• Structural Engineering and Mechanics
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• 제27권2호
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• pp.135-148
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• 2007

A new finite shear wall element model and a method for calculation of 3D multi-storied only shear walled or shear walled - framed structures using finite shear wall elements assumed ideal elasto - plastic material are developed. The collapse load of the system subjected to factored constant gravity loads and proportionally increasing lateral loads is calculated with a method of load increments. The shape functions over the element are determined as a cubic variation along the story height and a linear variation in horizontal direction because of the rigid behavior of the floor slab. In case shear walls are chosen as only one element in every floor, correct solutions are obtained by using this developed element. Because of the rigid behavior of the floor slabs, the number of unknowns are reduced substantially. While in framed structures, classical plastic hinge hypothesis is used, in nodes of shear wall elements when vertical deformation parameter is exceeded ${\varepsilon}_e$, this node is accepted as a plastic node. While the system is calculated with matrix displacement method, for determination of collapse safety, plastic displacements and plastic deformations are taken as additional unknowns. Rows and columns are added to the system stiffness matrix for additional unknowns.

• 한국운동역학회지
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• 제15권3호
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• pp.133-142
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• 2005

The purpose of this study was to compare of the kinematic variables from takeoff preparation to takeoff used by long jumpers who recorded over 8meters in 2002 Busan Asian Game and 2003 Daegu Universiade and 2001 national championship. The kinematic characteristics from the last three stride to takeoff at the takeoff board were analyzed such as velocities, heights and angles. The conclusion were as follows; In order to record over 8meters the national long jumpers should have under 5cm height variation at the penultimate stride of the run-up. In the approach phase the horizontal velocity of the jumpers should reach to 10m/s in touchdown at takeoff board The vertical velocity must have 3.75m/s simultaneously in order to record 8meters. The jumpers need to continue talent of the horizontal velocity in touchdown at takeoff board and require jumping power of the takeoff leg at takeoff board The appropriate body variation range ratio between takeoff and touchdown should be 1.2 vs 1 and the trunk angle at touch down on the board should be close to the erect posture for higher body flight.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.227-231
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• 2004

Technological advance in information technology has sparked the necessity of small form factor (SFF) optical disk for mobile devices. Small form factor optical disk is highly anticipated to be a next generation storage device because it can be used for a cost-effective way compared with solid state memory. For the application to the 5 mm height small-form-factor optical disk drive, we have presented an optical flying head and swing arm actuator. In this study, we propose a small 1-axis actuator for compensating ficus error and SA due to the variation of cover-layer thickness in the cover-layered small optical disk. The main design issues of the 1-axis actuator are the realization of compact structure and the new support structure of the actuator: Finally, the compensating principle and performance of the 1-axis actuator will be explained.

• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.633-643
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• 2019

Growth characteristics [stem diameter (D), tree height (H)] and wood properties [Pilodyn penetration (P) and stress-wave velocity (SWV)] were measured for 65 families of 6-year-old Acacia mangium trees planted in Indonesia, in order to characterize their variation in D, H, P, and SWV. Therefore, the correlations between the measured characteristics were also determined, and their significant differences observed. Furthermore, their low to moderate values of narrow-sense heritability was obtained, and the results indicated the characteristics to be genetically controlled in A. mangium. In addition, highly significant positive correlations were observed among the growth characteristics, suggesting a close relationship, while there was no significant association between the growth characteristics and P, as well as SWV, indicating their independent. Therefore, these results demonstrate a potential for the improvement of both growth and wood properties of A. mangium trees, using the appropriate breeding programs. In addition, 18 families showed good performance in D and SWV, signifying their positive prospect of being considered as plus trees for the next generation breeding cycles.

• 한국기계가공학회지
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• 제20권7호
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• pp.15-24
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• 2021

In this paper, to analyze the types of surface morphology error according to factors that cause machining error, the experiments were conducted in the ultra-precision diamond machine using a diamond tool. The factors causing machining error were classified into the pressure variation of compressed air, external shock, tool errors, machining conditions (rotational speed and feed rate), tool wear, and vibration. The pressure variation of compressed air causes a form accuracy error with waviness. An external shock causes a ring-shaped surface defect. The installed diamond tool for machining often has height error, feed-direction position error, and radius size error. The types of form accuracy error according to the tool's errors were analyzed by CAD simulation. The surface roughness is dependent on the tool radius, rotational speed, and feed rate. It was confirmed that the surface roughness was significantly affected by tool wear and vibration, and the surface roughness of Rz 0.0105 ㎛ was achieved.

• Geomechanics and Engineering
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• 제31권4호
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• pp.375-384
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• 2022

The variation of the undrained shear strength (c_u) is an important consideration for assessing slope stability in engineering practice. Previous studies focused on the three-dimensional (3D) stability of slopes in normally consolidated clays generally assume the undrained shear strength increases linearly with depth but does not vary in the horizontal direction. To assess the 3D stability of slopes with spatially varying undrained shear strength, the kinematic approach of limit analysis was adopted to obtain the upper bound solution to the stability number based on a modified failure mechanism. Three types failure mechanism: the toe failure, face failure and below-toe failure were considered. A serious of charts was then presented to illustrate the effect of key parameters on the slope stability and failure geometry. It was found that the stability and failure geometry of slopes are significantly influenced by the gradient of c_u in the depth direction. The influence of c_u profile inclination on the slope stability was found to be pronounced when the increasing gradient of c_u in the depth direction is large. Slopes with larger width-to-height ratio B/H are more sensitive to the variation of c_u profile inclination.

