어저널
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• 제1권4호
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• pp.18-26
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• 2012

스마트폰 어플리케이션 수의 증가는 새로운 유저인터페이스에 대한 중요성을 증대시켰으며, 다양한 센서를 융합한 유저인터페이스 개발 연구의 관심을 유도하고 있다. 본 논문에서는 스마트폰에 있는 가속도 센서, 자계 센서, 자이로 센서 정보를 융합하여 사용자 모션 제스처를 인식할 수 있는 새로운 유저인터페이스를 제안한다. 제안 방법은 유합 센서 정보로부터 스마트폰의 3차원 방위 정보를 구하고, HMM(Hidden Markov Model)을 이용하여 손동작 제스처를 인식한다. 특히 제안된 스마트폰의 3차원 방위 좌표계를 구면 좌표계로 변환하는 양자화 방법은 기본 축 회전에 더욱 민감한 인식이 이루어지도록 하였다. 실험을 통하여 제안한 방법이 93%로의 인식률을 보였다.

• 천문학회보
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• 제41권1호
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• pp.47.1-47.1
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• 2016

The determination of three dimensional parameters (e.g., radial speed, angular width, source location) of Coronal Mass Ejections (CMEs) is very important for space weather forecast. To estimate these parameters, several cone models based on a flat cone or a shallow ice-cream cone with spherical front have been suggested. In this study, we investigate which cone model is proper for halo CME morphology using 26 CMEs which are identified as halo CMEs by one spacecraft (SOHO or STEREO-A or B) and as limb CMEs by the other ones. From geometrical parameters of these CMEs such as their front curvature, we find that near full ice-cream cone CMEs are dominant over shallow ice-cream cone CMEs. Thus we develop a new full ice-cream cone model by assuming that a full ice-cream cone consists of many flat cones with different heights and angular widths. This model is carried out by the following steps: (1) construct a cone for given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, (4) minimize the difference between the estimated projection speeds with the observed ones. We apply this model to 12 SOHO halo CMEs and compare the results with those from other stereoscopic methods (a geometrical triangulation method and a Graduated Cylindrical Shell model) based on multi-spacecraft data.

• 한국식품영양과학회지
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• 제27권2호
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• pp.259-267
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• 1998

Typical characteristics of Mejus must be understood to get the basic data for setting up mass production system of traditional fermented soybean products. One hundred and twenty one Mejus were collected from various places and analyed. Most of shapes were rectangular and some were spherical, conical, cylindrical and doughnut types. The weight of Mejus was 0.4~4.2kg. Chemical analysis showed: moisture content, 9.73~58.22% ; pH, 4.95~8.15; acidity, 0.6~3.8% ; soluble protein content, 4.45~12.31%; soluble sugar content, 0.82~10.95%. Enzyme assay showed: $\alpha$-amylase activity, 5.0~874.2 units/g; $\beta$-amylase activity, 0.02~27.74units/g; acidic protease activity, 31.3~225.1unts/g; lipase activity 1.0~53.0units/g. Total viable cells were 3.72$\times$107~1.35$\times$1010cfu/g, and yeast and mold count 6.46$\times$104~8.91$\times$106cfu/g. respectively. $\alpha$-Amylase activity of a traditional Meju from Incheon showed the highest activity of 732.8 units/g(interior section) and 823.2units/g (exterior section). $\beta$-Amylase activity was the highest{3.57 units/g (interior sectin) and 4.25units/g (exterior section)} in Meju from Chunbuk. Acidic protease activity was the highest in sample from Seoul, whereas traditional Meju from Kyongnam showed the highest activity of 21.5units/g(interior section) and 37.5units/g(exterior sectin).

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2523-2531
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• 2009

Effects of some diacid, diamine and dinitro aromatic compounds on the structure and activity of adenosine deaminase (ADA) were investigated by UV-Vis spectrophotometry in 50 mM phosphate buffer at pH = 7.5 and 27 ${^{\circ}C}$ and molecular docking studies. The results showed that all tested ligands are showing inhibition; five ligands are uncompetitive and other two ligands are mixed of competitive and noncompetetive inhibitors with majority of competitive behavior. For the later case analysis was done based on competitive inhibition. Diacids have larger size and higher inhibition constant ($K_I$) relative to others. A logical correlation between calculated free energy of binding and experimental values was obtained for un-competitive. Experimental and calculated data showed that competitive inhibitors are distributed near the active site of enzyme and form several cluster of ranks, whereas uncompetitive inhibitors bind to the enzyme-substrate complex and distributed far from the active site. Results of structure-activity relationship showed that, larger, more hydrophobe, less spherical and more aromatic ligands have higher inhibition constants.

• 천문학회지
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• 제33권2호
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• pp.127-135
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• 2000

We investigate the effects of planetary rotation on the exospheres of the earth and Mars with simple collisionless models. We develope a numerical code that computes exospheric densities by integrating velocity functions at the exobase with a 10 point Gauss method. It is assumed in the model that atoms above the exobase altitude move collisionlessly on an orbit under the planet's gravity. Temperatures and densities at the exobase over the globe are adopted from MSIS-86 for the earth and from Bougher et al's MTGCM for Mars. For both the earth and Mars, the rotation affects the exospheric density distribution significantly in two ways: (1) the variation of the exospheric density distribution is shifted toward the rotational direction with respect to the variation at the exobase, (2) the exospheric densities in general increase over the non-rotating case. We find that the rotational effects are more significant for lower thermospheric temperatures. Both the enhancement of densities and shift of the exospheric distribution due to rotation have not been considered in previous models of Martian exosphere. Our non-spherical distribution with the rotational effects should contribute to refining the hot oxygen corona models of Mars which so far assume simple geometry. Our model will also help in analyzing exospheric data to be measured by the upcoming Nozomi mission to Mars.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.315-316
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• 2006

The paper presents some results regarding the obtaining of some copper heat pipes with a porous copper internal layer for electronic components cooling. The heat pipes were realized by sintering of spherical copper powders of $90{\div}125\;{\mu}m$ size directly on the internal side of a copper pipe of 18 mm in diameter. The obtained pipes were then brazed in order to obtain a heat pipe of 0.5 m in length. After that, the heat pipe was sealed and filled with a small quantity of distilled water as working fluid. To establish the total heat transport coefficient and the thermal flow transferred at the evaporator, some external devices were realized to allow the heating of the evaporator and the cooling of the condenser. Water heat pipes are explored in the intermediate temperature range of 303 up to 500 K. Test data are reported for copper water heat pipe, which was tested under different orientations. The obtained results show that the water heat pipe has a good thermal transfer performance in the temperatures range between 345 and 463 K.