• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.275-284
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• 2000

This study was carried out to analyze the mechanical properties of soil and the slope stability on the fill slope of forest road constructed in the regions which consist of igneous and metamorphic rock area. The results were summarized as follows. 1) Soil type by Unified Soil Classification System(USCS) was classified as SW in soil slope, GP in weathered rock slope, GP in soft rock slope for both types of parent rock, but gravelly soil slopes in igneous and metamorphic rock area were classified as SP and GW, respectively. 2) Dry unit weight was $1.34g/cm^2{\sim}1.59g/cm^2$, specific gravity 0.57~0.61, and void ratio 0.66~0.93 in the case of igneous rock area, a dry unit weight was $1.35g/cm^2{\sim}1.51g/cm^2$, specific gravity 2.67~2.77, and void ratio 0.78~1.01 in the case of metamorphic rock area. 3) The strength parameters such as internal friction angle(${\phi}$) and cohesion(c) were selected and tested for slope stability analysis. ${\phi}$ and c of soil in igneous rock area were within the range of $29.51^{\circ}{\sim}41.82^{\circ}$ and $0.03kg/cm^2{\sim}0.38kg/cm^2$, respectively, and $21.43^{\circ}{\sim}41.43^{\circ}$ and $0.05kg/cm^2{\sim}0.44kg/cm^2$ in metamorphic rock area, respectively. 4) Result of the slope stability analysis of forest road showed that, in the weathered rock slope of igneous rock and the weathered rock and soil slope of metamorphic rock area, the possibility of slope failure was high as safety factor was below 1.0.

• Journal of Wetlands Research
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• v.7 no.3
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• pp.75-85
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• 2005

The Construction of industrial complex areas means the increase of imperviousness rate and the increase of nonpoint pollutant emissions during a rainfall. Generally the retention basin can become the alternative for removing and controling these nonpoint pollutants. Recently Ministry of Environment are trying to change the purpose of retention basins from flooding control to nonpoint pollutant control. In order to propel the stormwater management program, administration plan of stormwater management is enacted in Spring, 2005. Hereafter, in a newly developing area, the best management practices should be established to control the nonpoint pollutant. Landuses of the research area are classified to the categories of the 1st manufacturing industry, metal industry, fiber and chemical product manufacturing industry, etc. Therefore, this research was performed to understand washed-off characteristics of stormwater and to suggest the controling method of nonpoint pollutants. The optimum capacity of the retention basin can be determined by analyzing the relationships among data of rainfall, runoff, washed-off pollutants from the areas. The rainfall analysis using the data of normal year, recent 2, 5 and 10 years shows that the 80% rainfall frequency was occurred on 10mm accumulated rainfall, but which is not considered the first flush effect. However, by considering the first flush effect, the appropriate treatment capacity of rainfall can be decreased to 4-5mm accumulated rainfall. Using the criteria, the optimum capacity of retention basin is determined to $12,000m^3$ in the research area. The washed-off nonpoint pollutant loading from the areas have beeb calculated to 435ton/yr for TSS, 238ton/yr for COD, 8,518kg/yr for TKN and 1,816kg/yr for TP. The mass of 78.3ton/yr for TSS, 20.4ton/yr for BOD, 128.6ton/yr for COD, 4.6ton/yr for TKN and 980kg/yr for TP can be reduced by constructing the retention basin. The sediment accumulation rate is also calculated by $6.53kg/m^2-hr$.

• The Journal of Engineering Geology
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• v.29 no.2
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• pp.85-97
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• 2019

It can be observed that steep slopes ($65^{\circ}$ to $80^{\circ}$) consist of rock masses were kept stable for a long time. In rock-mass slopes with similar ground condition, steeper slopes than 1 : 0.5 ($63^{\circ}$) may be applied if the discontinuities of rock-mass slope are distributed in a direction favorable to the stability of the slope. In making a decision the angle of the slope, if the preliminary rock mass conditions applicable to steep slope are quantitatively setup, they may be used as guidance in design practice. In this study, the above rock mass was defined as a good continuum rock mass and the quantitative setup criterion range was proposed using RMR, SMR and GSI classifications for the purpose of providing engineering standard for good continuum rock mass conditions. The methods of study are as follows. The stable slope at steep slopes ($65^{\circ}$ to $80^{\circ}$) for each rock type was selected as the study area, and RMR, SMR and GSI were classified to reflect the face mapping results. The results were reviewed by applying the calculated shear strength to the stable analysis of the current state of rock mass slope using the Hoek-Brown failure criterion. It is intended to verify the validity of the preliminary criterion as a rock mass condition that remains stable on a steep slope. Based on the analysis and review by the above research method, it was analyzed that a good continuum rock mass slope can be set to Basic RMR ${\geq}50$ (45 in sedimentary rock), GSI and SMR ${\geq}45$. The safety factor of the LEM is between Fs = 14.08 and 67.50 (average 32.9), and the displacement of the FEM is 0.13 to 0.64 mm (average 0.27 mm). This can be seen as a result of quantitative representation and verification of the stability of a good continuum rock mass slope that has been maintained stable for a long period of time with steep slopes ($65^{\circ}$ to $80^{\circ}$). The setup guideline for a good continuum rock mass slope will be able to establish a more detailed setup standard when the data are accumulated, and it is also a further study project. If stable even on steep slopes of 1 : 0.1 to 0.3, the upper limit of steep slopes is 1 : 0.3 with reference to the overseas design standards and report, thus giving the benefit of ensuring economic and eco-friendlyness. Also, the development of excavation technology and plantation technology and various eco-friendly slope design techniques will help overcome psychological anxiety and rapid weathering and relaxation due to steep slope construction.

