• The Korean Journal of Ecology
• /
• 제21권5_3호
• /
• pp.713-721
• /
• 1998

The effects of artificial interference on the vegetation landscape in Mt. Nam of Seoul, Korea were clarified by analysing the distribution of vegetation landscape element and the number and size of patch depicted as a vegetation map in terms of landscape ecological principles. The effects of artificial interference on vegetation were also confirmed from the environmental gradient analysis on plant community extended from the lowland to the peak of that mountain. Vegetation landscape elements were divided into plantation and secondary forest in actual vegtation map. The ratio of plantation to secondary forest was higher in the lowland below mid-slope and the southern slope. Most afforested land were occupied by Robinia pseudoacacia and Populus tomentoglandulosa, Pinus rigida, P. koraiensis, Metasequoia glyptostroboides, Alnus hirsuta and so on are localy planted. In addition, projects to replace those afforested trees by P. densiflora as a kind of campaign for "Restoration of the one original feature of Mt. Nam" or to replace those tree species by planting young Abies holophylla or P. koraiensis under the mature afforested trees are also carried out in recent years. In cases of secondary forest, the southern slope was dominated by P. densiflora and the northern one by Q. mongolica. But the lowland of the northern slope is dominated by P. densiflora as the same as that in the southern slope. Vegetation landscape elements in Mt. Nam were much simplified comparing with that of suburban area around Seoul. The number of patches, which reflects the degree of diverse artificial interference was more in the lower area than in the upper area and more in the southern slope than in the northern one. On the other hand, the size of patch showed the antagonistic tendency to that of the number of patch. As a result of environmental gradient analysis, vegetation distribution in Mt. Nam was different from that in suburban area around Seoul. For example, Alnus japonica community, Zelkova serrata community, and Carpinus laxiflora community, which is established in mountain comparatively rare in artificial interference disappeared in Mt. Nam. As a result of analysis on vegetational succession in P. densiflora community and Q. mongolica community, both communities showed a tendency of retrogressive succession differently from that in control site located in suburban area around Seoul. In addition, species composition of P. densiflora and Q. mongolica communities in Mt. Nam were also different from those in Mt. Surak located around Seoul. It was interpreted that those results were originated from the environmental pollution and excessive arti ficial interferences.rferences.

• The Korean Journal of Ecology
• /
• 제21권5_3호
• /
• pp.649-663
• /
• 1998

The clarify the ecological properties, and to predict change of understory vegetation of mt. Nam Park, population dynamics and interspecific competition of D. smilacinum and D. viridescens, which grow in understory of deciduous broad-leaved forest and pseudo-annuals, were studied from May 20 to May 30 1998. The depth of litter layer, soil moisture content, soil organic matter and soil texture were surveyed in 18 populations (15 D. smilacinum populations and 3 D. viridescens populations). Mean litter layer of d. smilacimum population was thinner than that of D. viridescens populations). Mean litter layer of D. smilacnum population was thinner than that of D. viridescens population. The contents of soil moisture and organic matter of D. smilacinum population were lower than that of D. viridescens population. The D. smilacinum growed in broad range of soil texture but D. viridescens in loamy soil. Because D. smilacinum could tolerate more broad range of soil moisture and soil texture than D. viridescens, the former covered the herb layer in earlier stage and the latter introduced in later stage when rhizome could grow easily. The numbers of individual in two marginal parts were smaller than that in center in same D. smilacinum patch. And the total numbers of individuals grown in (10 ${\times}$ 10)cm were from 0 to 12. The rhizome (subterranean runner) weight, rhizome length, root weight, shoot weight, lea weight and leaf number per subquadrat (cell) increased along the number of individual, that is, increased from marginal part to center. But rhizome weight and rhizome length per individual were vice versa. Therefore, the individuals in marginal part reproduced longer and stronger asexual propagules than that in center. The distribution pattern of D. smilacinum was contageous and that of D. viridescens was random or regular. Therefore, population growth of former was independent on density and that of latter was dependent on density. The distributions of size-class showed normal curves in two population, but the curves based on data of total dry weight showed positive skewness and those of leaf number showed negative skewness The correlation coefficient (CC) values between the properties of each organ were high in two population and significant at 0.1% level. The CC values of D. viridescens were higher of the two. Therefore, the former allocated the energy to each organ stable. The rhizome depth of d. viridescens was 2 times deeper than that of D. smilacinum. And rhizome length and weight of D. viridescens were longer (2 times) or heavier (4 times) than those of D. smilacinum. The patch size of D. viridescens increased 60 cm per year and that of D. smilacinum 30 cm. On this results, the intrinsic increase velocity of d. viridescens patch was 2 times faster than that of d. smilacinum, therefore, on the competition, the former had an advantage over D. smilacinum. The reason why d. viridescens defeated D. smilacinum resulted from that the leaf area of former was 4 times broader than that of latter. in Mt. Nam Park, it was thought that two disporum Population would change with the 3 thpes of environmental change as followings. First, no human impact and increase of soil moisture content resulted in increase of D. viridescens population. Second, mild human impact and similar condition of soil moisture content resulted in slow increase or no changes of D. smilacinum and d. viridescens population. Third, severe human impact and dry condition resulted in decrease or vanishment of two disporum populations.

