• 수산해양기술연구
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• 제34권2호
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• pp.144-158
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• 1998

In order to study basic information on the developed electro-magnetic compass, experiments were carried out on board M. S. KAYA at the pier of Dong Kuk Steel Mill in Pusan and the Korean southern sea using a three-axis magnetic sensor from Jan. 21, 1995 to Feb. 14, 1996. The obtained results were as follows : 1. The amount of old metal on the pier was about 27,290tons~57,440tons with an average of 40,560tons, the artificial local disturbance at the pier was min. 27.1$\mu$T, max. 66.5$\mu$T, ave. 433$\mu$T for the horizontal component and min. -27.0$\mu$T, max. 45.1$\mu$T, ave. 3.7$\mu$T for the vertical component. Its direction of horizontal component was 305$^{\circ}$ with the ship's head up bearing at 225$^{\circ}$. 2. The ship's magnetic distribution on the starboard side on berthing at the pier was 17.4$\mu$T for the horizontal component and -6.2$\mu$T for the vertical component. On the ship's port side, it was 19.8$\mu$T for the horizontal component and 4.1$\mu$T for the vertical component. On the ship's starboard side at sea, the ship's magnetic distribution was 19.2$\mu$T for the horizontal component and 3.2$\mu$T for the vertical component. On the ship's port side, the readings were 22.0$\mu$T for the horizontal component and -1.8$\mu$T for the vertical component. The directions of these readings were nearly starboard side. 3. On the pier, the secular change of the artificial local disturbance decreased 8.3$\mu$T from 61.0$\mu$T to 52.7$\mu$T for the horizontal component and decreased 7.1$\mu$T from 8.9$\mu$T M 1.8$\mu$T for the vertical component. On the starboard side from its berth, the ship, s magnetic distribution increased 2.6$\mu$T from 14.8$\mu$T to 17.4$\mu$T for the horizontal component and increased -0.1$\mu$T from -6.1$\mu$T to -6.2$\mu$T for the vertical component. On the ship's port side from its berth, it increased 7.1$\mu$T from 12.7$\mu$T to 19.8$\mu$T for the horizontal component and increased 10.2$\mu$T from -6.1$\mu$T to 4.1$\mu$T for the vertical component. 4. While at sea, on the ship's starboard side, the Secular change of the ship's magnetic distribution increased 3.9$\mu$T from 15.3$\mu$T to 19.2$\mu$T for the horizontal component and increased 2.0$\mu$T from -5.2$\mu$T to -3.2$\mu$T for the vertical component. On the port side, the changes increased 11.4$\mu$T from 10.6$\mu$T to 22.0$\mu$T for the horizontal component and increased 4.9$\mu$T from -6.7$\mu$T to -1.8$\mu$T for the vertical component. Upon berthing at the pier, the deviation of the secular change increased westerly 1 degree W~ 2.5$^{\circ}$ W from 3.5$^{\circ}$ W~ 5$^{\circ}$ W M 6W with the ship's head up bearing at 225$^{\circ}$. While at sea, these increased westerly 2$^{\circ}$ ~ 3$^{\circ}$ from the Northeast to the South and increased easterly 1$^{\circ}$ ~ 8$^{\circ}$ from the Southwest to the North. 5. While at port, within 1 mile between the ship and berth of the pier, as we approached the pier, the westerly deviation increased and when we departed the pier easterly deviation increased. When approaching the pier, the deviation was smaller than the deviation when the ship was departing from the pier. When approaching the bearing at 225$^{\circ}$ with the ship's head up bearing, the varies of deviation was smaller than the varies when the ship's head up bearing was departing from it.

• 한국수산과학회지
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• 제47권6호
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• pp.1055-1062
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• 2014

Hydroacoustic surveys were conducted for spatio-temporal distribution and size estimation of fish in the Yongdam reservoir, Korea, from April to July 2014. Acoustic data were collected along acoustic transects using a 120 kHz scientific echosounder. The received acoustic data were the in situ acoustic target strength (dB) and nautical area scattering coefficient ($m^2/mile^2$). Data on fish behavioral patterns and size were collected using a DIDSON acoustic camera at stationary stations. Fish were mainly distributed in the center channel and close to the outer Yongdam reservoir. Acoustic density of fish in the summer season were higher than in the spring season. The seasonal vertical distribution pattern of fish aggregations may be strongly related to the vertical temperature structure. The size distribution of fish obtained from an acoustic camera correlated well with the acoustic size of fish from an echosounder.

