• Geomechanics and Engineering
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• 제29권6호
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• pp.697-706
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• 2022

In order to explore the stable anchoring conditions of coal side under the mining disturbance of soft section coal pillar in Wangcun Coal Mine of Chenghe Mining Area, the distribution model of the anchoring support pressure at the coal pillar side was established, using the strain-softening characteristics of the coal to study the distribution law of anchoring coal side support pressure. The analytical solution for the reinforcement anchorage stress in the coal pillar side was derived with the inelastic state mechanical model. The results show that the deformation angle of the roadway side and roof increases with the roof subsidence due to the mining influence at the adjacent working face, the plastic deformation zone extends to the depth of the coal side, and the increase of anchorage stress can effectively control the roof subsidence and further deterioration of plastic zone. The roadway height and the peak support pressure have a certain influence on the anchorage stress, the required anchorage stress of the coal side rises with the roadway height and the peak support pressure. The required anchorage stress of the coal pillar side decreases as the cohesion between the coal seam and the roof and floor and the anchor length increases. Then, applied the research result to Wangcun coal mine in Chenghe mining area, the design of anchor cable reinforcement support was proposed for the section of coal pillars side that has been anchored and deformed, which achieved great results and effectively controlled the convergence and deformation of the side, providing a safety guarantee for the roadway excavation and mining.

• 한국해안·해양공학회논문집
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• 제27권4호
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• pp.274-279
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• 2015

동해 중부에 위치한 속초항 연안에서 약 11년간 취득한 파랑자료를 스펙트럼법과 파별분석법을 사용하여 분석하고 대표적인 파랑 특성을 검토하였다. 유의파고는 동계에 크고 하계에 작으며, 첨두주기도 동계에 길고 하계에 짧은 특성을 나타내었다. 관측된 최대 유의파고는 8.95 m 였으며 동해선풍에 의하여 발생되었다. 유의파고와 첨두주기 모두 그 분포 형태를 Generalized Gamma 및 Generalized Extreme Value 분포함수보다는 Kernel 분포함수가 보다 잘 재현하였다. 한편, 인근 해역에서의 설계 및 시공에 도움을 줄 수 있도록 파고 자료를 월별 및 파고 구간별로 세분하고 누적출현율을 제시하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권2호
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• pp.150-158
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• 2011

Present study aims to investigate the influence of relative breakwater width W/L (W=width of breakwater, L=wavelength), wave steepness $H_i/gT^2$ (Hi=incident wave height, T=wave period) and relative wave height d/W (d=water depth) on forces in the moorings of horizontal interlaced multi-layered moored floating pipe breakwater (HIMMFPB) model. Studies were conducted on scaled down physical models having three layers of Poly Vinyl Chloride (PVC) pipes, wave steepness $H_i/gT^2$ varying from 0.063 to 0.849, relative width W/L varying from 0.4 to 2.65 and relative spacing S/D=2 (S=horizontal centre-to-centre spacing of pipes, D=diameter of pipes). Peak mooring forces were also measured and data collected is analyzed by plotting non-dimensional graphs depicting variation of $f_s/{\gamma}W^2$ ($f_s$=Sea side Mooring force, ${\gamma}$=specific weight of water) & $f_l/{\gamma}W^2$ ($f_l$=Lee side Mooring force) with $H_i/gT^2$ for d/W varying from 0.082 to 0.276 and also variation of $f_s/{\gamma}W^2$ and $f_l/{\gamma}W^2$ with W/L for $H_i$/d varying from 0.06 to 0.400.

