• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.461-461
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• 2016

이상기후로 인하여 제방붕괴에 대한 위험성이 높아지고 있고, 이로 인해 발생하는 제내지 내 붕괴 홍수파에 대한 연구가 증가하고 있다. 특히 홍수파 선단의 이동 속도 추정은 제내지의 위험성을 예측하고, EAP 등을 수립하는데 매우 중요한 자료가 될 수 있다. 제내지에서의 선단 홍수파에 대한 예측을 하기 위해서는 해당 지역의 하천특성, 수리특성 및 제방 등 수공구조물 특성뿐만 아니라, 제내지의 지형 및 토지이용 현황 등을 조사하여 수리실험이나 수치모의를 수행해야 하는 것이 일반적이다. 수치해석의 경우 수리실험에 비하여 경제성 및 효율성 측면에서 뛰어날 수 있으나, 제방 붕괴과정 및 메커니즘을 반영하기가 불가능하다. 이에 반해 수리모형실험의 경우 제방붕괴 양상 및 그 과정의 재현이 가능하기 때문에, 제내지에서의 선단홍수파 전파에 관한 보다 정확한 양상을 파악할 수 있을 것이다. 그러나 이러한 실험은 실제 크기의 하천이 아닌 축소모형 또는 개수로에서 수행되었기 때문에, 초기 홍수파의 전파가 축척효과(Scale effect)의 영향을 받을 가능성이 매우 크다. 특히 선단 홍수파의 경우 파가 진행되면서 수심이 낮아지고, 유속이 느려지기 때문에 그 영향은 점차 증대된다고 할 수 있다. 이에 본 연구에서는 이러한 초기 선단 홍수파의 표면장력 영향을 고려한 보정 계수 산정에 대한 연구를 수리실험을 통해 수행하였다. 연구는 크게 4가지 과정으로 구성되었다. 첫째는 농도-표면장력의 관계 규명이며, 둘째는 표면장력-홍수파 전파 속도 관계 규명이다. 셋째는 표면장력과 Weber Number(We)의 관계를 도출하는 것이며, 마지막은 We를 이용하여 한계조건을 제시하는 것이다. 실험은 계면활성제의 농도를 변화시켜가며, 얇은 유리관(D=1.0 mm)에서 물의 상승 높이 및 접촉각을 측정하여 농도와 표면장력의 관계를 측정하였으며, 이러한 결과를 바탕으로 물의 표면장력을 변화시켜 가며 $0.5(B){\times}0.3(L){\times}0.2(H)m$의 Head-tank에 설치된 수문을 빠르게 개방하여, 홍수파가 퍼지는 양상을 관측하였다. 홍수파의 이동 속도는 진행시간에 따라서 퍼짐 넓이를 측정하여 제곱근을 취하는 방식으로 평균속도를 산정하였다. 이러한 관계를 이용하여 표면장력이 없을 경우의 이동속도 및 ??를 도출하였다. 본 연구를 통해 홍수파 전파 특성에 대한 수리실험 자료를 바탕으로 Weber 수를 도출하여 표면장력의 영향을 받는지 여부를 판단할 수 있으며, 표면장력의 영향을 받을 경우, 제시된 결과를 이용하여 홍수파 선단의 속도를 보정할 수 있다. 본 연구 결과는 토대로 축소모형으로 수행되는 홍수파 전파에 대한 수리실험결과의 보정 기초자료로 매우 유용할 것으로 판단된다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.4
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• pp.275-278
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• 2006

Google Earth enables people to easily find information linked to geographical locations. Google Earth consists of a collection of zoomable satellite images laid over a 3-D Earth model and any geographically referenced information can be uploaded to the Web and then downloaded directly into Google Earth. This can be achieved by encoding in Google's open file format, KML (Keyhole Markup Language), where it is visible as a new layer superimposed on the satellite images. We used KML to create and share fine resolution gridded temperature data projected to 3 climatological normal years between 2011-2100 to visualize the site-specific warming and the resultant earlier blooming of spring flowers over the Korean Peninsula. Gridded temperature and phonology data were initially prepared in ArcGIS GRID format and converted to image files (.png), which can be loaded as new layers on Google Earth. We used a high resolution LCD monitor with a 2,560 by 1,600 resolution driven by a dual link DVI card to facilitate visual effects during the demonstration.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.2
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• pp.1-11
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• 2023

