• Journal of the Korean Geographical Society
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• v.45 no.3
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• pp.360-374
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• 2010

The distributions, factors, and vegetation covers of debris slopes and changes of debris at the eastern Ongjeom-ri, Cheongsong-gun are analyzed. The important factors influencing on the developments of the slopes are felsites having advantages to the developments of cliffs and supply of enough debris, and the relatively long days below zero temperatures promoting the physical weathering processes. The distributional areas of the slopes at southern and western slopes are more extensive than those of northern and eastern slopes due to the active water evaporation by high insolation. The Ga area at eastern Ongjeom-ri has experienced the steady decreases of area of the slopes due to the vegetation covers and shows the increasing rates of vegetation covers of $431.0m^2/yr$ as averaged values. However, it is estimated at the Na area using terrestrial LIDAR that 1 or 2 debris were moved or displaed per year in slope.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.753-758
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• 2017

The ray-shooting problem is to find the first intersection point on the surface of given geometric objects where a ray moving along a straight line hits. Since rays are usually given in the form of queries, this problem is typically solved as follows. First, a data structure for a collection of objects is constructed as preprocessing. Then, the answer for each query ray is quickly computed using the data structure. In this paper, we consider the ray-shooting problem about the set of vertical line segments on the x-axis. We present a new data structure called a convex layer tree for n vertical line segments given by input. This is a tree structure consisting of layers of convex hulls of vertical line segments. It can be constructed in O(n log n) time and O(n) space and is easy to implement. We also present an algorithm to solve each query in O(log n) time using this data structure.

• Journal of IKEEE
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• v.23 no.4
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• pp.1236-1242
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• 2019

Recently, according to improvement of robot technology, research for mobile robot is increasing. Mobile robot having 2-wheels or 4-wheels is easy for straight driving but is difficult for direction change and rotation. So, ball robot having one contact point with base is interested by researchers. By characteristics of the one contact, ball robot is required the balancing and driving control. In this paper, smart phone application, which is usable for control by wireless communication, is proposed. The ball robot having the proposed smart phone application is designed and manufactured. Balancing and driving control by wireless communication is conducted. From the test, it is conformed that ball robot has the control performances as roll angle error is ±0.8deg, pitch angle error is ±0.7deg, x-axis position error is ±0.1m, and y-axis position error is ±0.08m for 1m driving control.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.111-121
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• 1993

Changes in bed forms and subsequent changes in channel roughness by changes in water discharge are discussed with the field data collected from some alluvial rivers in Korea. This study is limited to the following condition of river flow: (1) Medium size alluvial rivers with their widths of 100 m more or less, (2) Straight and prismatic river reach with no additional causes for energy loss but bed friction, (3) Lower-flow regime with Froude number less than 0.5. Major conclusions obtained from this study can be summarized as follows: (1) For the channels considered in this study, the bed roughness expressed by Manning's n increases from 0.02 for the plane beds with no sediment motion to 0.05 for the dune beds, (2) The roughness coefficient for alluvial channels should not be estimated from Strickler-type equations developed for the fixed beds, (3) The method for determining the channel roughness suggested in the present guideline for river works, River Structure Standard, appears to be lack of generality. More research based on the field data collected in Korea is needed in order to improve the existing methods.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.458-463
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• 1988

The solubility parameter theory for retention behaviors of phenols in a reversed phase liquid chromatography can be applied to limited ranges of the aqueous solvent system. The many examples of the exception to this theory were found to show no agreement with the retention behavior of phenols. Therefore, a new solute-solvent interaction parameter, ${\delta}_{im}$ is added to the Schoenmakers equation of the solubility parameter theory in LC to approach the equation to the real one. The new solute-solvent interaction pararneter, ${\delta}_{im}$ depends on the kinds of solvent, the solvent composition and the structure of solutes. The parameter, ${\delta}_{im}$ has the linear relationship with the solubility parameter of mobile phase, ${\delta}_{im}$. The prediction of retention behavior by this modified equation turns out to be greater than the previous one.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.73-82
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• 2010

Door is an important object to understand given environment and it could be used to distinguish with corridors and rooms. Doors are widely used natural landmark in mobile robotics for localization and navigation. However, almost algorithm for door recognition with camera is difficult real-time application because feature extraction and matching have heavy computation complexity. This paper proposes a method to recognize a door in corridor. First, we extract distinguished lines which have high possibility to comprise of door using Hough transformation. Then, we detect candidate of door region by applying previously extracted lines to first-stage visual fuzzy system. Finally, door regions are determined by verifying knob region in candidate of door region suing second-stage visual fuzzy system.

