• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.344-347
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• 2008

Ocean surface waves may be modified by ocean current and their observation may be severely distorted if the observer is on a moving platform with changing speed. Tidal current near a sill varies inversely with the water depth, and results spatially inhomogeneous modulation on the surface waves near the sill. For waves propagating upstream, they will encounter stronger current before reaching the sill, and therefore, they will shorten their wavelength with frequency unchanged, increase its amplitude, and it may break if the wave height is larger than 1/7 of the wavelength. These small scale (${\sim}$ 1 km changes is not suitable for satellite radar observation. Spatial distribution of wave-height spectra S(x, y) can not be acquired from wave gauges that are designed for collecting 2-D wave spectra at fixed locations, nor from satellite radar image which is more suitable for observing long swells. Optical images collected from cameras on-board a ship, over high-ground, or onboard an unmanned auto-piloting vehicle (UAV) may have pixel size that is small enough to resolve decimeter-scale short gravity waves. If diffuse sky light is the only source of lighting and it is uniform in camera-viewing directions, then the image intensity is proportional to the surface reflectance R(x, y) of diffuse light, and R is directly related to the surface slope. The slope spectrum and wave-height spectra S(x, y) may then be derived from R(x, y). The results are compared with the in situ measurement of wave spectra over Keelung Sill from a research vessel. The application of this method is for analysis and interpretation of satellite images on studies of current and wave interaction that often require fine scale information of wave-height spectra S(x, y) that changes dynamically with time and space.

• 국제물리치료학회지
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• 제2권2호
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• pp.324-328
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• 2011

The purpose of this study is to measure the effect of change in heel height on lower extremities activity of young women on high-heeled shoes that young women prefer from more kinetic and realistic perspective as this study changes the degree of slope on a treadmill. The study subjects are 15 young and healthy women who do not have any external injuries or problem with walking and understand the purpose of this study clearly. They wore three different height of heels(1cm, 7cm, 12cm) and walked on a treadmill at a constant speed of 3km/h. EMG value of four muscles (anterior tibial muscle, gastrocnemius muscle, straight muscle of thigh, and biceps muscle of thigh) were collected when walking and the change according to the height of heels were analyzed using one-way ANOVA. Multiple comparison analysis on anterior tibial muscle and heel height showed that the group with 12cm heel showed significantly high muscle activation compared to the groups with 1cm and 7cm heels. The result of this study can be used for various perspectives from inferring and mediating problems caused by wearing high heels on different ground slopes for a long time.

• 한국운동역학회지
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• 제25권4호
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• pp.383-391
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• 2015

Objective : The purpose of this study was to investigate the effects of dynamic squats with slope-whole body vibration (WBV) on the trunk and lower limb in muscle activities. Method : 9 healthy women (age: $21.1{\pm}0.6years$, height: $160.5{\pm}1.4cm$, body weight: $50.5{\pm}2.4kg$) were recruited for this study. Muscle activities in the trunk and lower limb muscles, including biceps femoris (BF), rectus femoris (RF), rectus abdominum (RA), gastrocnemius (GCM), iliocostalis lumborum (IL) and tibialis anterior (TA), were recorded using an EMG measurement system. The test was performed by conducting dynamic squats with slope-WBV using frequency (10Hz, 50Hz), amplitude (0.5mm), and degree ($0^{\circ}$, $5^{\circ}$). Experimental method consisted of 2-pre-sessions and 1-test-session for 20 seconds. Results : The results showed that the muscle activities of the trunk and low limb muscles increased significantly with the $5^{\circ}$ slope and lower frequency (10Hz) except for in the TA. From this result, we confirmed that the slope and WBV could efficiently affect stimulation, enhancing muscle activities by facilitating neural control trail and muscle chain tightness. Conclusion : Utilizing the slope-WBV device while squatting could give positive effects on muscle activation in the trunk and lower limb muscles and provide neural stimulation, enhancing muscle chain of control subsystem through TVR (tonic vibration reflex).

• 한국해안·해양공학회논문집
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• 제30권5호
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• pp.207-216
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• 2018

본 연구에서는 한계평형해석에 근거하는 Talren97과 SoilWorks 그리고 유한요소해석에 근거하는 Midas GTS를 이용하여 비탈면의 최소안전율을 비교 분석하였다. 해석 변수로는 비탈면 높이, 소단조건, 지반정수, 지하수위, 비탈면 경사이며 지하수위를 제외한 모든 변수들에 대한 해석은 건기와 우기로 나누어 수행하였다. 그 결과 동일한 이론을 기반으로 하는 Talren97과 SoilWorks에 의한 비탈면 최소안전율은 동일한 값을 나타내어 프로그램간의 차이는 없는 것으로 확인되었다. 한계평형해석에 비하여 유한요소해석 결과가 다소 높은 안전율을 나타내었으며 평균적으로 약 2.4% 높게 나타나는 것으로 확인되었다. 그러나 한계평형해석과 유한요소해석의 결과 값 차이는 실무에서는 무시할 수 있는 범위이므로 프로그램 및 해석방법에 따른 비탈면 안전율의 차이는 없는 것으로 판단되었다.