• 한국유변학회:학술대회논문집
• /
• 한국유변학회 2006년도 춘계 학술발표회 논문집
• /
• pp.81-84
• /
• 2006

Slot coating process, in continuous and patch modes, has been applied for the many precise coating products, e.g., flat panel displays and second batteries. However, manufacturing uniform coating products is not a trivial task at high-speed operations because various flow instabilities or defects such as leaking, bubbles, ribbing, and rivulets are frequently observed in this process. It is no wonder, therefore, that many efforts to understand the various aspects of dynamics and coating windows of this process have been made both in academia and industry. In this study, as the first topic, flow dynamics within the coating bead in slot coating process has been investigated using the one-dimensional viscocapillary model by lubrication approximation and two-dimensional model by Flow-3D software. Especially, operability windows in both 1D and 2D cases with various slot die lip designs have been successfully portrayed. Also, effects of process conditions like viscosity and coating gap size on slot coating window have been analyzed. Also, some experiments to find minimum coating thickness and coating windows have been conducted using slot die coater implemented with flow visualization device, corroborating the numerical results. As the second topic, flow dynamics of both Newtonian and Non-Newtonian fluids in patch or pattern slot coating process, which is employed in manufacturing IT products such as secondary batteries, has been investigated for the purpose of optimal process designs. As a matter of fact, the flow control in this system is more difficult than in continuous case because od its transient or time-dependent nature. The internal die and die lip designs for patterned uniform coating products have been obtained by controlling flow behaviors of coating liquids issuing from slot. Numerical simulations have been performed using Fluent and Flow-3D packages. Flow behavior and pressure distribution inside the slot die has been compared with various die internal shapes and geometries. In the coating bead region, efforts to reduce irregular coating defects in head and tail parts of one patterned coating unit have been tried by changing die lip shapes. It has been concluded that optimal die internal design gas been developed, guaranteeing uniform velocity distribution of both Newtonian and shear thinning fluids at the die exit. And also optimal die lip design has been established, providing the longer uniform coating layer thickness within one coating unit.

