• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.379-388
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• 2002

For the success of dental implant, accurate radiographic evaluation is prerequisite for planning the location of the osseointegrated implants and avoiding injury to vital structures. CT/MPR(computed tomography/multiplanar reformation) shows improved visualization of inferior alveolar canal. In order to obtain cross-sectional images parallel to the teeth, the occlusal plane is used to orientate for the axial plane. If the direction of axial plane is not parallel to the occlusal plane, the reformatted cross-sectional scans will be oblique to the planned fixture direction and will not show the actual dimension of the planned fixture's location. If the available bone height which measured in the cross-sectional view is much greater than the actual available bone height, penetration of canal may occur. The aim of this study is to assess the effect of the axial plane to measurement of available bone height for dental implant in computed tomography of the mandible. 40 patients who had made radiographic stents and had taken CT were selected. The sites that were included in the study were 45 molar regions. In the central panoramic scan, the length from alveolar crest to superior border of inferior alveolar canal(available bone height, ABH) was measured in direction of reformatted cross-sectional plane(uncorrected ABH). Then, length from alveolar crest to superior border of canal was measured in direction of stent(corrected ABH). The angle between uncorrected ABH and corrected ABH was measured. From each ABH, available fixture length was decided by $Br{{\aa}}nemark$ system. The results were following ; the difference between two ABHs was statistically significant in both first and second molar(p< 0.01). The percentage of difference more than 1 mm was 8.7% in first molar and 15.5% in second molar. The percentage of difference more than 2 mm was 2.0% in first molar and 6.6% in second molar. The maximum value of difference was 2.5 mm in first molar and 2.2 mm in second molar. The correlations between difference of 2 ABHs and angle was positive correlations in both first and second molar. The correlation coefficient was 0.534 in first molar and 0.728 in second molar. The second molar has a stronger positive correlation. The percentage of disagreement between 2 fixture lengths from two ABHs was 24.4% in first molar and 28.9% in second molar.

• Korean Journal of Agricultural Science
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• v.27 no.1
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• pp.48-53
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• 2000

The various errors existing in a weight measurement system in most automatic egg sorting system available in Korean poultry farms have caused a large amount of economic losses to the egg producers. The object of this study was an importance of egg measurement system by changing both the number and the arrangements of load cells to reduce measuring errors. The results obtained were summarized as follow : 1. Four arrangements of load cells were selected as follows : layout I : Conventional one load cell method layout II : One load cell located as egg moving direction layout III : Two load cells located facing each other layout IV : Two load cells located as parallel with egg moving direction 2. The results of egg weight measurement according to four arrangements (Layout I, II, III, IV) showed that the average errors were 1.1218g, 0.5953g, 0.7786g, 0.2793g respectively. This indicated that the Layout IV (measuring by 2 load cells located parallel with the egg moving direction) caused the lowest average error and the best in precision. 3. The average vibration of axis X, y, Z were resulted as $5.1937{\times}10^{-3}G$, $9.3604{\times}10^{-3}G$, and $16.8657{\times}10^{-3}G$ respectively when sorting large sized egg. This indicated that the vibration of axis-Z was relatively higher than those of axis-X, and axis-Y.

• Journal of the korean veterinary medical association
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• v.20 no.1
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• pp.49-61
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• 1984

The purpose of the experiment was to clarify morphologically normal growth pattern of male reproductive organ in heavy meat breed rooster. The observations were composed of normal growth in weight of whole body, comb, testis and pituitary glands and of hi

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.9
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• pp.687-697
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• 2006

The air and water flow distribution are experimentally studied for a heat exchanger composed of round headers and 10 flat tubes. The effects of tube protrusion depth as well as mass flux, and quality are investigated, and the results are compared with the previous 30 channel results. The flow at the header inlet is annular. For the downward flow configuration, the water flow distribution is significantly affected by the tube protrusion depth. For flush-mounted geometry, significant portion of the water flows through frontal part of the header. As the protrusion depth increases, more water is forced to the rear part of the header. The effect of mass flux or quality is qualitatively the same as that of the protrusion depth. Increase of the mass flux or quality forces the water to rear part of the header. For the upward flow configuration, different from the downward configuration, significant portion of the water flows through the rear part of the header. The effect of the protrusion depth is the same as that of the downward flow. As the protrusion depth increases, more water is forced to the rear part of the header. However, the effect of mass flux or quality is opposite to the downward flow case. As the mass flux or quality increases, more water flows through the frontal part of the header. Compared with the previous thirty channel configuration, the present ten channel configuration yields better flow distribution. Possible explanation is provided from the flow visualization results.