• 한국지반공학회논문집
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• 제21권5호
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• pp.7-31
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• 2005

강우로 인한 철도사면의 활동은 사면의 안정성에 영향을 끼치며 결국은 철도의 운행에 큰 영향을 미친다. 비록 소량의 토체의 활동이 발생하여 선로상으로 이동되더라도 탈선을 일으킬 가능성이 있으므로 철도운영에 있어 사면의 안정은 중요한 분야중의 하나이다. 따라서, 본 연구에서는 철도연변 사면에서 관측된 강우로 인한 사면의 거동특성을 분석하였다. 전체 23개소에 대한 조사가 이루어 졌으며, 관측결과 강우로 인한 사면의 붕괴 패턴은 크게 4가지로 구분될 수 있었다. 이러한 분류는 붕괴된 사면의 형태를 기준으로 이루어 졌다. 본 연구결과에 따르면 사면의 제원(사면의 높이와 길이)은 관측된 활동 패턴과 직접적인 상관성을 보이지는 않았지만, 사면의 형태 및 지질학적 특성은 각기 다른 활동타입의 발생에 영향을 미치는 것으로 나타났다.

• Geomechanics and Engineering
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• 제36권5호
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• pp.489-509
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• 2024

Slope stability analysis and prediction are of critical importance to geotechnical engineers, given the severe consequences associated with slope failure. This research endeavors to forecast the factor of safety (FOS) for slopes through the implementation of six distinct ML techniques, including back propagation neural networks (BPNN), feed-forward neural networks (FFNN), Takagi-Sugeno fuzzy system (TSF), gene expression programming (GEP), and least-square support vector machine (Ls-SVM). 344 slope cases were analyzed, incorporating a variety of geometric and shear strength parameters measured through the PLAXIS software alongside several loss functions to assess the models' performance. The findings demonstrated that all models produced satisfactory results, with BPNN and GEP models proving to be the most precise, achieving an R² of 0.86 each and MAE and MAPE rates of 0.00012 and 0.00002 and 0.005 and 0.004, respectively. A Pearson correlation and residuals statistical analysis were carried out to examine the importance of each factor in the prediction, revealing that all considered geomechanical features are significantly relevant to slope stability. However, the parameters of friction angle and slope height were found to be the most and least significant, respectively. In addition, to aid in the FOS computation for engineering challenges, a graphical user interface (GUI) for the ML-based techniques was created.

• 한국운동역학회지
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• 제34권3호
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• pp.105-114
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• 2024

Objective: The purpose of this study is to provide quantitative data through biomechanics analysis of lower extremity movements according to uphill slope when pedaling a cycle. The method of the study were as follow. Method: Ten healthy adult males (age: 30.18 ± 4.2 yrs., height: 173.75 ± 2.99 cm, weight: 66.9 ± 2.64 kg), and who have a weekly exercise distance of more than 100 km and participated in amateur competitions with no lower extremity musculoskeletal injury within the past six months participated in this study. The experiment was conducted at three uphill slopes of 8%, 14%, and 20%, and the intensity of the experiment was 5.5 to 6 watts per kg of body weight for each slope for 4 minutes. A 3-Dimensional motion analysis with eight infrared cameras (sampling rate: 200 Hz) and five-channel of EMG (sampling rate: 2,000 Hz) was performed. In this study event 1, 2, 3, and 4 were set at angular position of pedal at 330°, 30°, 150° and 210°, respectively. Also connections of events were set as phases (P1~P4). A one-way ANOVA with repeated measures was conducted to verify the intervention effect and the statistical significance was set at α=.05. Results: As the uphill slope increased, the position of COM moved further back from the center of the cycle. In the knee joint, P1 and P3 showed greater ROM and higher angular velocity as the slope increased, while P2 and P4 showed opposite results. As the slope increased the peak activation timing was found to be faster for the vastus lateralis and biceps femoris, while the peak activation timing for the medial gastrocnemius muscle was delayed. Conclusion: There was a difference in kinematics as the uphill slope increased during cycling, and the difference between 8% and 14% showed a greater change than the difference between 14% and 20%.

