• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.83-87
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• 1995

Impact-bouncing height of steel balls dropped from 1m height on various floor materials were measured to evaluate impact-bouncing characteristics depending on floor materials and the effect of these properties on walkability and fatigue of humanbody. Stone and tile finished concrete floor showed the highest bouncing height of around 70%, and soil showed the lowest bouncing height of around 3%. The second highest bouncing height was about 40% which corresponded to terazo finished concrete floor and about twice as high as the bouncing height on concrete floor without finishing. The impact-bouncing height could be lowered to 15~20% by using gum tile on concrete floor. Steel showed similar bouncing height to concrete floor, and wood-based materials showed the second lowest bouncing height next to soil. Among wood-based materials, hardwood species having higher specific gravities showed relatively high bouncing height of 8~24%, softwood species having low specific gravities showed relatively lower bouncing height of 5~18%, and wood composites showed bouncing height of 8~18%. Among all the materials used in this study, wood-based floor materials corresponded to the bouncing height of 10~15% which is considered to be best for humanbody. Surface painting on wood-based materials increased the bouncing height, and the number of bouncing of steel balls after dropping from 1m height increased as the bouncing height increased.

• 한국전문물리치료학회지
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• 제31권1호
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• pp.29-39
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• 2024

Background: Landing from a step or stairs is a basic motor skill but high incidence of lateral ankle sprain has been reported during landing with inverted foot. Objects: This study aimed to investigate the effect of landing height and visual feedback on the kinematics of landing and supporting lower limbs before and after the touch down and the ground reaction force(GRF)s. Methods: Eighteen healthy females were voluntarily participated in landing from the lower (20 cm) and the higher (40 cm) steps with and without visual feedback. To minimize the time to plan the movement, the landing side was randomly announced as a starting signal. Effects of the step height, the visual feedback, or the interaction on the landing duration, the kinematic variables and the GRFs at each landing event point were analyzed. Results: With eyes blindfolded, the knee flexion and ankle dorsiflexion on landing side significantly decreased before and after the touch down. However, there was no significant effect of landing height on the anticipatory kinematics on the landing side. After the touch down, the landings from the higher step increased the knee flexion and ankle dorsiflexion on both landing and supporting sides. From the higher steps, the vertical GRF, anterior GRF, and lateral GRF increased. No interaction between step height and visual feedback was significant. Conclusion: Step height and visual feedback affected the landing limb kinematics independently. Visual feedback affected on the landing side while step height altered the supporting side prior to the touch down. After the touch down, the step height had greater influence on the lower limb kinematics and the GRFs than the visual feedback. Findings of this study can contribute to understanding of the injury mechanisms and preventing the lateral ankle sprain.

• 한국대기환경학회지
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• 제21권2호
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• pp.179-189
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• 2005

Recently air quality modeling studies for industrial complex and large cities located in the coastal regions have been carried out. Especially, the representation of atmospheric flow fields within a model domain is very important, because an adequate air quality simulation requires an accurate portrayal of the realistic three -dimensional wind fields. Therefore this study investigated effect of using high resolution terrain height data in numerical simulation. So the experiments were designed according to the detail terrain height with 3second resolution or not. Case 30s was the experiment using the terrain height data of USGS and Case 3s was the other using the detail terrain height data of Ministry of Environment. The results of experimental were more remarkable. In Case 3s, temperature indicated similar tendency comparing to observational data predicting maximum temperature during the daytime and wind speed made weakly for difference of terrain height.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.313-316
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• 2008

Although the positioning accuracy of the Global Positioning System (GPS) has been studied extensively and used widely, it is still limited due to errors from sources such as the ionospheric effect, orbital uncertainty, antenna phase center variation, signal multipath and tropospheric influence. This investigation addresses the tropospheric effect on GPS height determination. Data obtained from GPS receivers and co-located surface meteorological instruments in 2003 are adopted in this study. The Ministry of the Interior (MOl), Taiwan, established these GPS receivers as continuous operating reference stations. Two different approaches, parameter estimation and external correction, are utilized to correct the zenith tropospheric delay (ZTD) by applying the surface meteorological measurements (SMM) data. Yet, incorrect pressure measurement leads to very poor accuracy. The GPS height can be affected by a few meters, and the root-mean-square (rms) of the daily solution ranges from a few millimeters to centimeters, no matter what the approach adopted. The effect is least obvious when using SMM data for the parameter estimation approach, but the constant corrections of the GPS height occur more often at higher altitudes. As for the external correction approach, the Saastamoinen model with SMM data makes the repeatability of the GPS height maintained at few centimeters, while the rms of the daily solution displays an improvement of about 2-3 mm.

