• 한국해양공학회지
• /
• 제10권3호
• /
• pp.34-43
• /
• 1996

In this study basic equations of fiber orientations is cimpared with experimental results. It is found that fiber orientations of short fiber reinforced polymeric composite under compression molding are governed by slope of flow speed in x-y direction. Fiber orientation angle of mold is also found to increase with closure speed and the compression ratio. At the middle of the mold, the slope of flow speed is larger in x-direction than in y-direction. At the wall of the mold, the shope of flow speed in y-direction occurs due to the effect of friction, hence affects the fiber orientation. The effect of partial flow, which incurs y-direction orientation causes to increase the fiber orientation angle at the fore part of the flow.

• Journal of Welding and Joining
• /
• 제15권6호
• /
• pp.85-95
• /
• 1997

This study is to investigate the optimum conditions of Nd:YAG laser beam welding for Zircaloy-4 end cap closure by optical fiber transmission. Laser welding parameters which affect the penetration depth and bead width were experimentally examined using the various beam radius by the beam quality analyzer, joint geometries of end cap and the laser parameters which mean pulse width, repetition rate and pulse energy. Also, an optimum welding speed and the effect of assistant gas with varying the flow rate of He were investigated. We found that the laser average power for the end cap welding will be 230W and rotation speed must not exceed 8 RPM, the best position of focus using optical fiber with 600.mu.m will be 2 to 3mm below the surface of the material.

• 설비공학논문집
• /
• 제12권7호
• /
• pp.697-702
• /
• 2000

This study is to investigate the pressure wave characteristics and the maximum pressure rise generated by instantaneous valve closure at the end of the straightening copper piping system. Experiments were conducted under the following conditions : initial pressure 1~5 bar, flow velocity 0.6~3.0 m/s and water temperature $20^{\circ}C$ . Results indicated that the peak pressure generated by quick valve closure reached Joukowsky's value. And we also found that the maximum pressure rise and the pressure history were depended on not only closing time but also flow velocity.

• 한국도로학회논문집
• /
• 제18권3호
• /
• pp.11-19
• /
• 2016

PURPOSES : This study supports the evidence that it is possible to rehabilitate a damaged pavement with a lane closure specifically based on the Gimcheon~Sunsan project. METHODS : The prediction results from the simulation programs were compared with field monitoring, which focused on traffic management planning, congestion (length, time, and passing speed), bypass, and user cost, among others. RESULTS : The research results showed that lane closure application and pavement repair of the aged pavement in Korea were possible, even though the prediction results were minimally different from the field monitoring. The road agency contributes to service life extension of the rehabilitated pavement using this method. CONCLUSIONS : A marginal effect caused by the lane closure was observed on travelling users or vehicles, and the user cost of pavement repair decreased. Therefore, introducing the repair method or rehabilitation in Korea is possible. Information dissemination through various media was properly done to execute the project well. Moreover, the construction area traffic utilized nearby alternative roads. Therefore, improving the repaired pavemen's service life while ensuring that the pavement management agency can provide a road with comfortable user riding quality was possible.

• 설비공학논문집
• /
• 제18권1호
• /
• pp.17-23
• /
• 2006

This study is to investigate the pressure wave characteristics and the maximum pressure rise generated by instantaneous valve closure at the end of the straightening polybutylene piping system. Experiments were conducted under the following conditions: initial pressure $1\~5$ bar, flow velocity $\~0.5-3.0m/s$ and water temperature $25^{\circ}C$. Results indicated that the peak pressure generated by quick valve closure reached Joukowsky's value. We also found that the maximum pressure rise and the pressure history depended on not only initial steady pressure but also flow velocity.

• Journal of Mechanical Science and Technology
• /
• 제14권5호
• /
• pp.562-568
• /
• 2000

The pressure in a water-entry induced cavity, is analyzed up to the closed cavity (bubble). Water-entry is a highly transient phenomenon, and the evolution of the water-entry cavity must be explained by considering the entry speed, shape of the solid body, atmosphere pressure, and cavity pressure as the primary variables. This work is an extension of the cavity dynamics model recently reported by Lee (l997a). To extend the model for a wide range of entry speeds the cavity pressure is calculated from a one-dimensional quasi-steady flow model. The estimation of the cavity pressure allows us to explain the experimentally observed surface closure phenomena at low entry speeds. Predictions for the time of surface closure are compared with the published experimental data.

