• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5D
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• pp.739-747
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• 2011

The paper presents implementation & evaluation of survey method with tilted transducer of Multi Beam Echo Sounder (MBES) to increase horizontal & vertical coverage over obstructed port environments with limited physical properties of MBES. Proposed method ($25^{\circ}$ titled transducer) have some discrepancy of bathymetric profiles between normal and tilting method, but we proved average difference is less than IHO Special Order requirements with survey data at port of Dong Ho Port, Masan, Korea. For horizontal mapping coverage of total survey area ($114,961m^2$), normal method covered 53%, $60,895m^2$ of total area but tilting method covered 75%, $5.933m^2$. It is 22% efficient than normal method with similar environments. For vertical mapping coverage of total vertical structure face ($7,421m^2$), normal method covered 14%, $1,046m^2$, proposed methods covered 60%, $4,450m^2$. And we adapt longitudal steel bar to validate MBES results, and provide calibration method with titled transducer of MBES.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.259-264
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• 2014

This paper is research paper on the MPD(Magnet Position Device) for the outdoor MGV(Magnet /Magnet Gyro Guidance Vehicle). Usually, MGV is used in indoor environment because of a measurement height of the magnet position device. CMPD(Commercial magnet position device) has 30 mm measurement height, so this is suitable structure in indoor environment like to a flat surface. Outdoor environment is an uneven and irregular, So Outdoor MGV must has a suspension. But CMPD is unsuitable for outdoor environment because of a collision with a surface caused by suspension. Thus, measurement height of the outdoor MPD is positively necessary more than 100 mm. So, we suggest the outdoor MPD using analog magnet hall sensor, moving average filter and Characteristic(rate of the magnet hall sensor) function of the localization. Result of the experiments, the proposed Magnet Position Device for the outdoor MGV has localization accuracy 4.31 mm, measurement height 150 mm and width 150 mm and is efficient more than CMPD.

• Journal of Cadastre & Land InformatiX
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• v.47 no.2
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• pp.159-174
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• 2017

The long-term imbalances between supply and demand in office market can weaken urban growth since excessive supply of offices led to office market instability and excessive demand of offices weakens growth of urban industry. Recently, there have been a lot of new large-scale supplies, which increased volatility in Seoul office market. Nevertheless, new supply of Seoul office has not been fully examined. Given this, the focus of this article was on confirming the influences of profitability, replacement cost, and demand on new office supplies in Seoul. In examining those influences, another focus was on their relative influences over time. For these purposes, we analyzed quarterly data of Seoul office market between 2003 and 2015 using a vector error correction model (VECM). As a result, in terms of the influences on the current new supply, the impact of supply before the first quarter was negative, while that of office employment before the first quarter was positive. Also, that of interest rate before the second quarter was positive, while those of cap rate before the first quarter and cap rate before the second quarter were negative. Based on the findings, it is suggested that prediction models on Seoul offices need to be developed considering the influences of profitability, replacement cost, and demand on new office supplies in Seoul.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.509-517
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• 2020

This study evaluated the importance of technical characteristics in manufacturing street furniture using 3D printing technology to suggest the direction of development of high priority 3D printing technology. The importance was analyzed by the QFD, quantified by scores and the priority of the items was summarized. As a result, the 'output size', 'shrinkage of material', and 'output angle' were derived as technical elements that should be prioritized in development and research. For verification, the design of atypical street furniture was made into a large 3D printed output and the development direction was suggested by applying the technical elements of priority during the manufacturing process. Street furniture should be designed based on functionality and stability, as well as economic efficiency, productivity, and aesthetics. Therefore, the 'output size' ensured stability by minimizing the division of parts, and the 'contractability of materials' satisfied the aesthetic and productivity by minimizing the error of form. Finally, the 'output angle' was verified by improving the quality of the output and selecting an angle with efficient and structural stability through various output angles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.538-545
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• 2020

This study measured the economic impact (from 2012 through the end of 2017) of the KOR-USA FTA (Free Trade Agreement) on the Korean citrus industry according to importing orange from the USA after the implementation of the KOR-USA FTA. Citrus fruits were divided into field citrus grown in open fields, house citrus grown in green houses, and late-maturing citrus (including winter season citrus) based on the cultivation methods and the varieties of citrus. We specified the structural and dynamic recursive demand-supply equilibrium models of three citrus fruits to analyze policy simulations. The results showed that for field citrus, due to the impact of some amounts of TRQ, the annual average of the real gross revenue dropped by 2.39 billion KRW between 2012 and 2017. As for house citrus, due to the impact of oranges and cherries, the annual average of the real gross revenue declined by 3.01 billion KRW between 2012 and 2017, and for late-maturing citrus (including winter season citrus), the annual average of the real gross revenue fell by 15.11 billion KRW between 2012 and 2017. This paper also suggests several policy implications.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.6
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• pp.394-399
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• 2013