• Journal of Cadastre & Land InformatiX
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• v.52 no.2
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• pp.53-65
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• 2022

According to the advancement of the GNSS satellite positioning system, the module of hardware and operation software reflecting accuracy and economical efficiency is implemented in the user sector including the multi-channel GNSS receiver, the multi-frequency external antenna and the mobile app (App) base public positioning analysis software etc., and the multichannel GNSS RTK positioning of the active configuration method (DIY, Do it yourself) is possible according to the purpose of user. Especially, as the infrastructure of multi-GNSS satellite is expanded and the potential of expansion of utilization according to various modules is highlighted, interest in the utilization of multi-channel low-cost GNSS receiver module is gradually increasing. The purpose of this study is to review the multi-channel low-cost GNSS receivers that are appearing in the mass market in various forms and to analyze the utilization plan of the "address information facility investigation project" of the Ministry of Public Administration and Security by constructing the multi-channel low-cost GNSS positioning module based RTK survey system (hereinafter referred to as "multi-channel GNSS RTK module positioning system"). For this purpose, we constructed a low-cost "multi-channel GNSS RTK module positioning system" by combining related modules such as U-blox's F9P chipset, antenna, Ntrip transmission of GNSS observation data and RTK positioning analysis app through smartphone. Kinematic positioning was performed for circular trajectories, and static positioning was performed for address information facilities. The results of comparative analysis with the Static positioning performance of the geodetic receivers were obtained with 5 fixed points in the experimental site, and the good static surveying performance was obtained with the standard deviation of average ±1.2cm. In addition, the results of the test point for the outline of the circular structure in the orthogonal image composed of the drone image analysis and the Kinematic positioning trajectory of the low cost RTK GNSS receiver showed that the trajectory was very close to the standard deviation of average ±2.5cm. Especially, as a result of applying it to address information facilities, it was possible to verify the utility of spatial information construction at low cost compared to expensive commercial geodetic receivers, so it is expected that various utilization of "multi-channel GNSS RTK module positioning system"

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.307-317
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• 2011

This paper is to investigate the possibility of the elastic seismic design for highrise buildings through seismic performance evaluation for potential earthquakes that wind-designed highrise buildings located in strong wind zone and low seismicity can be experienced. Highrise steel diagrid frames which is the most loved structural system in recent years were wind-designed and the substantial system overstrength due to wind design procedure is verified, For the highrise steel diagrid frames, the response spectrum analysis and the seismic performance evaluation by various soil sites were conducted. It was showed that highrise steel diagrid frames with slenderness of greater than 5.2 under strong wind and low seismic zones such as Korea peninsula can resist elastically for the 500 year return period earthquake and have the possibility of seismic design for the 2400 year return period earthquake. In the member level, highrise steel diagrid frames with slenderness of greater than 5.2 all presented the immediate occupancy level regardless of soil sites for the 500 year return earthquake and excluding the $S_E$ soil site for the even 2400 year return period earthquake. In the system level, highrise steel diagrid frames with slenderness of greater than 5.2 showed the immediate occupancy level for $S_A$ and $S_B$ soil sites and the life safety for $S_C$ to $S_E$ soil site in the 500 year return period. The seismic performance level of highrise steel diagrid frames for the 2400 year return period earthquake displayed one step lower than the 500 year return period earthquake.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.362-369
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• 2013

Two-phase flow is frequently observed in many industries such as nuclear power plants and oil transportation. Two-phase flow regime depends on the flow rates, the fluid properties and the structure of flow channels. Since the identification of the flow regime is of great importance in the system design and the safety analysis, a number of theoretical and experimental investigations have been performed. This paper presents a basic research on the characteristics of each flow regime and transition boundary in the two-phase flows. The flow regime of the upward air-water flow in the vertical tube, 30 mm in the inner diameter, is distinguished by using the high-speed camera and the Wire-mesh sensor(WMS). The identified experimental data are compared with the flow regime maps proposed by Taitel et al, Mishima and Ishii. Even though there is slight difference in the transition boundary, the experimental data show general agreement with these flow regime maps.