• Asian-Australasian Journal of Animal Sciences
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• 제13권10호
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• pp.1353-1358
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• 2000

The three-way rotational crossing experiment has been conducted to evaluate heterosis effects on jumping height and body weight. Yonakuni wild mice (Y) and two genetic groups of $CF_{{\sharp}1}$ (C) and C3H/HeNCrj (H) laboratory mice were used as materials. Reciprocal rotational crossing was made by crossing C male${\times}$Y female and Y male${\times}$C female to produce basic group designated $G_0$ and ${G_0}^{\prime}$, respectively. The females of the $G_0$ and ${G_0}^{\prime}$ were mated to the H sire to produce second generation ($G_1$ and ${G_1}^{\prime}$), and at the following generation the replacement females were mated to Y or C sire according to the basic group to produce $G_2$ to $G_3$ and ${G_2}^{\prime}$ to ${G_3}^{\prime}$. Individual jumping height data at Wk6 and body weight data at 1 (Wk1), 3 (Wk3), 6 (Wk6) and 10 (Wk10) weeks of age were analyzed. The results showed that effects of genetic group, sex and interaction of genetic group by sex were significant (p<0.01) for jumping height. For males, 55.34%~79.17% and 54.46%~78.29% of heterosis were reached at $G_1$ to $G_3$ and ${G_1}^{\prime}$ to ${G_3}^{\prime}$, respectively. While for females at $G_1$ to $G_3$ and at ${G_1}^{\prime}$ to ${G_3}^{\prime}$, heterosis effects were 61.53%~80.42% and 47.79%~85.86%, respectively. For body weight, genetic group was a significant source of variation at all ages studied. Sex effect was significant at Wk3, Wk6 and Wk10, and interaction between genetic group and sex was significant at Wk6 and Wk10 (p<0.01). C sires resulted in the highest body weight of offspring, while H sires were the intermediate and Y sires were the lightest. The significant positive and negative heterosis effects for body weight were exhibited. Crossing involved the Y sires in addition to smaller maternal effects of Y dams tended to result in small heterosis.

• 한국패류학회지
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• 제17권2호
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• pp.71-78
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• 2001

1995년 4월부터 1996년 3월까지 충청남도 보령시 연안에 서식하는 키조개를 총 701마리 채집하여 성장을 조사하였다. 1. 키조개의 패각에 나타나는 윤문은 년1회 형성되며 주 윤문형성시기는 6월에서 7월로 조사되었다. 2. 초륜 형성기간은 12개월(만 1년)로 나타났다. 3. 각고 (SH)와 총중량 (TW)간의 관계는 TW=5.906$\times$$10^{-3}$S $H^{3.3844}$이었으며, 각장 (SL)과 각고(SH)간의 관계는SL=0.5277SH+0.0934이고, 각장 (SL)과 각폭(SW)간의 관계는 SW=0.2681SH-1.3757였다. 4. 연령(t)에 대한 각고 (SH)와 총중량 (TW)의 Bertalanffy 성장식은 SHt=30.99(1-e-$^{0.321}$2(t+0.9653)/이고 (Fig.11) TWt=657.94(1-e-$^{0.321}$2(t+0.9653/)$^{3.3844}$(Fig. 12)였다.)였다.

• 한국패류학회지
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• 제19권2호
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• pp.125-132
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• 2003

1999년 1월부터 12월까지 매월 충남 보령연안에 서식하는 살조개 총 2,591 개체를 채집하여 연령과 성장에 관하여 조사하였다. 살조개의 패각에 나타나는 윤문은 연 1회 형성되었으며, 윤문형성 시기는 2-3월 중인 것으로 조사되었다. 각고(SH)에 대한 각장 (SL), 각폭 (SW) 및 총중량 (TW) 사이의 상대성장 관계는 각각 SL = 1.1067 SH + 1.778, SW = 0.6758 SH - 0.9824, TW = 0.0007 SH$^{2.8919}$이었고, 연령 (t) 에 대한 각고와 총중량으로부터 구한 von Bertalanffy 성장식은 SH$_t$ = 81.546(1-e$^{-0.176(t+0.381)}$), $_t$ = 81.546(1-e$^{-0.176(t+0.381)}$)이었다.

• 한국산림과학회지
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• 제108권4호
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• pp.592-599
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• 2019

본 연구는 수간재적과 상관관계가 높은 흉고직경과 수고를 독립변수로 하여 우리나라 일본잎갈나무의 수간재적 추정식을 개발하고자 하였다. 전국의 분포하고 있는 일본잎갈나무를 총 2,840본의 표준목을 벌채하여 수간고별 직경과 수간석해 자료를 수집하여 생장특성을 조사하였다. 6개의 수간재적모델의 적합도 검정을 위하여 적합도지수, 편차, 평균절대편차, 변이계수를 이용하여 모델의 적합성을 판단하였다. 최종 선정된 모델은 흉고직경만을 이용한 Model 1(V=a+bDBH²), 흉고직경과 수고를 이용한 Model 4(V=a+bDBH²H)가 최적의 모델로 선정되었다. 비선형회귀분석을 통한 모델의 절편과 기울기계수인 a, b는 0.05수준에서 통계적으로 유의한 값을 보였다. 적합도지수는 94%~99%로 나타났고, 편차는 두 모델이 0에 근접하였으며, 평균절대편차는 0.01~0.05, 변이계수는 5.97~14.43으로 높은 적합도를 보였다. 본 연구에서 제시된 수간재적모델을 이용하여 현장에서 흉고직경 또는 흉고직경과 수고를 측정한 후 바로 재적을 추정할 수 있으며, 산림경영에 필요한 기초 정보를 제공해 줄 것이다.