• 대한한방소아과학회지
• /
• 제18권1호
• /
• pp.1-9
• /
• 2004

Objectives: The purpose of this study was clinical review of pediatric patients with fracture that visited oriental medicine center. Methods: In retrospective study, the pediatric patients, who were visited to oriental medicine center due to fracture, were classified by sex, age, fracture site, date of accident, injury mechanism, time of treatment, kind of treatment. Results and Conclusion: Total 32 patients were visited due to fracture from April 2001 to March 2004. Male Patients were 27, female were 5. In distribution of age, 10 year-old and 11 year-old were 40.7% of totality. In distribution of month, May was 10(31.3%), June was 6(18.8%), and March was 4(12.5%). There are more patients with fracture in spring than other season. In distribution of fracture site, foot was 15(46.9%), hand was 7(21.9%), ankle was 4(12.5%), upper extremity was 3(9.4%), clavicle was 2(6.3%), tibia was 1(3.1%). In distribution of injury mechanism, slip down was 23(71.9%), impaction 5(15.6%), fall down 3(19.4%), crushing injury 1(13.1%). In distribution of injury motive, soccer was 8(25.0%), basketball 4(12.5%), skating 3(9.4%), cycling 2(6.3%), sliding 1(3.1%), Tae-kwon-do 1(3.1%), other sports 5(15.6%), collision 1(3.1%), walking 2(6.3%), hit 3(9.4%), etc. 2(6.3%). In distribution of treatment account, one time was 23(71.9%), twice 3(9.4%), three times 2(6.3%), four times 2(6.3%), five times 2(6.3%). In distribution of treatment time, 1 week was 26(81.3%), 2 weeks 4(12.5%), 3 weeks 2(6.3%). In distribution of treatment kind, acupuncture treatment was 18(56.3%), negative cupping 7(21.9%), splint 13(40.6%), and other treatment(coban taping, medical patch, and so on) 5(15.6%), transfer 14(43.8%).

• 한국공간구조학회논문집
• /
• 제5권4호
• /
• pp.53-59
• /
• 2005

이 논문은 경계조건에 따른 판구조물의 최적두께분포 변화에 대한 연구결과를 기술하였다. 본 연구에서는 최소화하고자하는 변형에너지를 목적함수로 하고 구조물의 초기 부피 값을 제약조건으로 사용하였다. 판구조물의 두께분포를 표현하기 위하여 쿤이 개발한 조각 면을 이용하였다. 판의 변형에너지를 정확히 계산하기 위하여 퇴화 쉘 요소를 도입하였으며 반복계산을 통하여 최적의 두께분포를 검색하기 위하여 최적화검색기 DOT를 도입하였다. 마지막으로 경계조건에 따른 판의 최적두께 분포에 대한 정량적인 수치해석결과를 제공하기 위하여 정사각형 판을 최적화에 채용하고 그 결과를 자세히 기술하였다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
• /
• pp.288-295
• /
• 2003

An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the recovery technique. In case of the recovery technique, the SPR(superconvergent patch recovery) approach has been modified for p-adaptive mesh refinement. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly. To verify the proposed algorithm, the limit value approach is proposed which utilizes the exact strain energy computed from the extrapolation equation. A new pre-processor is developed for the p-version finite element program in which the vector graphic editor is used for the automatic generation of node connection and coordinate by halfedge solid data structure according to uniform or nonuniform p-distribution. The general 2-D algorithm is also developed to generate face modes and internal modes in accordance with different mesh types. The quality of the error estimator is investigated with the help of two mumerical examples. The results show that the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.387-394
• /
• 2000

Theoretical and experimental study is conducted on the contact pressure distribution of a radial tire in motion under various camber angles. Tire construction is modelled by a spring bedded elastic ring, consisted of sidewall springs and a composite belt ring. The contact area is assumed to be a trapezoidal shape varying with camber angles and weighted load. The basic equation in a quasi-static form is derived for the deformation of a running belt with a constant velocity by the aid of Lagrange-Euler transformation. Galerkin's method and stepwise calculation are applied for solving the basic equation and the mechanical boundary condition along both sides of the contact belt part subjected to shearing forces transmitted from the sidewall spring. Experimental results on the contact pressure, measured by pressure sensors embedded in the surface of the drum tester, correspond well with the calculated ones for the test tire under various camber angles, running velocities and weighted loads. These results indicate that a buckling phenomenon of the contact belt in the widthwise direction occurs due to the effect of camber angle.