• Tribology and Lubricants
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• 제34권6호
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• pp.226-234
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• 2018

Copper chemical mechanical planarization (CMP) has become a key process in integrated circuit (IC) technology. The results of copper CMP depend not only on the mechanical abrasion, but also on the slurry chemistry. The slurry used for Cu CMP is known to have greater chemical reactivity than mechanical material removal. The Cu CMP slurry is composed of abrasive particles, an oxidizing agent, a complexing agent, and a corrosion inhibitor. Citric acid can be used as the complexing agent in Cu CMP slurries, and is widely used for post-CMP cleaning. Although many studies have investigated the effect of citric acid on Cu CMP, no studies have yet been conducted on the interfacial friction characteristics and step height reduction in CMP patterns. In this study, the effect of citric acid on the friction characteristics and step height reduction in a copper wafer with varying pattern densities during CMP are investigated. The prepared slurry consists of citric acid ($C_6H_8O_7$), hydrogen peroxide ($H_2O_2$), and colloidal silica. The friction force is found to depend on the concentration of citric acid in the copper CMP slurry. The step heights of the patterns decrease rapidly with decreasing citric acid concentration in the copper CMP slurry. The step height of the copper pattern decreases more slowly in high-density regions than in low-density regions.

• International journal of advanced smart convergence
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• 제8권2호
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• pp.211-217
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• 2019

This study is designed to reduce worker fatigue, improve efficiency and provide a functional working environment based on previous studies that pain occurs in the shoulder area, especially the upper trapezius muscle, when the keyboard height is not appropriate. In this study, the height of the keyboard is four, the height of the elbow and desk is the same height, the height of the desk is 3cm lower than the elbow, the height of the desk is 6cm high, and the height is 9cm high. When working on the keyboard, the wrist and forerunner were organized into four groups of 10 people so that the height was different for each group. When the height of the keyboard is given in various ways compared to the height of the elbow of the subject, it is verified whether there is a difference in the RMS (Root Mean Square) of the upper trapezius muscle. The results of this study showed that the muscle activity of the upper trapezius muscle cap was significant only in the left and right keyboard height -4cm, 0cm, +4cm, +8cm group, but the difference in muscle activity was not significant in the rest group. The first study will require a study of the control of the factors affecting the tension of the subjects, the measurement of muscle activity against various muscles, and whether the length of the shoulder and fingertips of the subject affect muscle activity according to the keyboard type.

• 한국해안·해양공학회논문집
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• 제34권6호
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• pp.211-221
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• 2022

파의 처오름높이는 제방, 호안 및 방파제와 같은 해안 구조물의 설계에 영향을 미치는 가장 중요한 매개변수 중 하나이다. 본 연구에서는 비정수압 수치모형인 SWASH(Zijlema et al., 2011)를 이용해 고정된 수중 및 부유식 사각형 구조물에 의한 고립파의 처오름높이 저감 효과를 분석하였다. SWASH 수치모형이 고립파의 전파, 쇄파 및 처오름현상을 매우 잘 재현하는 것을 확인하였다. 또한 수중 및 부유식 사각형 구조물에 의한 고립파의 파랑변형을 잘 재현하는 것을 확인하였다. 마지막으로 수중 및 부유식 사각형 구조물의 처오름높이 저감 효과를 검토하였다. 부유식 구조물의 에너지 감쇠효과는 수중 구조물보다 크고, 처오름높이 저감에 더 효과적인 것으로 나타났다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.89-92
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• 2007

This investigation aims at calculating the geoid height, distance between the ellipsoidal height and the orthometric height by GPS/Levelling data for nationwide 58 Bench Marks, and calculating the effect of geoid height to engineering public works. The accuracy of the results from baseline analyses and adjustment of a network. using GPS surveying data by nationwide 58 BM show 4mm for horizontal direction and 7cm for vertical direction. The 58 geoid height was calculated by GPS/Levelling. For a construction work field GPS/Levelling for distributed 4 BM in test area can calculate the orthometric height in 20 ppm relativity accuracy with 95% reliability. Besides the calculated geoid height in the investigation was 0.367m higher than EGM96 model. The test results of a engineering work site, the result by EGM96 model was 1.8cm in 10km and it was also 3.6cm in interpolation method. The results show that it is equivalent to levelling of $20mm\sqrt{S}$.

