• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.190-200
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• 1991

Certain structural components are exposed to high temperatures. At high temperature, under thermal and mechanical loading, metal components exhibit both creep and plastic behavior. The unified constitutive theory is to model both the time-dependent behavior(creep) and the time-independent behavior(plasticity) in one set of equations. Microscopically both creep and plasticity are controlled by the motion of dislocations. A finite element method is presented encorporating a unified constitutive model for the transient analysis of viscoplastic behavior of structures exposed to high temperature.

• Korean Journal of Crystallography
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• v.4 no.1
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• pp.42-48
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• 1993

KTP(KTiOPO4) single crystals were grown by the TSSG(top seeded solution growth) method using the Ksp401s flux. A heat-pipe based growing furnace was used, and the temperature stability and the homogenity of the growing solution in the platinum crucible were within the level of It 0.5℃ and ±0.9℃, respectively. The effects of some operating variables such as operating temperature range, initial cooling rate, forced stirring, reuse of the flux were investigated. As the initial cooling rate was decreased to the degree of 0.1℃/hr and some proper stirring effect by the crystal rotation was introduced to the present experimental condition, bigger and better crystals without inclusion grew. A single crystal with the maximum sixte of 44 ×39 ×17mm3 was obtained and showed the SHG conversion efficiency of 21.39) even without the anti-refilection coating.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.935-942
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• 2019

This paper descries the operation of a heater which was designed to control a motor that generates an eddy current. As the motor drives the rotor of an eddy current heater, magnetic fields are provided within the air gap between an eddy current heater's rotor and stator. Throughout the research, a rotor composed of 8 and 16 pieces of magnets was used to analyze which are the factors that affect the efficiency of this equipment. Test results showed that the magnetic fields are influenced by variable functions including the velocity of a motor and the quantity of magnets composing a rotor.

• Korean Journal of Food Science and Technology
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• v.5 no.1
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• pp.36-41
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• 1973

Chemical changes with time of frying-fats during the frying process (beef tallow with 0.01% BHA and 0.01% BHT, turnover rate 9%/hr and $140{\pm}10^{\circ}C$ temperature) of Ramyon on a commercial scale were studied. No significant changes of carbonyl value and peroxide value were noted up to 120 hrs. However, small increases in acid value, color and dimeric fatty acid were noted. Small decreases in iodine value and the content of unsaturated fatty acids were also observed. Under the experimental storage condition, when the stability of fats heated were compared to fresh fat, minor differences in carbonyl value and weight gain were noted. All of these demonstrated that frying-fats commercially used in Ramyon frying system were maintained in good quality during the frying process.

• Journal of the Mineralogical Society of Korea
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• v.16 no.2
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• pp.125-133
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• 2003

Saponite was synthesized from talc by hydrothermal method. The starting material was prepared by adding ($NO_3$)$Al_3$$.$$9H_2$O and Mg($NO_3$)$_2$$.$$6H_2$O solution to the talc powder. which was previously activated in air at 800 $^{\circ}C$ together with $Na_2$$CO_3$. The alkalinity of the solution was controlled by $NH_4$OH solution. The autoclaving was carried out in the closed stainless steel vessel (about 1 liter) for 40 hours under the pressure of 25 kgf/$\textrm{cm}^2$ at $ 230^{\circ}C$ The characterization of the reaction product shows that saponite was crystallized successfully. After the experimental results, pressure was not sensitive parameter in the range of 25 ∼ 75 kgf/$\textrm{cm}^2$, but longer reaction time results in better crystallinity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.6
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• pp.734-737
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• 2006

This study was carried out to establish the manufacturing process of barley leaf powder tea. The optimal manufacturing process among many trials was determined with sensory evaluation. Finally established process and operation conditions were as follows: pretreatment (cutting and washing), steaming ($100^{\circ}C$, 30 sec), primary drying and roasting ($130^{\circ}C$, 40 min), rolling (RT, 25 min), middle drying and roasting ($60^{\circ}C$, 30 min), final drying and roasting ($55^{\circ}C$, 25 min), drying ($60^{\circ}C$, 20 min), roasting ($85^{\circ}C$, 20 min), and powdering (120 mesh). The barley leaf powder tea produced by this process mainly consisted of dietary fiber (33.8%), amino acids (12.9%), minerals (4.7%) and ${\beta}-carotene$ (6.9 mg%).

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.351-351
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• 2013