• Composites Research
• /
• 제29권3호
• /
• pp.117-124
• /
• 2016

본 연구에서는 스카프 패치로 수리한 복합재 단일겹침 체결부의 파손강도를 시험과 해석으로 연구하였다. 스카프 비, 모재의 적층패턴, 결함크기를 달리 하며 총 45개의 시편에 대한 시험을 수행하여 파손강도와 파손모드를 분석하였다. 다양한 형상의 시편에 대한 시험 결과, 한 경우를 제외하고는 수리 후의 체결부가 결함이 없는 체결부 강도 이상의 강도를 회복하며, 체결부 인자에 따른 특별한 차이는 나타나지 않는 것을 확인하였다. 파손강도가 낮게 나타난 한 경우에 대한 파손면 분석결과 모재의 표면층인 평직층의 표면처리가 충분치 않은 것이 원인인 것으로 판단되었다. 시험 결과의 분석을 위해 3차원 유한요소해석을 수행하였는데, 유한요소해석에서도 고려한 체결부 인자가 상하부 모재와 패치, 접착층에서의 응력에 큰 영향을 미치지 않는 것을 확인하였다. 이는 단일겹침 체결부의 경우 외부 인장하중이 겹침영역을 통과하면서 상하부 모재로 분산되기 때문인 것으로 판단된다. 시험과 해석 결과 모재 중앙에 결함이 존재하는 단일겹침 체결부의 경우 절차에 따라 패치 접착이 이루어지고, 모재의 표면처리가 충분히 이루어진다면 수리를 통해 손상 전 강도를 회복할 수 있는 것으로 판단된다.

• 전자공학회논문지
• /
• 제51권11호
• /
• pp.146-154
• /
• 2014

텍스쳐 분류에 사용되는 방식 중 하나인 지역적 이진화 패턴은 일반적으로 영상 내의 평탄한 부분, 에지, 코너의 분포를 사용한다. 그러나 영상이 가지는 방향성을 고려하지 않고, 단순히 크고 작음만을 비교하는 지역적 이진화 패턴의 특성때문에 화소간 차이를 반영하지 못하는 문제점이 있다. 또한 영상의 분포를 사용하기 때문에 작은 크기의 영상에 대해서는 분류 성능이 저하된다. 이런 문제를 해결하기 위해 본 논문에서는 영상의 방향성 분포와 고유치 행렬을 이용한 세부 분류 기법을 제안한다. 지역적 이진화 패턴으로 초기 분류에서 누락된 텍스쳐 영상에 대하여 두 가지 특징을 이용하여 세부적으로 분류한다. 첫째, 영상이 가질 수 있는 방향을 여덟 가지로 양자화하고 그 방향들의 분포를 계산한다. 둘째, 구조 행렬을 이용하여 나온 고유치 중 큰 값의 분포를 구한다. 모의 실험을 통해 지역적 이진화 패턴만을 사용하였을 때 대비 제안 방법이 약 8% 정도 분류 정확도가 향상됨을 보였다.

• Journal of electromagnetic engineering and science
• /
• 제19권1호
• /
• pp.64-70
• /
• 2019

In this study, a compact series-fed center-fed open-stub (SFCFOS) linear array antenna for K-band applications is presented. The antenna is composed of a single-line 10-element linear array. A symmetrical Chebyshev amplitude distribution (CAD) is used to obtain a low sidelobe characteristic against a uniform amplitude distribution (UAD). The amplitude is controlled by varying the width of the microstrip patch elements, and open-ended stubs are arranged next to the last antenna element to use the energy of the radiating signal more effectively. We insert a series-fed stub between two patches and obtain a low mutual coupling for a 4.28-mm center-to-center spacing ($0.7{\lambda}$ at 21 GHz). A prototype of the antenna is fabricated and tested. The overall size of the uniform linear array is $7.04{\times}1.05{\times}0.0563{\lambda}_g^3$ and that of the Chebyshev linear array is $9.92{\times}1.48{\times}0.0793{\lambda}_g^3$. The UAD array yields a ${\mid}S_{11}{\mid}$ < -10 dB bandwidth of 1.33% (20.912-21.192 GHz) and 1.45% (20.89-21.196 GHz) for the CAD. The uniform array design gives a -23 dB return loss, and the Chebyshev array achieves a -30.68 dB return loss at the center frequency with gains of 15.3 dBi and 17 dBi, respectively. The simulated and measured results are in good agreement.