• 한국환경복원기술학회지
• /
• 제12권3호
• /
• pp.98-105
• /
• 2009

The objective of this study is to develop numerical simulation model for analysing the wind speed reduction effect by coastal forest belts. The horizontally homogeneous turbulent flow equations, which are derived from the Reynolds-averaged Navier-Stokes method, both above the tree canopy and within the canopy were first formulated, and a first-order closure scheme with the capability of accounting the bulk momentum transport term within the canopy was employed. The averaged equations were solved numerically by finite difference method, FTCS (forward time centered space) scheme. The proposed model was also used to numerically investigate the effects of structural characteristic of forest belt on the wind speed. The effects of maximum leaf area density were evaluated, with the leaf area density of $1.0m^2/m^3$, $2.0m^2/m^3$, $3.0m^2/m^3$, and $4.0m^2/m^3$. Vertical distributions of leaf area, both uniform and varied distribution with a height, were also considered. A comparison of wind profile indicated that there was in good agreements between simulated and measured wind speed. Also, the results showed horizontal wind speed decreased under a height of the tree with increasing maximum leaf area density. In conclusion, in applications where computational efficiency and simplicity are desirable, the proposed numerical model has of great capability to determine the vertical turbulent momentum transport and wind profile in the costal forest belt.

• Journal of Trauma and Injury
• /
• 제36권4호
• /
• pp.447-450
• /
• 2023

Traumatic abdominal wall hernia is a rare presentation, most commonly reported in the context of motor vehicle accidents and associated with blunt abdominal injuries and handlebar injuries in the pediatric population. A 13-year-old boy presented with multiple traumatic injuries and hemodynamic instability after a high-speed motor vehicle accident. His injuries consisted of massive traumatic abdominal wall hernia (grade 4) with bowel injury and perforation, blunt aortic injury, a Chance fracture, hemopneumothorax, and a humeral shaft fracture. Initial surgical management included partial resection of the terminal ileum, sigmoid colon, and descending colon. Laparostomy was managed with negative pressure wound therapy. The patient underwent skin-only primary closure of the abdominal wall and required multiple returns to theatre for debridement, dressing changes, and repair of other injuries. Various surgical management options for abdominal wall closure were considered. In total, he underwent 36 procedures. The multiple injuries had competing management aims, which required close collaboration between specialist clinicians to form an individualized management plan. The severity and complexity of this injury was of a scale not previously experienced by many clinicians and benefited from intrahospital and interhospital specialist collaboration. The ideal aim of primary surgical repair was not possible in this case of a giant abdominal wall defect.

• 비파괴검사학회지
• /
• 제18권2호
• /
• pp.85-91
• /
• 1998

핵연료 제작과정에서 봉단마개 용접부는 완벽한 품질이 요구되고 있다. 본 연구에서는 와전류탐상방법을 이용하여 봉단마개 용접부의 검사를 위한 기초적인 방법을 연구하였다. 봉단마개 용접부 와전류검사를 위한 주사속도와 와전류신호의 최대주파수를 찾았고 잡음신호제거를 위해 대역통과여파기(0-250Hz)론 사용하였다. 이러한 와전류탐상방법은 직경 0.35mm의 작은 핀홀결함에서도 좋은 감도를 얻을 수 있었다.

• 한국임상보건과학회지
• /
• 제2권4호
• /
• pp.209-215
• /
• 2014

Purpose. The purpose of this study was to determine the relationship between typing speed required dexterity of hand and visual perception. Method. We studied 50 people who were not experience of hand injury in K university. Typing speed, hand dexterity and visual perception were measured using purdue pegboard test, MVPT-3 and 'Cheongsando' in Hancom typing program. Results analysis was used Pearson correlation coefficient of the SPSS 10.0. Result. In this study, the typing speed showed a positive correlation with the figure ground, but there was no correlation visual closure and visual discrimination. Conclusion. Typing speed was correlated with hand dexterity and figure ground. Therefore, utilizing a computer keyboard at treatment can be expected to enhance hand function and visual perception.