한국 전체 에너지 사용량 중약 24%의 에너지가 건축물 부분에 소비되고 있다. 건축물의 벽체나 유리창 등을 통해서 에너지 손실이 이루어지는데 유리창은 벽체에 비해 약 10배 이상 낮은 단열 특성을 가지고 있기 때문에 유리창을 통한 열손실량은 더 크다. 이러한 유리창 부분의 열손실 문제를 해결할 수 있는 방안으로 좋은 단열 특성 및 낮은 방사율을 가지고 있는 Low-e coating 방법을 사용하였다. 본 실험에서는 XG glass 기판 위에 IGZO/Ag/IGZO OMO 구조의 다층 박막을 증착하였다. RF magnetron sputtering방법을 이용하여 OMO 구조의 상부와 하부의 Oxide layer로 IGZO 박막을 증착하였다. 사용된 IGZO 타겟은 $In_2O_3$ (99.99%), $Ga_2O_3$ (99.99%), ZnO (99.99%)의 분말을 각각 1:1:1 mol% 조성비로 혼합하여 소결하여 제작하였다. Thermal Evaporator 장비를 이용하여 OMO 구조의 Metal layer로 Ag (99.999%)를 증착하였다. 실험 기판은 크기 $30{\times}30mm$의 0.7T XG glass를 사용하였다. OMO 구조의 산화층 IGZO 박막은 상/하층 동일 조건으로 기판 온도는 실온으로 고정하였으며, 초기 압력 $3.0{\times}10^{-6}$ Torr, 증착 압력 $3.0{\times}10^{-2}$ Torr, RF 파워 50W, Ar 유량 50 sccm로 고정시키고 증착 시간이 변화하면서 박막을 증착하였다. OMO 구조의 Metal layer로 Ag 증착 조건은 초기 진공도가 약 $6.0{\times}10^{-6}$ Torr 이하로 유지하고 기판을 2 Rpm의 속도로 회전시켰다. 이후 0.3 V로 Ag를 10분간 가열하여 충분히 녹인 후 Film Thickness Monitor로 두께를 확인하였다. OMO 다층 박막의 산화물층 변화에 따라 로이다층 박막의 구조적, 광학적 및 전기적 특성을 분석하였다. XRD 분석결과에 의하여 Bragg's 법칙을 만족하는 피크가 나타나지 않는 비정질 구조임을 확인할 수 있으며, AFM 분석결과에 통해서 최소 1.3 nm의 Roughness를 나타내었다. UV-Visible-NIR 분광광도계를 이용하여 다층 박막은 가시광선 영역에서 평균 80%의 광 투과성을 보여 IR 영역에서 평균 30% 투과하고 좋은 차단 특성을 나왔다. Low-e 특성을 갖는 유리창을 통해서 에너지 절약을 이룰 수 있는 것을 확인할 수 있었다.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.42-49
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• 2000

A new method for the quantitative determination of capsaicinoids in microcapsule has been developed. Among seventeen solvents tested for solubilizing wall material (gum arabic and modified starch) of microcapsule, dimethyl sulfoxide (DMSO) was selected as an optimal solvent. The most appropriate mixing ratio of microcapsule to DMSO for solubilizing wall material was 1 to 10(w/v). Appropriate carriersolubilizing temperature and time were $55^{\circ}C$ and 30 min, respectively. Also conditions for extracting oleoresin from the solubilized microcapsule were studied. The mixing ratio of ethanol to DMSO was optimal at 8 to 1(v/v). Optimized vortexing time was 5 min at 40㎐. Pecipitant was obtained by centrifugation at 21000 rpm for 15 min. The precipitant was reextracted with ethanol. The extracted supernatants were combined and adjusted to final volume of 25 ml. Extracted solutions were analyzed for quantitation of total capsaicinoids by employing HPLC and for quantitation of total carotenoids by spectrophotometric method. This method can be used to monitor changes of capsacinoid during manufacturing or storage of red pepper oleoresin microcapsule powder.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.187-194
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• 2019

The off-axis Infra-Red(IR) seeker is mounted on the nose cone side of the anti-air high speed missile to alleviate thermal shield effect due to aerodynamic heating. The seeker output can not be regarded as the Line-of-Sight(LOS) rate any more as missile's roll motion to keep the target tracking is associated. In this paper, we propose a method to calculate the LOS rate for off-axis seeker on a 2-axis gimbal. Firstly, true LOS rate equations are analytically derived but not implementable because boresight error rate is not measurable. And then the first order lag approximation to obtain boresight error rate is proposed. The proposed LOS rate calculation method can compensate the coupling effect by considering the rotations of missile and gimbal. The performance of the proposed method is verified via full nonlinear 6-DOF(Degree of Freedom) simulations.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.405-414
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• 2008

To better understand the physical processes that control the high-latitude lower thermospheric dynamics, we analyze the divergence and vorticity of the high-latitude neutral wind field in the lower thermosphere during the southern summertime for different IMF conditions. For this study the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEG CM) is used. The analysis of the large-scale vorticity and divergence provides basic understanding flow configurations to help elucidate the momentum sources that ulti-mately determine the total wind field in the lower polar thermosphere and provides insight into the relative strengths of the different sources of momentum responsible for driving winds. The mean neutral wind pattern in the high-latitude lower thermosphere is dominated by rotational flow, imparted primarily through the ion drag force, rather than by divergent flow, imparted primarily through Joule and solar heating. The difference vorticity, obtained by subtracting values with zero IMF from those with non-zero IMF, in the high-latitude lower thermosphere is much larger than the difference divergence for all IMF conditions, indicating that a larger response of the thermospheric wind system to enhancement in the momentum input generating the rotational motion with elevated IMF than the corresponding energy input generating the divergent motion. the difference vorticity in the high-latitude lower thermosphere depends on the direction of the IMF. The difference vorticity for negative and positive $B_y$ shows positive and negative, respectively, at higher magnetic latitudes than $-70^{\circ}$. For negative $B_z$, the difference vorticities have positive in the dusk sector and negative in the dawn sector. The difference vorticities for positive $B_z$ have opposite sign. Negative IMF $B_z$ has a stronger effect on the vorticity than does positive $B_z$.