• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.76-80
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• 2014

Toroidal cores made of metallic powder requires large magnetic field strength up to few decade kA/m to obtain major hysteresis loop. To overcome thermal heat generation problem from large exciting current during measurement, we have employed a real time hysteresis loop tracer which can digitize and calculate B-H signals in personal computer as real time. For example, when we magnetize specimen at 10 Hz frequency, we could display hysteresis loops 10 times per second. Using the real time hysteresis loop tracer, we could measure major hysteresis loop of toroidal shape metallic powder core at maximum flux density or maximum magnetic field strength to be measured within 5 second not to significant increasement of specimen temperature due to the heat dissipation from coil windings. For the constructed hysteresis loop tracer, we could measure hysteresis loop at magnetic field strength higher than 50 kA/m for the toroidal shape specimen.

• Journal of Embryo Transfer
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• v.7 no.2
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• pp.117-124
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• 1992

미성숙 래트의 외경정맥에 카테타를 장착하고, 다음날 (28일령) 대조군에는 4IU, 다배란 처치 군에는 20IU의 PMSG를 피하주사하였다. 각 실험동물은 혈중의 LH농도 변화를 측정하기 위하여 PMSG 투여 직전 (0시간), 투여후 12시간, 그 이후 6시간 간격으로 혈액을 채취하고 72시간에 희생시켰다. 그 결과 다배란 용량의 PMSG 투여는 먼저 배란반응 및 난소중량을 대조군에 비하여 각각 4,7배 및 2.1배나 현저하게 (P<0.05) 증가시켰다. 그리고 혈청 LH농도는 Radioimmunoassay(RIA)에 의하여 결정되었는데, 먼저 두 군 모두 두 개의 분명한 peak을 가진 경시적 변화관계를 보였다. 즉 이들 두 군네 있어서 LH농도 변화는 0-18시간대에 처음으로 완만한 증가와 54-60시간대에 두번째는 급격한 증가(surge)를 보였다. 그러나 두 군간에 LH농도의 크기는 현저하게 달라, 다배란처치군의 동물에 있어서는 두번째의 LH peak에 앞서 전반적인 LH농도가 대조군보다 현저하게 (P<0.001) 높았으며, 반대로 PMSG 투여후 60시간에 일어나는 peak에 있어서는 LH농도가 대조군보다 현저하게 (P<0.001) 54%나 낮았다. 덧붙여 두 peak간의 증가폭은 대조근에 비하여 다배란 처치군에서 훨씬 낮았다. 본 열구 결과는 PMSG 처치된 래트에 있어서 두 가지의 분명한LH peak의 존재를 정의하며, 다배란 처치에 따른 난소과잉 자극과 내인성 LH surge의 감소와의 연관성을 밝힌다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1997.10a
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• pp.52-54
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• 1997

고주파 유도결합 플라즈마(RFICP)에서 루우프법에 의해 자기장특성을 계측하였다. 자기장 계측은 플라즈마의 거시적 변화를 시간적으로 접근하며, 반도체 프로세스의 관건인 균일하고, 고집적인 분포를 얼마나 교란, 응집하는가를 검증하고, 밀도와의 관계를 비교, 분석하여 방적의 최적화를 규명할 수 있을 것이다. 작은 루우프 안테나($\Phi$:외경 7.5mm)는 RF 자기장의 크기와 방향을 결정하기 위해 방전속에 삽입된다. 자기장의 세기는 전형적으로 입력파워 50 - 500 [W]에 대해 0.1에서 2.5 G 사이로 변화하였다. 사용가스는 아르곤가스(99.9% 고순도)를 사용하였으며, 동작압력은 20 [mTorr] 에서 15 [sccm]까지하였다. 반경방향의 공간분포에서는 아스펙트비(aspect ratio : R/L)를 2로 하여 자기장 분포를 계측하였다. 자기장은 입력파워의존성에 대해서 200 [W]까지 상승하고, 300[W]에서 안정성을 지속한다. 압력에 대한 의존성은 300[W]에서 60 [mTorr]이상 일 때는 플라즈마의 균질한 압력상태를 벗어남을 보인다. 아르곤 가스유량에 대해서는 무거운 중성기체입자가 자기장의 영향을 거의 받지 않기 때문에 일정한 경향이 나타났다. 반경방향의 공간분포 측정에서는 자기장은 RFICP의 대구경 특성에 맞게 전체적으로 일정한 분포를 이루고 있음을 확인하였다. 이러한 결과로부터 고주파유도결합 플라즈마에서의 동작생성, 유지기구등의 파악에 도움이 될 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.232-241
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• 2017

This paper presents an automated cow-feeding system based on an AGV and screw conveyor for domestic livestock farms, which are becoming larger and more commercialized. The system includes a hopper module for loading pellet-type mixed feed at the top of the system, a transfer module mounted with a screw conveyor to transfer feed from the hopper module to the outlet module, an outlet module composed of belt conveyors, and an electromagnetic guided driving-type AGV. The weight of the loaded feed is measured by a load cell located under the transfer module. The system reads the feed discharge information stored in RFID tags installed in each cowshed cell, and a predetermined amount of feed is discharged while the AGV is moving. A cow-feed test system was constructed to determine the design parameters of the screw conveyor in the transfer module that determine the feeding capacity. These parameters include the screw's outer diameter, the screw shaft outer diameter, and screw pitch. The parameters were applied to the finalized cow-feed system construction. A DSP-based main controller and cow-feeding algorithm for different scenarios were also developed to control the system. Experimental results confirmed that the system could supply a total of 21 kg of feed uniformly at 420 g/s for a cowshed cell which has 7 cows. The driving distance was 5 m and the speed was 0.1 m/s. Thus, the proposed system could be applied to standardized domestic livestock farms.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.952-959
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• 2012