• Journal of Mechanical Science and Technology
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• 제17권8호
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• pp.1211-1218
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• 2003

The present study investigated two-phase flow distribution and phase separation of R-22 refrigerant through various types of branch tubes. The key experimental parameters were the orientation of inlet and branch tubes (horizontal and vertical), diameter ratio of branch tube to inlet tube (1 and 0.61), mass flux (200-500 kg/㎡s), and inlet quality (0.1-0.4). The predicted local pressure profile in the tube with junction was compared and generally agreed with the measured data. The local pressure profile within the pressure recovery region after the junction has to be carefully investigated for modeling the pressure drop through the branch. The equal flow distribution case can be found by adjusting the orientation of the inlet and branch tubes and the diameter ratio of the branch tube to the inlet tube. The T-junction with horizontal inlet and branch tubes showed the nearly equal phase distribution ratio. The quality at the branch tube varied from 0 to 1 as the orientation of the branch tube changed, while it varied within${\pm}$50% as the orientation of the inlet tube changed.

• 대한치과보철학회지
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• 제42권5호
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• pp.583-596
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• 2004

Statement of problem : Stress concentration on the neck bone affects the bone resorption, and finally the implant survival. Purpose: In order to examine the stress distribution on the neck bone and prosthesis abutment for implants, decreasing abutment sizes were used. Material and methods : Axisymmetric models were used to obtain the data required. These models were composed of 4mm implants with 3.4mm and 4mm abutments, 5mm implants with 3.4mm and 5mm abutments and 6mm implants with 3.4mm and 6mm abutments. All abutments were designed to received a 10mm high by 10mm diameter gold crown. Functional element analysis was used to obtain these results using data that consisted of 50 N vertical and 45 degree inclination forces. Results : 1. Changing the diameter of the abutment on the implant affects the effect of the inclination forces more than the effect of the vortical forces. 2. Changing the diameter of the abutment on the implant affect the effect of the inclination forces more than the effect of the vertical forces. 3. Experimentation showed that the larger diameter implants provided a decreased neck bone stress, whereas a larger diameter abutment provided a decrease marginal abutment stress. 4. Experimentation showed that the neck bone and abutment received more stress from inclination forces than vertical forces, Conclusions: By decreasing the size of the abutment on the implant we were able to diminishneck bone stress.

• 대한치과보철학회지
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• 제44권1호
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• pp.85-102
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• 2006

Statement of problem: Currently, there are some 20 different geometric variations in implant/abutment interface available. The geometry is important because it is one of the primary determinants of joint strength, joint stability, locational and rotational stability. Purpose: As the effects of the various implant-abutment connections and the prosthesis height variation on stress distribution are not yet examined this study is to focus on the different types of implant-abutment connection and the prosthesis height using three dimensional finite element analysis. Material and method. The models were constructed with ITI, 3i TG, Bicon, Frialit-2 fixtures and solid abutment, TG post, Bicon post, EstheticBase abutment respectively. And the super structures were constructed as mandibular second premolar shapes with 8.5 mm, 11 mm, 13.5 mm of crown height. In each model, 244 N of vertical load and 244 N of $30^{\circ}$ oblique load were placed on the central pit of an occlusal surface. von Mises stresses were recorded and compared in the crowns, abutments, fixtures. Results: 1. Under the oblique loading, von Mises stresses were larger in the crown, abutment, fixture compared to the vertical loading condition. 2. The stresses were increased proportionally to the crown height under oblique loading but showed little differences with three different crown heights under vertical loading. 3. In the crown, the highest stress areas were loading points under vertical loading, and the finish lines under oblique loading. 4. Under the oblique loading, the higher stresses were located in the fixture/abutment interface of the Bicon and Frialit-2 systems compared to the ITI and TG systems. Conclusions: The stress distribution patterns of each implant-abutment system had difference among them and adequate crown height/implant ratio was important to reduce the stresses around the implants.