• Journal of Korean Society of Forest Science
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• v.75 no.1
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• pp.32-37
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• 1986

In order to get the fundamental information that could be useful to judge the potentiality of occurrence of rapid shallow landslide in the objective slope, factors selected on Jinhae regions in Korea, where many landslides were caused by heavy rainfall of daily 465 mm and hourly 52mm in August 1979, was carried out through the multiple statistics of quantification method (II) by the electronic computer. The net system with $2{\times}2cm$ unit mesh was overlayed with the contour map of scale 1:5000. 74 meshes of landslides and 119 meshes of non-landslide were sampled out to survey the state of vegetative cover and geomorphological conditions, those were divided into 6 items arid 27 categories. As a result, main factors that would lead to landslide were shown in order of vegetation, slope type, slope position, slope, aspect and numbers of stream. Particularly, coniferous forest of 10 years old, concave slope and foot of mountain were main factors making slope instability. On the contrary, coniferous forest of 20-30 years old, deciduous forest, convex slope and summit contributed to the stable against Landslide. The boundary value between two groups of existence and none of landslides was -0.123, and its prediction was 72%. It was well predicted to divide into two groups of them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.363-375
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• 2013

Today, a shortage of the skilled operator has been intensified gradually and the necessity of an earthwork in extreme environment operators are difficult to access is increasing for the purpose of resource development and new living space creation. For this reason, an effort to develop an unmanned excavation robot for fully automated earthwork system is continuing globally. In Korea, a research consortium called 'Intelligent Excavation System' has been formed since 2006 as a part of Construction Technology Innovation Program of Ministry of Land, Transport and Maritime Affairs of Korea. Among detailed technologies of the Task Planning System is one of the core technologies of IES, this paper explains research and development process of the Local Area Design Module, which provides informatization unit to create automated excavators' work command information at operation level such as location, range, target, and sequence for excavation work. Designing of Local Area should be considered various influential factors such as excavator's specification, working mechanism, heuristics, and structural stability to create work plan guaranteed safety and effectiveness. For this research, conceptual and detail design of the Local Area is performed for analyzing design element and variable, and quantization method of design specification corresponding with heuristics and structural safety is generated. Finally, module is developed through constructed algorithm and developed module is verified.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.91-100
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• 2010

Existing traffic safety studies have focused on identifying the relationship among roadway crashes, highway design and incremental weather condition such as rainy/ice weather. However, it is hard to find researches that studied the effect of sun glare on traffic safety although there are abundant evidences demonstrating that fatal traffic crashes are attributed to the sun glare. Affecting drivers'vision particularly during the morning or the evening time when the sun positions close to the horizon, sun glare directly deteriorate drivers'judgmental capability. In this paper, we numerically analyze the effect of sun glare on the drivers'vision in time and space domains. Applied to the roadways around St Louis area in the United States, the GIS based simulation analysis identifies the time of day in a year and the segments of highways that are potentially influenced by the sun glare. This study evidentially confirms the fact that roadway bounded for West and East directions have longer time influenced by sun glare particularly during Spring and Fall season than other roadways. The computational result provides risky time periods of day at intersections or pedestrian crossings where the sun glare potentially endangers traffic safety, which be utilized to reduce the crashes due to the sun glare.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.197-205
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• 2015

Offshore structures for the gas production are exposed to the risk of gas leaks, and gas explosions can result in fatal damages to the primary structures as well as secondary structures. To minimize the damage from the critical accidents, the study of the dynamic response of structural members subjected to blast loads must be conducted. Furthermore, structural dynamic analysis has to be performed considering relationships between the natural frequency of structural members and time duration of the explosion loading because the explosion pressure tends to increase and dissipate within an extremely short time. In this paper, the numerical model based on time history data were proposed considering the negative phase pressure in which considerable negative phase pressures were observed in CFD analyses of gas explosions. The undamped single degree of freedom(SDOF) model was used to characterize the dynamic response under the blast loading. A blast wall of FPSO topside was considered as an essential structure in which the wall prevents explosion pressures from the process area to utility and working areas. From linear/nonlinear transient analyses using LS-DYNA, it was observed that dynamic responses of structures were influenced by significantly the negative time duration.