• Journal of the Korean Wood Science and Technology
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• 제51권6호
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• pp.493-508
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• 2023

Round timber materials of 600 mm length, cut from large-cross-section round timber of red pine (Pinus densiflora S. et Z.) of 450 mm width and 4.2 m length, were prepared as the target of kiln drying in this study. After treating the target materials through end sealing (ES), end sealing - kerfing (ES-K), lateral sealing - end sealing - boring (LS-ES-B), or lateral sealing - partial end sealing (LS-PES), the effects of the treatment on the incidence of drying defects were determined. The target materials with exposed lateral surface and sealed cross surface were steamed at the initial temperature of 65℃ above the official pest control temperature of 56℃, followed by kiln drying toward the final temperature of 75℃. The target materials with sealed lateral surfaces, on the other hand, were dried at the initial temperature of 90℃ at almost the maximum temperature of conventional kiln drying, as there is no risk of early check formation caused by surface moisture evaporation. The final temperature was set at approximately 100℃. The drying time, taken for the target materials with initial moisture content of 70%-80% to reach the target moisture content of 19%, varied across treatment conditions. The measured drying time was 1,146 hours (approximately 48 days) for the timber with sealed cross surface and 745 hours (approximately 31 days) for the timber with sealed lateral surface, until the moisture content reached the target level. The formation of surface checks could not be prevented in the control and ES groups, but a definite preventive effect was obtained for the LS-ES-B and LS-PES groups.

• PNF and Movement
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• 제8권3호
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• pp.39-47
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• 2010

Purpose : The purpose of this study was to investigate the correlations between clinical balance scales and Balance Performance Monitor parameters in patient with adolescent idiopathic scoliosis (AIS). Methods : Twenty AIS subjects (age, $14.26{\pm}1.93yrs$; height, $160.56{\pm}7.98cm$; weight, $47.54{\pm}6.94kg$)were participated in this study. Postural sway(mean balance, sway angle, sway area, sway path, maximal sway velocity) were were evaluated by balance performance monitor. Measurements for clinical balance scales were Functional reach test (both side), the Lateral reach test (both side) and One leg standing test (both legs). Results : The results were as follows. There were positive strong correlation between major curve direction and left-right sway angle, sway path, maximal sway velocity. There were negative strong correlation between the functional reach and left-right sway angle, sway area, sway path, maximal sway velocity. And the lateral reach were also showed negative strong correlation parameters of balance performance monitor. One leg standing were negatively correlated with left-right sway angle, sway path, maximal sway velocity. Conclusion : The clinical balance scales will be useful tools for balance measurements, and basic tools for clinical setting for patient with AIS.

• 자원환경지질
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• 제40권3호
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• pp.319-330
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• 2007

청송 무포산응회암은 경상분지 북동부 화산암류에서 하나의 냉각단위로 구별되는 층서단위이다. 이 응회암은 그 입도에 의하면 대부분 응회암에 속하고 구성원에 의하면 파리질 응회암에 속한다. 대부분 부석과 샤드가 일정하게 배열되고 심하게 편평화되어 용결엽리를 발달시키며 여러 가지 흐름지시자를 보여준다. 무포산응회암에서 부석 정향배열에 의한 유상선구조로부터 이동 패턴, 암편과 부석의 와상배열, 용결엽리의 비대칭 유상습곡 등의 흐름 지시자, 암편과 부석의 최대입경의 측방점이, 그리고 구성원 함량의 측방점이에 의하면 이 응회암을 집적시킨 화쇄류는 남동부에서 공급되었던 것으로 해석된다.

• 제어로봇시스템학회논문지
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• 제21권3호
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• pp.224-232
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• 2015

In order to develop an active safety system which avoids or mitigates collisions with preceding vehicles such as autonomous emergency braking (AEB), accurate state estimation of the nearby vehicles is very important. In this paper, an algorithm is proposed using 3 dynamic models to better estimate the state of a vehicle which has various dynamic patterns in both longitudinal and lateral direction. In particular, the proposed algorithm is based on the Interacting Multiple Model (IMM) method which employs three different dynamic models, in cruise mode, lateral maneuver mode and longitudinal maneuver mode. In addition, a Probabilistic Data Association Filter (PDAF) is utilized as a data association algorithm which can improve the reliability of the measurement under a clutter environment. In order to verify the performance of the proposed method, it is simulated in comparison with a Kalman filter method which employs a single dynamic model. Finally, the proposed method is validated using radar data obtained from the field test in the proving ground.