• 한국지반공학회논문집
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• 제18권6호
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• pp.141-152
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• 2002

본 논문은 급경사의 강성사면에 인접한 역 T형 옹벽에 작용하는 상재하중에 의한 연직 토압분포에 관한 실험적 수치해석적 연구결과이다. 강성사면의 조도, 사면과 옹벽 사이의 거리, 중력수준을 변화시킨 원심모형실험을 실시하고 옹벽 뒷채움재에 토압계를 매설하여 연직토압을 측정하였다. 상재하중에 의한 연직토압 분포에 관한 실험 결과를 기존의 두가지의 한계평형 해석이론 및 수치해석 결과와 각각 비교 분석하였다. 정성교(1993, 1997)에 의하여 제시된 보완 사이로이론과 흙쐐기이론을 사용한 한계 평형 해석법을 사용하였으며 그 이론을 확장하여 옹벽 배면 뒷채움재에 작용하는 상재하중에 의한 연직토압분포에 대한 특별해를 구하였다. 수치해석에서는 쌍곡선모델의 흙의 구성관계식이 적용된 FLAC 프로그램을 사용하였다. 수치해석에 의한 토압분포 산정 결과 원심모형실험 결과와 대부분의 경우에서 서로 일치하는 반면에 흙쐐기이론에서는 사면과 옹벽의 거리가 가까운 경우에 한하여 비교적 일치하는 경향을 보였다.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1999년도 한국생물과학협회 학술발표대회
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• pp.89.1-89
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• 1999

No Abstract, See Full Text

• 한국지진공학회논문집
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• 제3권4호
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• pp.11-22
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• 1999

본 논문에서는 일반적으로 사용되고 있느 면진건축물의 내진설계기준에 대한 타당성을 검증하고 새로운 층지진하중 산정식을 제안하였다 UBC-91의 층지진하중 산정식은 충분한 안전성을 가지지 못하였으므로 94년에 개정이 되었다 그러나 개정된 산정식도 고정기초건축물과 유사한 층지진하중 산정식을 사용하였으므로 비경제성이 문제점으로 지적되고 있다 그러므로 제안된 식에서는 2자유도계 면진건축물과 고정기초건축물의 모드형상을 이용하여 안전성, 경제성 및 적용성을 만족시키도록 하였다. 제안된 층지진하중 산정식의 정확성 및 적용성을 검증하기 위하여 코멘트저항 골조형식과 전단변 구조형식의 구조물의 예제해석을 수행하였으며 동적해석의 경우와 근접한 결과를 얻었다.

• 환경위생공학
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• 제23권4호
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• pp.45-54
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• 2008

Our study indicates the zooplankton abundance with characteristics of water column and the vertical distribution in Lake Jinyang, South Korea. Seasonal changes of zooplankton community are determined by environmental parameters like water temperature, pH, dissolved oxygen, suspended solids and chlorophyll a. In lake Jinyang, this study showed that the zooplankton abundance in transition zone(St.1, St.2) was higher density than in lacustrine zone(St.3). Rotifers were dominant zooplankton and among them, Polyarthra spp., Keratella spp. and Nauplli(Copepoda) were common. But Cladoceran showed the low density. During survey period, zooplankton abundance with vertical distribution in surface layer(epilimnion) was higher than in bottom layer(hypolimninon). Zooplankton densities in Surface and middle layer showed positive relationship with water temperature and the densities in bottom layer(hypolimnion) showed positive relationship with chlorophyll a. Our assumption in spite of the short term study are supported by the facts that increase of temperature driven by climate change more maintains the thermocline duration by the summer temperature stratification. Thus the results suggest that the climate changes are an important source of changing zooplankton community feeding phytoplankton. So the zooplankton should be monitoring by the ecological management of Lake Jinyang to cope with climate changes like flood plain or drought.

• 아시안잔디학회지
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• 제11권2호
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• pp.89-95
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• 1997

Soil chemical properties were investigated to elucidate vertical movement of mineral nutrients in a fairway slope of 27 year-old golf course. Soil samples were taken at every 10cm depth to 4Ocm on 4 sites 20m apart each along two parallel lines 60m apart on the slope(15˚) in August. Accord-ing to the similarity of vertical distribution pattern they could be classified into 6 distinctive groups(magnesium, nitrate, phosphorus, ammonium, manganese and copper) and the slope tended to affect the vertical movement of minerals. The contents of Ca and Mg increased with depth while NO$_3$-N and Zn decreased and correlated positively. Soil pH showed significant positive correlation with depth, Ca and Mg. Phosphorus content was highest in 10~20cm depth and decreased resulting in relatively high content in 30~40cm depth of the bottom site of slope. Iron distribution pattern was similar to phosphorus. Potassium and $NH_4$showed various(irregular) patterns. Mn was highest in the deep layer at the lower sites of slope but it was reverse at the upper sites and negatively correlated with Fe. Cu content incresed with depth and heighest in 20~30cm depth. Electroconductivity showed significant positive correlation with $NO_3$-N. Magnesium, cal-cium and copper seem to be prone to defficiency due to fast leaching, and nitrate and phosphorus prone to excess problem. Preventive measures on acidification of surface soil should be taken.