• Journal of Environmental Health Sciences
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• v.18 no.2
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• pp.102-105
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• 1992

Introduction : Isothiazolinone product is one of new preservatives used in cooling tower, paper mill, and general industrial waters.l) It is also effective in controlling bacteria and fungi in the manufacture and storage of dispersed pigments, such as kaolin clays, titanium dioxide, calcium carbonate and others\ulcorner Its broad-spectrum activity, excellent physical and chemical compatibility with anionic, nonionic and cationic surfactants and most organic and inorganic compounds and low toxicity at recommended use levels provide formulators with an effective, economical, and environmentally acceptable alternative to other commercial biocides. It dose not contain or generate formaldehyde and is easy to formulate (1.5% solution is supplied as an aqueous solution), so that it gains advantage over the other preservatives. The active ingredients of the isothiazolinone product are unchlorinated compound (2-methyl-4-isothiazolin-3-one) and chlorinated one (5-chloro-2-methyl-4-isothiazolin-3-one). Methods preferred for the analysis of preservatives are chromatographic methods, especially high performance liquid chromatograph (HPLC). Although several methods were satisfactory in respect to separation, no offical method has been published for the isothiazolinone components. This study was performed to search for an alternative method in order to show flexible operating conditions of HPLC and to reduce assay time.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.171-181
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• 2013

The radial mapping rule in bounding surface model was experimentally investigated by analyzing the drained stress probe tests on Chicago clays. The experimental data obtained from 10 drained stress probe paths were analyzed to calculate the directions of the plastic strain increments. The anisotropic bounding surface model was adopted to represent a bounding yield surface which resides in the pre-consolidation yield stress of undisturbed clays. The projection origins were estimated by finding the interceptions of the straight lines passing through the current stress point and the imaginary yield stress point on the bounding surface. The results show that the projection origin is not fixed at a point but moves toward the direction of the stress probe path after it is established around the initial stress point.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.436-436
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• 2011

팔머가뭄지수(Palmer Drought Severity Index, PDSI)는 미국의 서부 캔자스와 아이오와 지역을 기반으로 Palmer(1965)에 의해 개발된 가뭄지수이다. PDSI는 가뭄을 정량적으로 표현하기 위해 제안된 최초의 포괄적인 가뭄지수라 할 수 있으며, 하나의 기상인자가 아닌 수문순환을 구성하는 여러 가지 인자들의 복합적인 작용에 의해 가뭄이 나타난다는 점에 착안하고 있다. Palmer(1965)는 캔자스와 아이오와 지역의 자료를 이용하여 산정된 수분 편차지수를 이용하여 가뭄지속기간에 대한 합을 산정하고 각각의 지속기간별로 가장 작은 값의 분포를 검토한 후 이를 기반으로 가뭄심도 분류를 위한 가뭄단계를 제시하였으며, 수분편차지수와 이전 월의 PDSI를 이용하여 분석 대상 월의 PDSI 산정을 위한 관계식을 유도하여 제시하였다. Palmer(1965)는 최대 가뭄지속기간에 대한 검토를 통해 유도된 가뭄지수 산정공식을 가뭄기 및 습윤기에 관계없이 동일하게 적용하였다. 그러나 습윤기의 경우 가뭄기간에 대해 분석된 직선과는 다른 패턴을 보일 수 있으며, 이로 인해 습윤 상태에 대해 산정된 지수는 실제 상황과 다른 결과를 나타낼 가능성이 있다. Wells 등(2004)은 이러한 점을 고려하여 가뭄기와 습윤기에 대한 지속기간별 최대 수분편차지수의 합을 도시한 결과를 나타낸 후 가뭄기와 습윤기의 특성이 다르게 나타남을 제시하였으며, 최종적으로 가뭄기와 습윤기에 대해 PDSI 산정공식의 지속기간 인자(duration factor)를 분리하여 산정할 수 있는 방법론을 제시하였다. 본 연구에서는 Wells 등(2004)에 의해 제시된 PDSI 산정공식 유도방법을 우리나라의 관측자료에 적용한 후 그 결과를 검토하였다. 그 결과 가뭄기의 경우 기존 Palmer(1965)의 결과와 매우 유사한 가뭄지수 산정 결과를 얻을 수 있었으나 습윤기에 대해 산정된 결과는 매우 다른 특성을 나타내고 있음을 확인하였다. PDSI는 가뭄 모니터링 및 관리를 위한 지표로 널리 이용되고 있으므로 적절치 못한 지수 값이 제시될 경우 효율적인 가뭄 대책 수립을 어렵게 하는 요소로 작용할 수 있다. 따라서 본 연구에서 제시된 결과는 가뭄관리 및 모니터링을 위해 PDSI를 이용함에 있어 보다 정확한 지표를 제공하기 위해 유용한 정보로 활용될 수 있을 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6453-6457
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• 2015

In this paper, the theoretical analysis for a solenoid with a finite length was verified by the finite element simulation. The solenoids are widely being used in the field of mechanical, industrial, medical industry due to their simple structure and fast responses. Solenoid actuators use an electromagnetic force. A magnetic field is formed around the solenoid coil when a current is applied. The magnetic force generated by the magnetic field enables an inside plunger to move linearly. The axial and radial magnetic fields (magnetic flux density, B) at a certain point were calculated from the Biot-Savart's law and compared with the simulation analysis from the ANSYS-Magnetostatic S/W. Comparison result, an error exists in the error range, and could therefore verify the accuracy.