• 한국문헌정보학회지
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• 제11권
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• pp.3-42
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• 1984

This is to establish a model of the standardization of shelving, chairs, tables and card cabinets for college and university libraries in Korea. The size of furniture was measured on the base of the analysis of the human factors, such as the standard size of human bodies of the college students in Korea, the scope of work area, the moving degree of muscles, the limit of the visual field, etc. The results of this study are as follows: 1. It is desirable that the standard shelf length should be 800mm. and the maximum . shelving height should not exceed 1,803mm. And it is desirable that the bottom shelf has a ground clearance of about $210\~390mm$. 2. It is advisable that the sloped shelving has the slope from about 1,000mm, or 930mm, and the gradient should be $19^{\circ}$ from the above mentioned sloping position and the bottom of each shelf. And it is desirable that the slope height of each shelf should be 77mm. 3. It is advisable that the seat area for users should be $410\~420\times420mm$, and the seat height should be $390\~0400mm$. 4. It is desirable that the table size per user should exceed $490\times880\~890mm$, and the table height should be $680\~690mm$. 5. It is advisable that each tray of the card cabinet should hold about 740 cards, and the depth should exceed 430mm. And it is desirable that the maximum height of card cabinets should be as follows: 60du(drawer units)-$1,400\~1,460mm$, 30du-1, 300mm, 15du-1,100mm. In addition, it is advisable that the 30du cabinet should accomodate 5 trays vertically and 6 trays horizontally for avoiding the worst working position rather than 6 trays vertically and 5 trays horizontally. 6. It is desirable that the height of sliding reference shelves in card cabinets, or consultation tables should be 900mm. But in the case of the sliding shelves, it is desirable to be as follows: 15du-900mm when the card cabinet height is more than 1,100, mm, but unnecessary when less than 1,100mm high, 30du-1,000mm, or 1,100mm in the case of $5\times6du$, but 900mm in the case of $6\times5du$, $60du-900\~950mm$ when the card cabinet height is $1,400\~1,460mm$.

• 터널과지하공간
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• 제16권6호
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• pp.506-525
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• 2006

복잡한 지층 및 지질구조 특성을 보이는 대규모 절취사면의 경우 설계 시의 조사 및 시험의 한계성 등으로 인하여 지반특성파악 및 설계정수의 산정이 어려워 시공 중 사면활동이 빈번하게 발생하고 있다. 이러한 경우 시공 중 절취상태에서 지반특성에 부합된 최적의 조사 및 분석 과정을 통하여 합리적인 대책방안을 강구해야 한다. 본 연구에서는 변성퇴적암류로 구성된 현존 국내 최대 규모의 대절토사면 (연장520 m, 최대절취고 약 122 m, 최대법면길이 약 212 m)을 대상으로, 활동이력분석과 시공 중 지반조사를 통하여 사면의 붕괴원인분석에 관한 시공사례연구를 실시하였다. 원설계 시 대상사면의 경사는 발파암 기준 1:0.7을 적용하여 일부 시공하였으나 절취과정에서 지질요인, 강우 등 안정성을 저해하는 제반 요인에 의하여 다수의 지반활동이 발생하였으며, 계속적인 지반활동으로 인하여 대규모 산사태가 예상되는 매우 위험한 지반상태를 나타내고 있어. 이에 총 3차의 설계변경을 통해 사면의 장기 안정성을 확보하였다. 이러한 사례연구를 통하여, 본 지반조건과 유사한 지질 및 불연속면 특성을 나타내는 암반사면에 대한 안정성 분석, 평가 및 대책방안 수립을 위한 참고 자료가 되기를 기대한다.

• Geomechanics and Engineering
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• 제5권2호
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• pp.143-164
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• 2013

Calculation of seismic displacements in reinforced slopes plays a crucial role in appropriate design of these structures however current analytical methods result indifferent values for permanent displacements of the slope. In this paper, based on limit equilibrium and using the horizontal slices method, a new formulation has been proposed for estimating the seismic displacements of a reinforced slope under earthquake records. In this method, failure wedge is divided into a number of horizontal slices. Assuming linear variations for tensile forces of reinforcements along the height of the slope, the coefficient of yield acceleration has been estimated. The simplicity of calculations and taking into account the frequency content of input triggers are among the advantages of the present formulation. Comparison of the results shows that the yield acceleration calculated by the suggested method is very close to the values resulted from other techniques. On the other hand, while there is a significant difference between permanent displacements, the values obtained from the suggested method place somehow between those calculated by the other techniques.