The photocatalytic reactor was designed to have improved efficiency by enhancing a light intensity of photocatalytic reactor using a reflector coated on the surface at the outer radius of annular shaped photocatalytic reactor. The improved photocatalytic reactor performed to treat waste air containing malodor and VOC with the enhanced light intensity, of which the effect on their removal efficiency was investigated. The intensities of illumination of the improved photocatalytic reactor filled with porous silica-based media and nonporous glass bead media carrying photocatalyst were observed to increase by 28.5% and 30.1%, respectively, compared to those of photocatalytic reactor without any reflector. Using the improved photocatalytic reactor filled with porous silica-based media and nonporous glass bead media carrying photocatalyst, the removal efficiencies were enhanced by 2~3% and insignificantly, respectively. The removal efficiencies of the optimized photocatalytic reactor with reflectors, filled with porous silica-based media carrying photocatalyst, were observed to increase by 26% and 60%, compared to those of photocatalytic reactor (i.e., 19% and 53%), without any reflector, filled with nonporous glass bead media carrying photocatalyst, for hydrogen sulfide and toluene, respectively. The roughness of used reflector surface was measured to be ca. four times as big as that of a commercial mirror. However, their removal efficiencies are expected to be enhanced by increasing an light intensity resulting from lowering the roughness of used reflector coated on the improved photocatalytic reactor in the future.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.689-695
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• 2012

The friction factor in a rod bundle and the loss coefficient at a spacer grid were examined. As a test section, 25 smooth rods, 9.5 mm in diameter and 2000 mm in length, were prepared and installed in a $5{\times}5$ square array in a square channel. In this case, the P/D (Pitch-to-Diameter ratio) was 1.35. In this work, plain (i.e., no mixing vanes), split-vane, and hybrid-vane spacer grids were tested. In a bare rod bundle (i.e., no spacer grid), the measured friction factors were in good agreement with the previous correlations. Among the spacer grids tested, the hybrid-vane spacer grid presented the largest friction factor in the rod bundle and loss coefficient. This may be because of the flow pattern change induced by large relative plugging of the flow cross section and mixing vane geometry. At Re=$5{\times}10^5$, the predicted loss coefficients of plain, splitvane, and hybrid-vane spacer grids were approximately 0.79, 0.80, and 0.88, respectively.

• Archives of design research
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• v.17 no.1
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• pp.99-108
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• 2004

Metal tableware of korea had been used from former days along with own to rice bowl exclusive use, this metal tableware has our country characteristic identity from the country that do rice to chief food to unique thing. This by recent publication we individual and peculiar ours create may. Hab, Yonyu, Omok, Okbalri of modeling of our country metal rice bowl are 4 kinds greatly. First is that is all lid in our country's metal rice bowl by 3 greatly to cultural meaning that is filled in modeling. Second, it is that there is man and woman old and the young official business while divide man and woman old and the young in our country's metal rice bowl, third, that size changes by other rice bowl according as age increases point. And item that cause definite effect in figurative feature of metal rice bowl is [ Existence and nonexistence of hoof ], [ Oral narration department's shape ], [ Reverence of oral narration belonging / Ratio of Body's height ], and [ Reverence of oral narration belonging / Ratio about Body maximum ] of it 4 be. This research finds identity of our country's design and it is basic research about that is wished to graft together in several Land of Supreme Happiness illuminating in several angles with our country characteristic metal rice bowl.

• Journal of Welding and Joining
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• v.13 no.2
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• pp.12-24
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• 1995

Recently, more researches have been actively performed for the assessment of material degradation and residual-life of elevated temperature plant components, as some of domestic fossil power plants become older than 30 years. In this paper, results of on_site residual life assessment are reported for main steam pipes of Youngwol power station #2 which have operated since 1965. For critical weld locations such as butt welds branch welds, Y_sections and a T-section, replication technique and hardness measurement technique were employed for life_assessment. When cracks were detected by conventional NDT tests, crack growth life was calculated using a computer code. On the other hand, for matrix of pipes, residual life was quantitatively estimated by an analytic method and material degradation was estimated qualitatively using diameter measurement data and grain-boundary etching method. Also, direction in further improvement of on-site life assessment techniques are proposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.943-954
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• 2010

In this study, a radial inflow type turbine was applied and the outer diameter of the turbine rotor was 108 mm. The turbine blade on a circular plate disc was designed as an axial-type because its partial admission rate was 1.4-4.1%. The turbine consisted of three stages. The performance test has been conducted with various admission rates, tip clearances and nozzle flow angles. The turbine output power was measured on each stage. The turbine performance was obtained in a wide rotational speed range in order to compare its performance according to various operating conditions. The net specific output torque was also measured to compare its overall performance. Computational analysis was conducted for predicting turbine performance. The computed results were in good agreement with the experimental results.

• Journal of Sensor Science and Technology
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• v.4 no.3
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• pp.9-14
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• 1995

For the development of liquid density measuring sensor using the natural frequency of a pipe, its principle and construction method were described. The stainless steel pipe, which has length of 32 cm, inside diameter of 2.3 cm and outside diameter of 2.5 cm, was used for the sensor. The exciting coil and the photo sensor were used to excite and to pick-up it, and the feedback circuit was designed to continue its vibrating. The natural frequency was consistent with the result of the spectrum analysis. It had a linearity of 0.0027 % and a sensitivity of 0.032 % in liquid density range from $0.8\;g/cm^{3}$ to $1.4\;g/cm^{3}$ and its frequency variation ratio was 0.024 $%/^{\circ}C$ in temperature range from $10^{\circ}C$ to $35^{\circ}C$.