• 대한수의학회지
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• 제40권4호
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• pp.665-670
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• 2000

The present study was undertaken to investigate the morphological characteristics of the suprachiasmatic nucleus (SCN) of the Korean native goat by cresyl violet stain. The SCN was located ventrolateral to the third ventricle and dorsal to the optic chiasm. This nucleus was showed carrot form in longitudinal section. Its size was 1.8 mm in length, 0.9 mm in maximum height and 1.6 mm in maximum width. In coronal sections, the SCN shaped very thin plate in rostral part, but it was changed to sweet-potato form in middle part, and ornamental jade form in caudal part. The size of SCN was larger in caudal part than in rostral part. The size of the neuron of SCN was about $10{\mu}m$ in diameter with round or oval shape. The boundary of SCN was not firmly defined in caudal part because the neurons were dispersed into the hypothalamic region. It is concluded that the SCN of the Korean native goat has a morphological characteristics.

• 수산해양기술연구
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• 제49권2호
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• pp.144-152
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• 2013

In an effort to find the optimum porous of Taewoo through the mathematical model 2 - dimensional tank water experiment among the approached to a problem related to ocean engineering, this study analyzed the porosity by dividing it into 9 cases. As the wave penetrates through the longitudinal porous of the Taewoo model, it was found that there is a wave energy loss because of the phenomenon of the separation of the porous due to the eddy. Looking into the general tendency based on the wave-height meter (probe) data, it was found that the shorter wavelength and higher frequency area, the more reflection coefficients increased, but in contrast, the longer wavelength and lower frequency area, the transmission coefficients showed the increasing trend and energy dissipation was in a similar way with reflection coefficients. In addition, it was found that the bigger the porosity was, the narrower distribution range of reflection coefficients was, and the more its average value decreased. On the other hand the transmission coefficients in direct opposition to reflection was found to show the wider range and the more gradual increase in the average value as porosity was the bigger around the average value. In contrast, energy dissipation rate was found to increase linearly as porosity increased the more around the porosity of 0.2518 but it decreased gradually around the peak point. Through the above results, it is judged that the porous of optimum in the longitudinal direction of the Taewoo model perforated plate was about 2.6cm because it was found that the porosity which produced the lowest reflection and transmission coefficient and the highest energy dissipation. As a result of comparing this to the case where there was no porosity at all, it showed the function of wave absorbing about 31.60%.

• KSBB Journal
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• 제20권3호
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• pp.244-249
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• 2005

Kromasil HR100-5CHI-TBB 칼럼을 사용하여 HPLC를 통한 비스테로이드 계통의 진통 및 소염제인 racemic ibuprofen의 분리특성을 연구하였다. 이동상의 조성비 변고에 따른 분리도 (resolution), 이론단수 (number o( theoretical plates), 이론단 높이 (HETP: Height Equivalent to a Theoretical Plate), 용량인자 (capacity factor)를 계산하고, 그 결과 정성분석 기준치 이상의 분리도를 갖고 분리시간을 단축할 수 있는 hexane /t-BME의 조성이 55 / 45일 때 $1\%$의 acetic acid를 첨가했을 때의 용매를 최적의 이동상으로 결정했다. 유속에 따른 칼럼의 효율을 비교하기 위한 실험을 통해 유속의 상승은 칼럼의 효율의 감소를 야기하고, 분리도를 감소시킴을 보였다. PIM (Pulsed Input Method)을 사용하여 분석한 결과 ibuprofen 의 농도가 증가할수록 Langmuir 등온흡착식을 따르는 비선형 거동을 보임을 증명하였고, 그 결과 등온흡착식을 결정하였다. 등온흡착식은 S-form과 R-form의 경우 각각 $C_{S,S}=\frac{1.178C_{M,S}}{1+0.019C_{M,S}},\;C_{S,R}=\frac{1.866C_{M,S}}{1+0.017C_{M,S}}$로 결정하였다.