This study intended to develop a technique for quantitatively and 3-dimensionally predicting the potential failure zone and impulse that may occur when trees are fall down. The main outcomes of this study are as follows. First, this study established the potential failure zone and impulse calculation formula in order to quantitatively calculate the risks generated when trees are fallen down. When estimating the potential failure zone, the calculation was performed by magnifying the height of trees by 1.5 times, reflecting the likelihood of trees falling down and slipping. With regard to the slope of a tree, the range of 360° centered on the root collar was set in the case of trees that grow upright and the range of 180° from the inclined direction was set in the case of trees that grow inclined. The angular momentum was calculated by reflecting the rotational motion from the root collar when the trees fell down, and the impulse was calculated by converting it into the linear momentum. Second, the program to calculate a potential failure zone and impulse was developed using Rhino3D and Grasshopper. This study created the 3-dimensional models of the shapes for topography, buildings, and trees using the Rhino3D, thereby connecting them to Grasshopper to construct the spatial information. The algorithm was programmed using the calculation formula in the stage of risk calculation. This calculation considered the information on the trees' growth such as the height, inclination, and weight of trees and the surrounding environment including adjacent trees, damage targets, and analysis ranges. In the stage of risk inquiry, the calculation results were visualized into a three-dimensional model by summarizing them. For instance, the risk degrees were classified into various colors to efficiently determine the dangerous trees and dangerous areas.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.101-101
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• 2011

현재 국내에서 시행되고 있는 '4대강 살리기 사업'은 하천에서 발생하는 홍수 및 가뭄재해방지를 위한 다양한 공학적 노력을 시도하고 있다. 특히 안정적인 수위 및 유량확보와 홍수방지를 위한 보(weir)가 4대강 유역에 16개 설치되고 있다. 이러한 보 구간에는 고정보와 가동보가 복합적으로 설치되고 있으며 가동보는 그 형상과 운영방식에 따라 다양한 설계방안이 적용되었다. '4대강 살리기 사업' 중 낙동강 23공구의 강정보 공사 구간에는 원호형태의 측면 형상을 갖는 라이징 섹터게이트(Rising sector gate)가 적용되었다. 라이징 섹터게이트는 구조물의 높이가 낮고 수문의 개폐장치가 수문피어 구조물 내에 설치되어 경관이 우수하며, 구조가 간단하여 비체와 수류의 안정성이 뛰어나기 때문에 4개의 공사구간에 적용되었다. 따라서 본 연구에서는 강정보의 가동보 구간 2문 중 1문을 1/100 축척으로 제작하여 가변경사 개수로에 설치하고, 홍수 빈도별 상류 유량 조건과 하류단 수위조건으로 케이스를 정하여 실험을 수행하였다. 본 실험에서 사용한 개수로 장치는 너비 0.6 m, 높이 0.8 m, 그리고 길이 15.0 m(측정가능 구간, 헤드탱크와 테일게이트 부제외)의 개수로 실험장치이다. 측부는 모두 강화유리로 되어 육안관찰 및 계측 시 용이하게 제작되었으며, 순환식 유량 공급장치를 구축하여 수로의 하부에 설치된 유량탱크로부터 계속적으로 순환하도록 설계되었다. 또한 수로 하단으로부터 상단방향으로 약 33 m 지점에 전동 유압식 Jack screw 2기가 설치되어 경사도를 조절할 수 있도록 제작되었다. 유량조절용 판넬의 제어기판에는 디지털 경사계가 설치되어 있기 때문에 보다 정확한 경사도의 조절이 가능하다. 보 모형의 총연장은 53 cm이며 폭은 45 cm이다. 섹터게이트의 게이트부분은 직경 15 cm로 설계하였다. 문주부분을 포함한 모든 모형은 아크릴로 제작하며 레이저의 주사를 방해하지 않으며 투과율을 최대로 할 수 있도록 고강도의 아크릴을 가장 얇게 하여 중공형태를 채택하였다. 실험조건은 우선 보의 운영방안에 따라 게이트의 4가지 개방도를 설정하였고, 특히 평수위조건에서는 보의 상류부에 퇴적된 퇴적물의 세척을 위한 flushing 운영개방도 포함되어 있다. 홍수시에 대한 유량조건은 2년 빈도에 해당하는 유량을 수문의 비율과 상사법칙에 따라 설정하였으며 하류단 수위조건도 동일한 조건에 대한 값을 채택하여 적용하였다. 유동장의 해석을 위해서는 비접촉식 계측방법인 PIV(Particle Image Velocimetry) 시스템을 채택하여 2차원(x-z 방향) laser sheet를 생성하고 주입된 particle에서 반사된 변위(displacement) 정보를 상호상관(cross-correlation)기법으로 유동장을 계산하였다. 또한 수리모형과 동일한 지형격자를 구축하여 3차원 CFD 프로그램인 FLOW-3D로 계산하여 결과를 비교하였다. 특히 flushing 운영방안에 대한 게이트부의 개방도를 세가지(30, 45, $60^{\circ}$)로 구분하여 모의하였고, 적절한 개방도를 제안하고자 하였다. 실험결과는 우선 4가지 운영방안에 대한 가동보 주변에서의 유속장을 파악하였고, 최대유속의 발생위치의 변화를 확인할 수 있었다. 그리고 이에 따른 보의 바닥에서 최대유속이 발생할 경우, 하상보호공 위치와 거리 등에 대해서 분석하였다. 이를 통해 가동보 운영에 따른 다양한 유속구조를 파악할 수 있게 되며 구조적 안정성 확보를 위한 검증자료로 활용될 수 있을 것으로 예상된다. 향후, 가동보 운영방안 중 수세효과(flushing effect)에 대한 효과분석을 위해 게이트부 상류구간에 적절한 입경과 비중의 퇴적물질을 설치하는 연구와 상류부에서의 유입유사농도 및 시간변화에 따른 퇴적에 관한 연구를 수행할 계획이다.