The recalcitrant hairs which are accumulated in the U-trap equipped to prevent the stench from the drainage produce the phenomenon of blocking the flow of water through the home drainage pathway. The chemical dissolution solutions commercially manufactured are excessively poured into U-trap to solve this blocking problem. In this study, the specially designed instrument was developed for the experiments to cut and crush the hairs of which main component are the recalcitrant keratin proteins. The performance of the instrument for cutting and crushing hairs was investigated using experimental methods. The cutting and weighing method was used in order to obtain the average length of a large amount of hairs cut by instrument. This method is relatively simple to measure the weight of cutting hairs to obtain the average length of the fibers, the values of average length showed not greater tolerances. Also the average cutting number was defined to evaluate the performance of the cutting and crushing instruments designed for this study. We were able to apply these evaluation methods to provide the criteria to obtain the optimal structure of instrument and proper operation time in the given experimental conditions. These experimental methods and results will provide the good example to design and to analyze the various device that can be used for cutting the fibers. The cutting and crushing instrument developed in this study showed the effective abilities to cutting the hairs. The general using the cuttting and crushing instrument at every home would be helpful to prevent water environmental pollution.

• Explosives and Blasting
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• v.18 no.2
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• pp.7-13
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• 2000

Abstract The characteristics of bed rock in the study area was classified by means of the crack coefficient estimated from the seismic velocities of in-situ and intact rocks. Various statistical methods were investigated in order to minimize the possible errors in estimating the predictive equation of blasting vibration and to enhance the determination coefficient $R^2$, for more reliable estimation. The determination coefficient showed the highest in the analysis for those groups using weighting function with the number of samples. The analysis for the weighting function employed with standard coefficient and variance also enhanced the determination coefficients significantly compared to the others, but the reliability was slightly lower than results obtained former method. Therefore the most reliable predictive equation of blasting vibration was found to be obtained from a regression analysis of the mean vibration level using the weighting of same distance groups within 15m with the same explosive charge weight per delay. The coefficients, K and n 317.4 and -1.66, respectively, when using the square root scaling, and 209.9 and -1.66, respectively, when using the cube root scaling. The analysis also showed that the square root scaling may be used in the distance less than 31m form the blast source, and the cube root scaling in the distance more than 31m for safe design.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.244-245
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• 2010