• 한국항공우주학회지
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• 제33권4호
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• pp.35-40
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• 2005

압축하중을 받는 실린더형 구조물에 대한 보강방법으로는 스킨-스트링거, 격자보강 형상 등 여러 종류가 있다. 그 중 isogrid 형상은 정삼각형형태의 보강대가 반복되는 보강구조로서 여러 가지 조합하중 및 집중하중에 대한 대처능력이 우수한 보강구조이다.본 논문에서는 격자보강 구조 중 isogrid 구조에 대한 압축 좌굴시험 및 비선형 해석을 수행하였다. Isogrid 패널은 두께가 11.43 mm, 높이가 660 mm, 외경이 2.4 m이며 70도의 원호를 이루는 알루미늄합금 일체형 구조이다. 시편에 대한 압축 좌굴시험을 통하여 국부좌굴강도, 전체좌굴강도, 국부좌굴후의 거동 등을 확인하였다. 또한 MSC/MARC를 이용한 비선형 FEM 해석을 수행하여 구조시험 결과와 비교하였다. 해석 시에는 패널의 소성 가공 시 발생한 형상공차를 고려하였다. 시험결과와 해석결과는 좌굴하중 및 좌굴모드가 모두 비교적 일치하였다.

• 대한조선학회논문집
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• 제57권4호
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• pp.182-190
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• 2020

This study reports a series of drop impact tests performed to generate denting damages on stiffened plates and their residual ultimate strength tests under axial compression. The models were fabricated of general structural steel, and each model has six longitudinal stiffeners and two transverse frames. Among six fabricated models, four were damaged, and two were left intact for reference. To investigate the effects of collision velocity and impact location on the extent of damage, the drop height and the impact location were changed in each impact test. After performing the collision tests, the ultimate axial compression tests were conducted to investigate the residual strengths of the damaged stiffened plates. Finite element analyses were also carried out using a commercial package Abaqus/Explicit. The material properties obtained from a quasi-static tensile tests were used, and the strain-rate sensitivity was considered. After importing the collision simulation results, the ultimate strength calculations were carried out and their results were compared with the test data for the validation of the finite element analysis method.

• Journal of Welding and Joining
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• 제24권1호
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• pp.56-63
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• 2006

The characteristics of $CO_2$ or Nd:YAG laser welded 600MPa ade TRIP steel was investigated. He or Ar gas was used as a shield gas in case of $CO_2$ laser welding, but the shield gas was not used in case of Nd:YAG laser welding. Bead on plate welding was performed with various welding conditions. Defects in the joints of both welding type occurred at 1.8m/min but were not observed over the welding speed of 2.1m/min in case of Nd:YAG laser welding. However, porosity occurred in $CO_2$ laser welding and the tendency of decreasing with the increase of welding speed. The hardness was the highest at heat affected zone near fusion zone as well as at the fusion zone and decreased on approaching the base metal. In a perpendicular tensile test to the weld line, all specimens that have been welded at optimum conditions were fractured at the base metal, and the tensile properties showed the rather higher than those of raw material. In a parallel tensile test, the strength of the joints was higher than that of the base metal. Elongation was found to be lower than that of the raw material. Forming height by Erichsen test and elongation were deeply related with the ratio of base metal/weld metal and the maximum hardness of the weld metal. Also porosity induced to decrease the strength and the elongation. The maximum formability was recorded at approximately 80% as compared with that of the raw material with the optimum condition.

• 대한의용생체공학회:의공학회지
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• 제32권3호
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• pp.230-236
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• 2011

The aim of this study was to investigate the alteration of lumbar spine and trunk postures on different load-carrying types and amounts under static loading. Two load-carrying types(unilateral carrying: UC vs. bilateral carrying: BC) and four different loads(0, 5, 10, and 15 kg) were randomly tested in this study. Carrying a heavy bag would affect human body posture, specifically lumbar spine curvature, which is considered as one of sources of back problems. Previous studies have not paid attention to the approach of the multisegment model of the lumbar spine and trunk. This study separated two compartments of trunk segment(the lumbar and thorax) in the analysis. The multisegment model of the lumbar spine in addition to Helen-Hayes marker set was used. Eight motion analysis cameras and a force plate were utilized. Ten male subjects(mean mass, $70.6{\pm}3.97$ kg; mean height, $178{\pm}4.18$ m) having no musculoskeletal disease participated in this study. We analyzed trunk angles in three anatomical planes and the spinal curvature in sagittal and frontal planes. Increased loading in both UC and BC significantly resulted in increases in trunk forward lean but only UC induced increases in trunk lateral lean. In addition, increased loading in BC produced flatten lumbar curvature in sagittal plane. As far as coupling motion, subjects tended to use axial rotation of the lumbar spine in transverse plane in response to increased UC loading. Finally, it is concluded that the increased static loading in UC rather than in BC tends to causes combined alterations of the spinal postures(sagittal and transverse planes together), which would be vulnerable to improper mechanical stresses on the spine.