• Journal of Korean Society of Forest Science
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• v.79 no.2
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• pp.144-161
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• 1990

Pine forest communities developed in Mt. Palgong, southeastern Korea, were studied phytosociologically, with special reference to multiple management of local forests, and were classified into two communities, Pinus densiflora - Quercus mongolica community(I : mountain forest) and P. densiflora-Climbing plants community (II : valley forest) and six subgroups accompanied by several subgroups. Judging from the coincidence method, the division of communities (vegetation units) was closely related to altitude and topography. Based on vegetation units, a vertical distribution map of pine forest communities was prepared. The species composition(%) of pine forest communities under stratification, in upper and lower tree layer, teas I higher than II, in middle and shrubs lacer II higher than I (Total : Upper 15.5%, Middle 28.4%, Lower 34.6%. Shrubs 21.5%. Sum of mean coverage%i of understory vegetation was II twice as high as I (Total. shrubs 28.4%. forbs 11.4%, Graminoids 11.8%, ferns 1.0%). Based on constance, coverage and d.b.h. class etc., an actual growth and occurrence table of tree species and understory vegetation by vegetation unity were prepared, and could assume a criterion for judging potential dominance-growth conditions.

• Geophysics and Geophysical Exploration
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• v.1 no.2
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• pp.101-109
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• 1998

Using airborne magnetic data, magnetic characteristics were studied at the Samryangjin caldera area developed in the volcanics of the Yuchon sub-basin, the south eastern part of the Gyeongsang basin. Residual magnetics, reduction to the pole, horizontal derivative, and vertical derivative maps are prepared. Using these maps, the magnetic lithofaces are zoned and the geological structures such as caldera and faults were qualitatively interpreted. In addition, the two quantitative interpretations were performed. Firstly, the forward modelling were done to the 14.5 line km crossing the caldera area to the northeast-southwest direction. Applying the 3-D Euler deconvolution method to the whole study area, the depth extent and the characteristics of the magnetic anomalous bodies were studied. According to the results, the magnetic lithofaces of the area are zoned by 4 units. In general, these are well matched with the geological distributions. But the biotite granites intruded in the northern boundary of the Samryangjin caldera show the high magnetic intensity, while the biotite granites of the other areas show the low magnetic intensity and the different magnetic lithofaces. Thus, we interpreted that the biotite granites are closely related with the volcanic activity of the Samryngjin caldera, and are intruded in the fracture zones developed along the caldera rim. The Samryangjin caldera and fault structures of the area can be easily recognized by the distinct magnetic structures from the various magnetic anomaly maps. Also the topographic characteristics well reflect these structures. The results of the forward modelling show that the magnetic basement depth of the Gyeongsang sedimentary basin is on the average about 6 km and in maximum 10 km. And the depth becomes shallower toward the caldera boundary due to the shallow intrusion of the volcanics. The results of the 3-D Euler method also show the caldera and fault structures. And the relatively shallow magnetic anomalous bodies which are related with the volcanics are generally developed to the east-west and northeast directions, while the deep magnetic anomalous bodies to the northwest direction.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.273-281
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• 2011

Purpose: In order to provide the fundamental information for the design development of RGP lenses and its clinical prescription, the corneal types of Korean twenties were analyzed according to corneal shapes, astigmatic degree, and the certain distance from the corneal apex. Methods: Corneal types of total 252 eyes in 20s were firstly classified, then their corneal radii from the certain distance from the corneal apex were measured by corneal topography and further analyzed based on the astigmatic degree. Results: Korean 20s' corneal types were classified as 14.3%(36 eyes) of round, 31.3%(79 eyes) of oval, 28.6%(72 eyes) of symmetric bow tie, 17.5%(44 eyes) of asymmetric bow tie, 8.3%(21 eyes) of irregular shapes. The round and oval typed corneas had mild astigmatic degree whereas the higher astigmatic degree in symmetric and asymmetric bow tie typed corneas were shown. The relative corneal radii of round and oval typed corneas at each distance from corneal apex were shown to consistently increase regardless of astigmatic degrees when they measured at certain distances from the corneal apex. However, the relative corneal radii of symmetric and asymmetric bow tie typed corneas within 1.0-1.5mm from the corneal apex were decreased, which showed steeper slope than it within 1.0 mm and somewhat different based on astigmatic degrees. Bigger change of corneal radii outer 3.5 mm from the corneal apex in symmetric bow tie typed corneas with astigmatism of 1.50-2.00 D and 2.25-2.75 D appeared. Conclusions: The consideration of radial change from the central cornea to peripheral cornea is necessary for manufacturing RGP lens and its prescription since they showed different change in corneal radii by corneal patterns and astigmatic degrees.