• 제어로봇시스템학회논문지
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• 제21권3호
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• pp.179-186
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• 2015

In this paper, a novel lateral control system is proposed for the purpose of improving lane keeping performance which is independent from GPS signals. Lane keeping is a key function for the realization of unmanned driving systems. In order to obtain this objective, a vision sensor based real-time lane detection scheme is developed. Furthermore, we employ a data fusion along with a real-time steering angle of the test vehicle to improve its lane keeping performance. The fused direction data can be obtained by an IMU sensor and vision sensor. The performance of the proposed system was verified by computer simulations along with field tests using MOHAVE, a commercial vehicle from Kia Motors of Korea.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.284-291
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• 2005

A RC column-bent pier represents one of the most popular piers used in highway bridges. Seismic performance of reinforced concrete (RC) column-bent piers under bidirectional seismic loadings was experimentally investigated. Six column bent-piers were constructed with two circular supporting columns which were made in 400mm diameter and 2,000mm height. Test parameters are different transverse reinforcement and loading pattern. These piers were tested under lateral load reversals with the axial load of $0.1f_{ck}A_g$. Three specimens were subjected to bidirectional lateral load cycles which consisted of two main longitudinal loads and two sub transverse loads in one load cycle. Other three specimens were loaded in the opposite way. Test results indicated that lateral strength and ductility of the latter three specimens were generally bigger than those of the former three specimens. Plastic hinges were formed with the spall of cover concrete and the fracture of the longitudinal reinforcing steels in the bottom plastic hinge of two supporting columns for the former three specimens. Similar behavior was observed in the top and bottom parts of two supporting columns for the latter three specimens.

• 대한전자공학회논문지SD
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• 제45권10호
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• pp.15-22
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• 2008

기존의 MOSFET는 단채널 현상의 증가로 인하여 스케일링에 한계를 가지고 있다. Double-Gate MOSFET (DG-MOSFET)는 소자의 길이가 축소되면서 나타나는 단채널 현상을 효과적으로 제어하는 차세대 소자이다. DG-MOSFET으로 소자를 축소시키면 채널 길이가 10nm 이하에서 게이트 방향뿐만 아니라 소스와 드레인 방향에서도 양자 효과가 발생한다. 또한 게이트 길이가 매우 짧아지면 ballistic transport 현상이 발생한다. 따라서 본 연구에서는 2차원 양자 효과와 ballistic transport를 고려하여 DG-MOSFET의 특성을 분석하였다. 또한 단채널 효과를 줄이기 위해서 $t_{si}$와 underlap 그리고 lateral doping gradient를 이용하여 소자 구조를 최적화하였다.

• 대한기계학회논문집A
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• 제21권12호
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• pp.2106-2113
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• 1997

This paper presents the characteristics of lateral vibrations of rotor system supported by hydrodynamic journal bearings. Finite element model is developed for the dynamic analysis of rotor system. Hydrodynamic bearings are modeled with the distributed springs and dampers in shape of the 2nd order polynomials in the direction of bearing width. Experiments are conducted to measure the natural frequency, and experimental results are compared with the theoretical results that are calculated using the point model and distributed model. Theoretical results using the distributed model agrees better with the measured results as bearing width increases. Also, this method is applied to actual three-stage turbo blower model. Then, critical speed and forced vibration analysis are performed.

• International Journal of Automotive Technology
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• 제3권2호
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• pp.71-78
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• 2002

A new control method far vision-based autonomous vehicle is proposed to determine navigation direction by analyzing lane information from a camera and to navigate a vehicle. In this paper, characteristic featured data points are extracted from lane images using a lane recognition algorithm. Then the vehicle is controlled using new Levenberg-Marquardt neural network algorithm. To verify the usefulness of the algorithm, another algorithm, which utilizes the geometric relation of a camera and vehicle, is introduced. The second one involves transformation from an image coordinate to a vehicle coordinate, then steering is determined from Ackermann angle. The steering scheme using Ackermann angle is heavily depends on the correct geometric data of a vehicle and a camera. Meanwhile, the proposed neural network algorithm does not need geometric relations and it depends on the driving style of human driver. The proposed method is superior than other referenced neural network algorithms such as conjugate gradient method or gradient decent one in autonomous lateral control .

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2479-2490
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• 2020

We performed experiments to measure a single-phase upward flow in a 5 × 5 rod bundle with spacer grids using a particle image velocimetry, focusing on the crossflow. The Reynolds number based on the hydraulic diameter and the bulk velocity is 10,000. The ratio of pitch between rods and rod diameter is 1.4 and spacer grid is installed periodically. The turbulence in the rod bundle results from the combination of a forced mixing and natural mixing. The forced mixing by the spacer grid persists up to 10D_h from the spacer grid, while the natural mixing is attributed to the crossflow between adjacent subchannels. The combined effects contribute to a sinusoidal distribution of the time-averaged stream-wise velocity along the lateral direction, which is relatively weak right behind the spacer grid as well as in the gap. The streamwise and lateral turbulence intensities are stronger right behind the spacer grid and in the gap. Based on these findings, we newly defined a modified mixing coefficient as the ratio of the lateral turbulence intensity to the time-averaged streamwise velocity, which shows a spatial variation. Finally, we compared the developed model with the measured data, which shows a good agreement with each other.