• 화약ㆍ발파
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• 제35권3호
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• pp.1-8
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• 2017

본 연구에서는 다층 주방식 채광 광산에서 우발적 폭발이 일어났을 때 구조변수가 파괴(낙석 등)에 미치는 영향 및 기여도를 평가 분석하였다. 다층 주방식 광산에서 대형 폭발에 따른 최대진동속도 영향을 산출하기 위해 AUTODYN으로 수치해석을 수행하였으며, 각 인자들의 기여도 분석을 위해 강건설계 실험계획법을 이용하여 설계인자를 분석하였다. 분석에 사용된 직교배열은 $L_9(3^4)$ 이었고 변수는 각각 3수준의 값을 갖는 광주의 높이, 광주의 폭, 갱도 폭, 바닥필라 두께 등으로 하였다. 분석결과 폭발원 갱도로 부터 하부레벨 갱도 천반에서 최대진동속도 발생에 가장 큰 영향을 미치는 것은 광주의 높이이며, 이어서 바닥필라, 갱도 폭, 광주의 폭 순으로 나타났다. 수평인접 갱도 측면중앙의 경우는 광주의 폭, 갱도 폭, 광주의 높이, 바닥필라의 두께 순으로 기여율이 평가되었다.

• 한국해안·해양공학회논문집
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• 제27권2호
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• pp.142-147
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• 2015

동해 중북부에 위치한 대진항 북측 연안에서 7년간 취득한 파랑자료를 스펙트럼법과 파별분석법을 사용하여 분석하고 대표적인 파랑 특성을 검토하였다. 유의파고는 동계에 크고 하계에 작으며, 첨두주기도 동계에 길고 하계에 짧은 특성을 나타내었다. 관측된 최대 유의파고는 6.59 m였으며 1216호 태풍 산바(SANBA)에 의하여 발생되었다. 유의파고와 첨두주기 모두 그 분포 형태를 Generalized Gamma 및 Generalized Extreme Value 분포함수보다는 Kernel 분포함수가 보다 잘 재현하였다. 한편, 인근 해역에서의 설계 및 시공에 도움을 줄 수 있도록 파고 자료를 월별 및 파고구간별로 세분하고 누적출현율을 제시하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.875-882
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• 2019

The effects of Triangle Groove Strips (TGS) on Vortex-induced Vibration (VIV) suppression of marine riser are numerically investigated using Computational Fluid Dynamics (CFD) method. The range of Reynolds number in simulations is 4.0 × 10⁴ < Re < 1.2 × 10⁵. The two-dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) equations and Shear Stress Transport (SST) k-ω turbulence model are used to calculate the flow around marine riser. The Newmark-β method is employed for evaluating the structure dynamics of marine riser. The effect of the height ratio (ε) of TGS on VIV suppression is evaluated. The amplitude responses, frequency responses, vortex patterns and the flow around the structures are discussed in detail. With the increase of the height ratio of TGS, the suppression effect of TGS on VIV suppression is improved firstly and then weakened. When ε=0.04, the suppression effect of TGS is the best. Compared with the VIV responses of smooth marine riser, the amplitude ratio is reduced by 38.9%, the peak of the lift coefficient is reduced by 69% and the peak of the drag coefficient is reduced by 40% when Re=6.0 × 10⁴. With the increase of Reynolds number, the suppression effect of TGS on VIV suppression is improved firstly and then weakened. When the Reynolds number is 7.0 × 10⁴, the amplitude ratio can be reduced by 40.1%. As to the large-amplitude vibration cases, the TGS show nice suppression effect on VIV.

• 대한영양사협회학술지
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• 제7권2호
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• pp.153-158
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• 2001

This study examined the age-related patterns in body composition cross-sectionally using Segmental bioelectrical impedance analysis(SBIA), specifically its two components, lean body mass(LBM) and body fat mass, in 1,452 men and 1,436 women with an age range of 19 to over 70 years . Mean height of male subjects was 174.1cm at peak in early 20's and was decreased continuously 0.2-0.3 cm every year. Mean weight was greatest between late 20's and 40's, and was decreased quickly in 70's. Body fat mass was increased steadily before 30's and remained thereafter. Because decreasing lean body mass (LBM), percentage of body fat(PBF) increased continuously with aging. Mean height of female subjects was 161.7 cm at peak in 20's and was decreased steadily around 0.2 cm every year and thus an individual's height was decreased approximately 10 cm in their life cycle. Body weight was increased steadily until 50's and then was decreased. Body fat mass was increased continuously and LBM remained constant and thus PBF was increased steadily with aging. SBIA can be used to compare body composition between genders and between ages. In future studies, SBIA could be applied widely to evaluate variations of body composition in subjects with different nutritional problems.