• 생물환경조절학회지
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• 제19권4호
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• pp.240-245
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• 2010

절화장미의 새로운 수경재배 방식으로 용기재배를 제시하기 위하여 배수구의 높이와 적정 배지를 설정하는 두가지 시험을 수행하였다. 용기재배 시 적정한 배수구 높이를 설정하기 위하여 규격이 $30{\times}30{\times}25cm$인 사각용기에 배수구를 0, 3, 6, 9cm 높이로 처리하였을 때 수량은 3cm 배수구 처리가 많았으나 절화품질은 처리간 차이가 발생하지 않았다. 정식후 생존율은 각각 100, 100, 92, 92%였다. 배수구 높이와 배지조성의 관계를 구명하기 위하여 배수구 높아가 0, 3cm인 용기에 배지을 코이어와 펄라이트 단용 및 혼용하여 7가지 배지를 조성하였다. 수분센서를 이용하여 수분함량이 -5kPa에 도달했을 때 급액을 했을 때 코이어 혼합비율이 높은 배지와 3cm 배수구 높이 처리가 급액횟수가 감소하였다. 화중을 제외한 절화의 상품성과 2차 수확까지의 절화 수량은 배수구의 높이에 따른 차이는 인정되지 않았고 3차 수확이후의 수량은 3cm 배수구 처리가 많았다. 배지별로는 코이어의 혼합 비율이 높은 처리에서 수량과 상품성이 우수하였다. 수량은 배수구를 높인 처리구가 절화품질과 수량이 많았으며, 펄라이트의 혼합비율이 높은 배지에서 수량이 감소하는 경향을 나타내었다.

• 한국엔터테인먼트산업학회논문지
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• 제13권1호
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• pp.207-215
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• 2019

본 연구는 뇌졸중 편마비 환자 12명을 대상으로 지팡이 높이에 따라 선 자세 시 양측 발의 압력, 보행 시 보행 속도의 변화를 알아보고자 하였다. 선 자세 시 발의 압력은 풋스캔(Foot scan system, 한국)을 사용하여 측정하였다. 보행 시 보행 속도 차이는 Optogait를 사용하여 측정하였다. 본 연구의 결과는 비 마비 측 발의 압력에서 넙다리뼈 큰 돌기 높이, 넙다리뼈 큰 돌기 위 5cm, 넙다리뼈 큰 돌기 위 10cm 순으로 큰 값을 나타내었으며 유의한 차이가 있었다. 마비 측 발의 압력은 넙다리뼈 큰 돌기 위 10cm, 넙다리뼈 큰 돌기 위 5cm, 넙다리뼈 큰 돌기 순으로 큰 값을 나타내었으며 유의한 차이가 있었다. 이는 지팡이 높이가 높을수록 마비측으로 무게중심이 이동하여 체중지지율이 높아진 것을 알 수 있었다. 보행 속도는 넙다리뼈 큰 돌기 위 5cm, 넙다리뼈 큰 돌기 10cm, 넙다리뼈 큰 돌기 높이에서 미세한 차이는 보였으나 통계학적으로 유의한 차이가 나타나지 않았다. 이는 지팡이 높이가 보행 속도 능력을 변화시킬 만큼 크지 않았다는 것을 볼 수 있었다. 본 논문은 지팡이 높이가 뇌졸중 편마비 환자의 선 자세 시 체중지지율과 보행 시 보행 속도에 대해 알아보고자 하였으며, 차후 임상에서 뇌졸중 편마비 환자들의 지팡이를 적용한 선 자세 또는 보행을 위한 치료에서 지팡이 높이를 설정할 때 기초자료를 제공할 수 있을 것으로 생각된다.