• Geophysics and Geophysical Exploration
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• v.20 no.2
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• pp.88-95
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• 2017

Chogye basin, which is surrounded by country rock, has a closed-basin form. In such a basin, incident seismic energy can form multiply reflected waves, thus causing energy concentration to occur at this closed-basin area. Microtremor measurement survey was performed at the Chogye basin, which is located in Chogye-myeon and Jeokjungmyeon, Hapcheon-gun, Gyeongsangnam-do, Republic of Korea. Microtremor data were transformed into the frequency domain, and then the horizontal-to-vertical spectral ratios (HVSR) were calculated. Fundamental resonance frequencies were estimated from the HVSR results for every observation point. Using the empirical relationship between site period and thickness for sediment sites in Korea known from the previous study, the distribution of sediment thickness of the Chogye basin was estimated from the fundamental resonance frequencies. Being compared with the mountainous rim with steep slope, the measurement points inside the basin have low values of the fundamental resonance frequency with the minimum of 1.03 Hz, which corresponds to the thickness of sedimentary layer with the maximum depth of about 100 m. A three-dimensional basin model was constructed for bedrock topography of the Chogye basin by an interpolation of basin depths estimated at each measurement site.

• The Korean Journal of Petroleum Geology
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• v.3 no.1 s.4
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• pp.1-15
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• 1995

Seismic reflection profiles and exploratory drilling well samples from the southern marginal-continental shelf basin of Korea delineate that the Tertiary sedimentary sequences can be grouped into five sequences (Sequence A, Sequence B, Sequence C, Sequence D and Sequence E, in descending order). Paleontologic data, K-Ar age datings, correlation with tuff layers and sequence stratigraphic analysis reveal that the sequences A, B, C, D and E can be considered as the deposits of Holocene $\~$ Pleistocene, Pliocene, Late Miocene, Early $\~$ Middle Miocene and Oligocene, respectively. The sequence stratigraphic and structural analyses suggest that the southern part of the Cheju Basin had experienced severe folding and faulting. NE-SW trending strike-slip movement is responsible for the deformation. The sinistral movement of strike-slip fault ceased before the deposition of Sequence B. Age dating and rare-earth elements analysis of volvanic rocks reveal+ that the Sequence D was deposited during the Early $\~$ Middle Miocene and the Sequence I was deposited earlier than the deposition of the Green Tuff Formation. Sedimentary petrological studies indicate that sediments of the Sequence I came from the continental block provenance. After the deposition of the Sequence E, uplift of the source area resulted in increase of sediment supply, subsidence and volcanic activities. The Sequence D show these factors and the sediments of the Sequence D are considered to be transported from the recycled orogenic belt.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.4
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• pp.267-285
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• 2002

Dok Island, a Pliocene volcano, lies in the southwestern part of the East Sea. Most the work to date have focused primarily on the petrolography of the island, and as a result, the morphological characteristics and internal structure of the volcanic edifices of the Dok Island remain poorly understood. To provide better constraints on these features, bathymetric data with multibeam echo sounder, 32-channel seismic and 3D gravity modeling were used in this study. Three positive topographic highs are present in the study area, and these highs satisfy the seamount criteria. They are named as Dokdo, Tamhae, and Donghae seamounts. 32-channel seismic survey was conducted to investigate the sediment thickness of the area, which shows that there are no sediments near the summit of seamounts. Away from the seamounts, however, sediment becomes thick(>2000 m) toward the western part of the study area, and sediments in the northern and southern parts are about 1000 m thick. Free-Air gravity anomalies in this study generally follow the bathymetric feature with less than -20 mGal at the western part, but increase towards the seamounts. In the summit of the Dokdo Seamount, anomalies reach over 120 mGal, and in Tamhae and Donghae seamounts, the peak anomaly shows 90 and 70 mGals, respectively. All seamounts have an isolated volcanic conduit in their centre and show regional compensation root with 0.5～1.5 km thickness. The flat-topped summit of the seamounts is probably caused by wave truncation, indicating the sea level at the time of formation of the flat-topped geometry. Comparison between the present-day sea level and subsidence level during the opening of the East Sea suggests that the seamounts in the study area have subsided by 200～300 m after the formation. Furthermore, it implies that the seamounts formed over 12～10 Ma.