최근 광전자 분야에서는 미래 에너지 자원에 대한 관심과 함께 GaN 기반 발광다이오드 및 태양전지 연구가 활발히 진행되고 있다. GaN는 높은 전자 이동도와 높은 포화 속도 등의 광전자 소자에 유리한 특성을 가지고 있으나, 고 인듐 함유량과 막질의 우수한 특성을 동시에 구현하는 것은 매우 어렵다. 이를 극복하기 위한 방법으로써 선택 영역 박막 성장법(Selective Area Growth)은 마스크 패터닝을 통해 제한된 영역에서만 박막을 성장하는 방법으로써 GaN의 막질을 향상 시킬 수 있는 방법으로 주목받고 있다. 본 논문에서는 대면적 기판에서 GaN의 막질 향상뿐만 아니라 고인듐 InGaN 박막 성장을 위하여 서브마이크로미터 주기와 크기를 갖는 홀 패턴을 포토리소그라피 공정 최적화를 통해 구현할 수 있는 방법에 대해 논의한다. 그림. 1은 사파이어 기판 위에 선택 영역 박막 성장법을 이용하여 성장한 n-GaN/활성층/p-GaN의 구조를 나타낸 그림이다. 이를 통하여 서브마이크로미터 스케일의 반극성 InGaN면 위에 높은 인듐 함유량을 가지면서도 우수한 특성을 갖는 박막을 얻을 수 있다. 본 실험을 위하여 사파이어 기판 위에 SiO2를 증착한 후 포토레지스트(AZ5206)을 도포하고 포토리소그라피 공정을 진행하여 2um 크기 및 간격을 갖는 패턴을 형성했다. 그림. 2는 AZ5206에 UV를 조사(5초)하고 현상(23초)한 패턴을 윗면(그림. 2(a))과 $45^{\circ}$ 기울인 면(그림. 2(b)) 에서 본 SEM(Scanning Electron Microscope) 사진이다. 이를 통해 약 2.2um의 홀 패턴이 선명하게 형성 됨을 볼 수 있다. 그 후 수백나노 직경의 홀을 만들기 위해서 리플로우 공정을 수행한다. 그림. 3은 리플로우 온도에 따른 패턴의 홀 모양을 AFM(Atomic Force Microscope)을 이용하여 측정한 표면의 사진이다. 이를 통해 2차원 평면에서 리플로우 온도 및 시간에 따른 변화를 볼 수 있다. 그림.3의 (a)는 리플로우 공정을 진행하기 전 패턴이고, (b)는 $150^{\circ}C$에서 2분, (c)는 $160^{\circ}C$에서 2분 (d)는 $170^{\circ}C$에서 2분 동안 리플로우 공정을 진행한 패턴이다. $150^{\circ}C$와 $160^{\circ}C$에서는 직경에 큰 변화가 없었고, $160^{\circ}C$에서는 시료별 현상 시간 오차에 따라 홀의 크기가 커지는 경향이 나타났다. 그러나 $170^{\circ}C$에서 2분간 리플로우 한 시료 (그림. 3(d))의 경우는 홀의 직경이 ~970nm 정도로 줄어든 것을 볼 수 있다. 홀의 크기를 보다 명확히 표현하기 위해 그림.3에 대응시켜 단면을 스캔한 그래프가 그림.4에 나타나 있다. 그림.4의 (a) 및 (b)의 경우 포토레지스트의 높이 및 간격이 일정하므로, 리플로우에 의한 영향은 거의 없었다. 그림. 4(c)의 경우 포토레지스트의 높이가 그림.4(a)에 비해 ~25nm 정도 낮은 것으로 볼 때, 과도 현상 및 약간의 리플로우가 나타났을 가능성이 크다. 그림. 4(d)에서는 ~970nm의 홀 크기가 나타나서 본 연구에서 목표로 하는 나노 홀 크기에 가장 가까워짐을 확인할 수 있었다. 따라서, $170^{\circ}C$ 이상의 온도와 2분 이상의 리플로우 시간 조건에서 선택 영역 성장을 위한 나노 홀 마스크의 크기를 제어할 수 있음을 확인하였다.

• Journal of Korean Society of Transportation
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• v.21 no.2
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• pp.33-43
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• 2003

In South Korea, about 74% of total area is mountainous terrain It is therefore inevitable to make tunnel or cutting slope for road construction. According to a related survey, approximately 2,400 sites of cutting slopes were found from 24 different routes of roadway which is overall 900 km long, implying 2.7 slopes per 1km of roadway on average. Even though safety matter such as the slope failure prevention would be the most important consideration for the construction of cutting slopeslandscape of sloped face is nowadays becoming another important factor due to the growing demand for the driver-friendly road environment Various construction methods which attain this goal should therefore be considered in the design stage of the roadway. The objective of this study is to identify important factors in landscape of sloped-cut roadway using factor analysis. For this, 10 main treatment methods of sloped-cut fact were analyzed. This study employed the LISREL(structural analysis of common variance) model in order to capture the qualitative characteristics of the slope-cut road and examine the relationship between the suey error and the variable(s). As a result, more reasonable landscape evaluation model for the road design and construction was proposed.

• Journal of Korea Water Resources Association
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• v.31 no.1
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• pp.13-25
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• 1998

It is necessary to develop methodologies for the application of artificial neural network into hydrologic rainfall-runoff process, although there is so much applicability by using the functions of associative memory based on recognition for the relationships between causes and effects and the excellent fitting capacity for the nonlinear phenomenon. In this study, some problems are presented in the application procedures of artificial neural networks and the simulation of runoff hydrograph experiences are reviewed with nonlinear functional approximator by artificial neural network for rainfall-runoff relationships in a watershed. which is regarded as hydrdologic black box model. The neural network models are constructed by organizing input and output patterns with the deserved rainfall and runoff data in Pyoungchang river basin under the assumption that the rainfall data is the input pattern and runoff hydrograph is the output patterns. Analyzed with the results. it is possible to simulate the runoff hydrograph with processing element of artificial neural network with any hydrologic concepts and the weight among processing elements are well-adapted as model parameters with the assumed model structure during learning process. Based upon these results. it is expected that neural network theory can be utilized as an efficient approach to simulate runoff hydrograph and identify the relationship between rainfall and runoff as hydrosystems which is necessary to develop and manage water resources.