• 한국습지학회지
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• 제20권1호
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• pp.14-19
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• 2018

본 연구에서는 기존 도시유역 유출해석을 위해 많이 사용되는 SWMM 모형에 초고층 건물의 영향을 고려하는 방법을 제시하였다. 본 연구에서 제시한 방법은 건물의 규모 및 높이를 고려하여 빗물이 지표면에 도달하는 시간을 추가로 계산하고, 이를 반영하여 유역폭을 수정하는 방법이다. 본 연구에서 제안한 방법은 Isidoro et al. (2012)의 실험결과를 이용하여 검증하였다. 결과적으로 SWMM 모형으로 모의한 유출수문곡선은 실험자료와 전체적으로 잘 일치하여, 본 연구에서 제안한 방법이 유효함을 확인할 수 있었다. 두 수문곡선에서 모두 모두 건물의 밀도 증가에 따른 첨두유량의 감소, 첨두시간의 지체 등 유출 반응의 변화가 동일한 것을 확인하였다.

• 대한원격탐사학회지
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• 제28권3호
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• pp.307-318
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• 2012

To understand forest structures, the Geoscience Laser Altimeter System (GLAS) instrument have been employed to measure and monitor forest canopy with feasibility of acquiring three dimensional canopy structure information. This study tried to examine the potential of GLAS dataset in measuring forest canopy structures, particularly maximum canopy height estimation. To estimate maximum canopy height using feasible GLAS dataset, we simply used difference between signal start and ground peak derived from Gaussian decomposition method. After estimation procedure, maximum canopy height was derived from airborne Light Detection and Ranging (LiDAR) data and it was applied to evaluate the accuracy of that of GLAS estimation. In addition, several influences, such as topographical and biophysical factors, were analyzed and discussed to explain error sources of direct maximum canopy height estimation using GLAS data. In the result of estimation using direct method, a root mean square error (RMSE) was estimated at 8.15 m. The estimation tended to be overestimated when comparing to derivations of airborne LiDAR. According to the result of error occurrences analysis, we need to consider these error sources, particularly terrain slope within GLAS footprint, and to apply statistical regression approach based on various parameters from a Gaussian decomposition for accurate and reliable maximum canopy height estimation.

• 대한치과교정학회지
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• 제4권1호
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• pp.31-40
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• 1974

The age of maximum growth increments-the adolescent spurt-is not only of developmental interest but is used as a marker for timing other growth events. And the mandibular growth rate follows the general growth curve, it is essential for an orthodontist to take the current and exact information about physical growth of patients. The author measured and studied the body height and weight of 11,694 children living in Seoul, and calculated out the mean, standard deviation, coefficient value, annual increments, percentage increments of each value, and made diagram to compare it with others. 1. The growth curve shows linear increment tendency until 17 years of age in male, 15 years in female. 2. The annual increment curves of body height and weight reveals the most peak value in 14-16 years in male and 11-14 years in female. 3. During 11-14 years of age, female growth exceed the male growth in the body height growth. And in weight growth, female growth exceed the male growth during 6-7 years and 11-12 years to show twice crossing. 4. It seemed that until 11-12 years in male and until 9-10 years in female the height growth show the priority to weight growth. And from 17 years in male and 15 years in female the body growth reveals the balanced growth pattern. 5. The time of changes of standard deviation curves of body height and weight coincided with that of annual increments. 6. The prominent high value of body height and weight in the comparison with other data may be due to the secioeconomical and nutritional, environmental influence. 7. The growth accerlation phenomena was detectable.