• 대한인간공학회지
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• 제25권4호
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• pp.115-119
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• 2006

To investigate the effects of independent suspension technology(IST) of hiking boot on the stability and load of foot, eight participants performed medial and lateral drop landing from 33.4cm height and 85cm distance to uneven surface while wearing normal & IST hiking boots. For the stability of foot during the drop landing, the balance angle & suspension angle and rearfoot angle was analyzed using high-speed video analysis. Also kinetic analysis using the force plate and insole pressure measurement was conducted to analyze vertical & breaking ground reaction force and pressure distribution. Not only the balance angle & suspension angle but also rearfoot angle was improved with IST boots for lateral drop landing. These results indicate the IST boots may have the suspension function which keeps the foot to be stable during landing. However the IST boots did not show any effect for medial landing. This might be related to the hardness of medial part of outsole. Therefore the softer outsole of medial part could be recommended. Furthermore the impact force & breaking force and insole pressure were reduced with IST boot. These results means that IST boot has not only cushioning effect but also good grip effect. Therefore the hiking boots applied the independent suspension function may help to reduce fatigue and prevent injury such as ankle sprain in hiking on uneven surface.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.77-80
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• 2008

국내 내진설계가 도입되지 않은 1992년 이전에 설계 시공된 교량과 교각의 경우 소성힌지구간 에 충분한 횡구속이 되지 않은 상태에서 주철근 겹침 이음을 가지고 있는 것이 대부분이다. 이 연구는 철근콘크리트 교각의 내진성능에 영향을 미치고 있는 변수들로서 소성힌지구간의 주철근 겹침이음 및 두께를 달리한 강판보강을 선택하여 준정적(Quasi-Static)실험 방법에 의하여 철근콘크리트 교각의 내진 성능을 평가 하였다. 특히 기존의 강판 보강 공법은 강판 내부를 모르타르로 그라우팅하였으나, 이 연구에서는 보강된 강판내부를 그라우팅하지 않았다. 이를 위하여 형상비 3.5의 철근콘크리트 기둥 시험체 (지름 400mm, 높이 1600mm) 4개를 제작하였다. 실험 변수는 주철근 겹침이음 0%, 50%, 보강 강판 두께 2종(1mm, 2mm)을 선택하였다.

• 한국산림과학회지
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• 제77권3호
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• pp.283-293
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• 1988

산공재(散孔材)인 왕버들(Salix glandulosa Seemenn)과 환공재(環孔材)인 굴참나무(Quercus variabilis BI.)의 뿌리, 줄기 및 가지에 있어서 2기(二期) 목부조직(木部組織)을 해부학적(解剖學的)으로 비교관찰(比較觀察)하였다. 굴참나무의 뿌리의 도관분포(導管分布)는 줄기와 달리 산공형(散孔型)이다. 뿌리의 연륜(年輪) 경계(境界)는 양(兩) 수종(樹種)에서 대체(大體)로 불분명(不分明)하다. 도관요소(導管要素) 및 대섬유(大纖維)는 뿌리에서 제일 길고, 가지에서 가장 짧다. 또한 도관(導管)의 직경(直徑)은 뿌리, 줄기, 가지의 순(順)으로 좁아진다. 횡단면상(橫斷面上)에서 도관(導管)의 단위면적당(單位面積當) 분포수(分布數)는 가지에서 제일 많고 뿌리에서 가장 적다. 도관요소(導管要素)의 천공(穿孔)은 두 수종(樹種) 모두 단천공(單穿孔)이고, 천공판(穿孔板)의 경사각(傾斜角)은 뿌리, 줄기, 가지의 순(順)으로 작아진다. 접선단면상(接線斷面上)에서 방사조직(放射組織)은 뿌리가 줄기나 가지에 비(比)해 높은 반면(反面), 단위면적당(單位面積當) 분포수(分布數)는 뿌리에서 줄기나 가지에 비(比)해 적다.