• Korean Journal of Plant Tissue Culture
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• v.27 no.6
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• pp.429-434
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• 2000

Isolated protoplasts from ginseng (Panax ginseng C. A. Meyer) callus tissue were cultured in modified MS media supplemented with various concentrations of dimethylsulfoxide (DMSO). The cell wall regeneration rate and cell division efficiency of the protoplasts were increased significantly by 1% DMSO treatment. However, there was no difference in the viability of protoplasts between the DMSO treatment and non-treatment. Transmission electron microscopy revealed that the microtubules were oriented in parallel manner to the plasmalemma after 3 days of culture in medium with 1% DMSO. Further, interconnected cellulose microfibrils were observed on the outer surface of the 3-day-cultured protoplasts by scanning electron microscopy These structures shown by electron microscopy were not observed in protoplasts cultured on DMSO-free media. This studies indicates that DMSO supplemented in culture media seemed to stimulate the cell wall regeneration and cell divisions of protoplasts by forming microtubule organizing centers (MTOC).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.9
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• pp.1249-1259
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• 2002

The present study investigates the convective heat/mass transfer inside a cooling passage of rotating gas-turbine blades. The rotating duct has various configurations made of ribs with 70。 attack angle, which are attached on leading and trailing surfaces. A naphthalene sublimation technique is employed to determine detailed local heat transfer coefficients using the heat and mass transfer analogy. The present experiments employ two-surface heating conditions in the rotating duct because the surfaces, exposed to hot gas stream, are pressure and suction side surfaces in the middle passages of an actual gas-turbine blade. In the stationary conditions, the parallel rib arrangement presents higher heat/mass transfer characteristics in the first pass, however, these characteristics disappear in the second pass due to the turning effects. In the rotating conditions, the cross rib present less heat/mass transfer discrepancy between the leading and the trailing surfaces in the first pass. In the second pass, the heat/mass transfer characteristics are much more complex due to the combined effects of the angled ribs, the sharp fuming and the rotation.

• Journal of Educational Research in Mathematics
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• v.23 no.1
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• pp.53-74
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• 2013

The purpose of this paper is to analyze how mathematically gifted middle school students find out the necessary and sufficient condition for a certain hyperbolic line to be parallel to a given hyperbolic line in Non-Euclidean disc model (Poincar$\acute{e}$ disc model) using the Geometer's Sketchpad. We also investigated their characteristic of mathematical thinking and analyze how they express what they had observed while they did mental experiments in the Poincar$\acute{e}$ disc using computer-aided construction tools, measurement tools and inductive reasoning.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.45-45
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• 2008

$SrTiO_3$/Organic composites 는 Inorganic/organic 복합재료로, 유전 특성이 우수하고, 저온하여 제조단가의 감소가 가능하다. 이를 바탕으로 $SrTiO_3$/Organic composites 복합재를 이용한 가능성을 확인하기 위해 Multilayer 구조의 Coupler를 설계, 제작 후 특성을 분석하였다. Coupler 는 RF signal을 분기하기 위한 목적으로 평행한 한 쌍의 Conductor line 구조를 가진다. 2개의 Line 의 길이를 특정주파수 $f_0$의 wavelength $\lambda$/4 로 설계하여 서로 근접 시켰을 때 $f_0$를 중심으로 RF 신호 분기 현상이 나타난다. 보다 넓은 대역에 걸쳐서 신호분기를 하기 위해서는 두 line 간의 간격을 좁혀 Signal coupling 효과를 증가 시킨다. single layer conductor 구조에서는 물리적인 한계가 있으므로, multilayer 구조를 사용하면 보다 넓은 대역의 Coupled line coupler 로서 기능하게 된다.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.519-524
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• 2008

In the present study, the air-side heat transfer and pressure drop characteristics of the fin-tube and PF heat exchangers have been experimentally investigated under the cooling standard condition. Fin type of PF heat exchanger is a triangler and squarer form. The experimental data of the slit fin-tube and two kinds of PF heat exchangers are measured using the air-enthalpy calorimeter and the constant temperature water bath. As the inlet air velocity increases, the heat transfer rate and pressure drop of the heat exchanger increased. The heat transfer rate and pressure drop of PF-2 heat exchanger of the squarer fin is larger than that of PF-1 heat exchanger of the triangler fin. As the inlet air temperature increases, the heat transfer rate decreases and the pressure drop is nearly uniform.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.1
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• pp.75-82
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• 1999

일반 해양 구조물이나 해저면에 설치되는 해저 관로는 외력에 의한 변형이 발생된다. 구조물 형상이 복잡하거나, 구성 요소의 개수가 많을 경우 응력해석 시 많은 초기값이 필요하고 해석 시간 또는 장 시간 소요된다. 해양 구조물에 작용하는 대표적인 외력은 파도, 조류, 바람이고 이런 외력은 구조물의 사용 기간(operation life)동안 계속적으로 작용하기 때문에 구조물의 변형율은 항상 허용치 안에서 발생되도록 설계되어야 한다. 허용 변형은 탄성범위 내에 존재해야 하며, 비교적 큰 변형을 일으키는 구조물이나 해저파이프라인의 응력해석을 수치적으로 접근하는 방법을 고찰하였다. 평행상태의 하중 벡터값만 직각 좌표계에서 인트린직(intrinsic) 좌료로 변환시킬 때 변형이 발생함으로, 본 논문에서 소개하는 이차 요소(quadratic element)방법을 사용할 경우 수치해석 시 많은 장점이 있다는 것을 보여준다. 본 방법을 도입함으로써 비교적 큰 변형이 발생되는 구조물 해석 시 일반 수치해석 방법과 그 결과는 같으나 해석 시간을 단축시킬 수 있다는 장점이 있다. 응력 해석 시 국부 강도 행열(element stiffness matrix)은 방향과 무관하며 이차요소 방법을 사용하여 각 요소 벡터를 발생시켰다. 해저관로 일점 상승 시 관로에 작용하는 변형과 상승력에 따른 휨 모멘트를 산출하여 일반적으로 사용되는 선형이론과 비교하였다.