• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6276-6281
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• 2014

Genetic Algorithms (GAs) are efficient methods for search and optimization problems. On the other hand, there are some problems associated with the premature convergence to local optima of the multimodal function, which has multi peaks. The problem is related to the lack of genetic diversity of the population to cover the search spaces sufficiently. A sharing and crowding method were introduced. This paper proposed strategies to improve the convergence speed and the convergence to the global optimum for solving the multimodal optimization function. These strategies included the random generated sub-population that were well-distributed and spread widely through search spaces. The results of the simulation verified the effects of the proposed method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.3
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• pp.293-301
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• 2002

MGF(Marine Geographical Framework) data are the essential data sets concerning graphical and attribute information on coast and ocean among various marine-related data, which consist of framework data of the National Spatial Data Infrastructure(NSDI). This study did research and analyzed the development of current data, the situation of its usage, related technical environment and case study of foreign countries through the survey on the users and experts. Then the item of marine geographical framework data was selected in accordance with the measures for usage and management of possible MGF data. A map was pilot producted based on selected items and MGF data was presented through making up some problems shown ill the process. The importance of GIS will be growing continuously which can develop, deal with and provide the various data to efficiently manage coast and ocean. Accordingly, the MGF data will be applied to various areas such as Internet or raw data for marine information system.

• Fire Science and Engineering
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• v.18 no.1
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• pp.18-23
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• 2004

This paper describes the minimum ignition limits for propane-air 5.25 Vol.% mixture gases in low voltage inductive circiuts. The improved effects on the ignition limit are studied by parallel safety components(resistors) for propane-air 5.25 Vol.% mixture gas in low voltage inductive circuits. The experimental devices used in this test are the IEC type spark ignition test apparatus. The minimum ignition limits are controlled by the values of current in inductive circuit. Energy supplied from electric source is first accumulated at the inductance, it's extra energy is working as ignition source of the explosive gas. The improved effects on the ignition limit are respectively obtained as the maximum rising rate of 330% by composing parallel circuits between inductance and resistor as compared with disconnecting inductance with the safety components. The more values of inductance increase the higher improved effects of ignition limit rise. The less values of resistor the higher improved effects of ignition limit rise. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof machines which are applied equipment and detectors used in dangerous areas but also for datum for its equipment tests.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.150-150
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• 2015

최근 하천의 수위조절 기능을 수행하는 보 건설이 증대되고 있다. 보는 원활한 용수공급을 위해 필수적인 구조물이지만, 하천 횡단 구조물의 특성상 유사퇴적에 의한 통수단면적 감소, 홍수위험도 증가, 수질악화 등의 문제를 내포하고 있다. 이를 해결하기 위해 유사시 유사배출이 가능하고 수문개도를 통한 통수단면적 조절로 홍수위험도를 감소시킬 수 있는 가동보를 고정보와 병용해서 적용하는 추세이다. 가동보는 수문 운영 방식에 따라 하류의 흐름상태가 다양하게 나타나며, 흐름 상태에 따라 하도 및 구조물에 미치는 영향도 달라진다. 그러나 기존 가동보 및 보 하류 구조물의 설계 시 일반적으로 수문 운영조건을 고려하지 않고, 홍수위 조건을 최악조건으로 고려하는 한계가 있다. 본 연구에서는 3차원 수치모델(FLOW-3D)을 활용하여 가동보의 운영에 따라 발생하는 다양한 흐름조건이 보 하류에 미치는 영향을 검토하고자 한다. 수치모델의 검증을 위해 기존 수행된 수리실험과의 비교를 수행하였고, 홍수위 조건(수문 전문개도) 및 관리수위 조건(수문 일부개도)에서 수치모의를 수행하였다. 보 상류, 직하류, 도수종점에서 발생하는 단면최대유속, 바닥전단 응력, Froude 수 등의 수리특성을 분석하였고, 상하류간 수심차와 수문개도높이의 비와 접근유속과 보 직하류에서 유출되는 유속의 비로 무차원화하여 관계를 분석하였다. 또한 홍수위 조건과 관리수위 조건에서 발생하는 수리특성을 비교함으로써, 보 하류부 구조물 설계 시 반영할 최악조건을 예측하고, 수문운영이 하류부에 미칠 수 있는 영향을 가시적으로 확인할 수 있었다. 향후 상류의 유량조건 및 상하류 수위차에 따른 가동보의 운영조건이 보 하류의 안정성 지표산정에 활용될 수 있기 위해 보다 심도있는 연구 수행이 필요하다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.106-106
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• 2016

매립공사시 매립토의 유실로 인한 공사기간의 지연, 공사비 증액 등이 발생할 수 있다. 이에 대한 정량적인 예측은 매우 중요하나, 그에 대한 연구는 상대적으로 미비하다. 본 연구에서는 매립토의 유실은 유입된 유사와 호안 표면의 유사가 흐름에 의해 공사구간을 빠져나간 양이라 정하였다. 매립공사에서 유실량의 산정은 매립물량 산정과 직결되며 이는 경제성 부분에서 매우 중요하다. 그러나 국내에서는 경험에 의존한 유실율을 기준으로 매립물량을 결정하고 있는 실정이고, 현장계측으로도 유실량을 정량적으로 판단하기 쉽지않다. 따라서 본 연구에서는 호안 주변의 흐름 특성을 고려한 매립토의 유실량을 정량적으로 평가하기 위한 방안으로 실험적 연구를 수행하였다. 수리실험은 길이 13.0 m, 폭 5.0 m의 직사각형 단면의 광폭 수로에서 수행하였으며 일정한 양의 유사를 유입하기 위해 자체 제작한 유사공급장치를 사용하였다. 매립토의 특성을 고려하기 위하여 일반모래($d_{50}=0.621mm$, SG=2.72)와 안트라사이트($d_{50}=1.547mm$, SG=1.61) 두 가지 유사를 사용하였고, 매립토 유실요인 중 흐름특성에 의해 외부로 유실되는 양을 보다 명확히 규명하기 위해 유사를 유입하기 전과 후의 양을 각각 직접 채취하는 원시적인 방법과 3D 스캔을 통한 방법을 이용하여 평가한 유실율과 비교 검토해 보았다. 두 가지 방법에 대한 상대오차는 최대 3.12%로 나타났다. 흐름조건에 따른 매립토의 유실율은 살펴보면 두 가지 유사 모두 한계유속(Vc)을 넘어서는 순간, 급격히 유실율이 증가하였고, 일반모래는 약 10 % 안트라사이트는 약 30%로 각각 나타났다. 향후 매립토의 특성인자의 영향을 명확하게 구분하기 위해 다양한 매립토를 활용하여 보다 많은 조건하에서 실험을 수행한다면 매립토의 유실량 산정의 정확성을 높일 수 있을 것이라 기대된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.4
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• pp.149-153
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• 2019

HVPE is one of the GaN single crystal manufacturing methods which has been commercially widely used due to its high growth rate. HVPE method consists of a number of processes, in particular the nitridation of the substrate prior to GaN growth has a significant effect on the crystalline quality of the manufactured GaN single crystal. In this study, we investigated the effect of nitridation for crystalline quality of GaN when it was grown on the sapphire substrate. The whole growth conditions except for the nitridation process were the same, and the gas flow rate supplied to the sapphire substrate was variously changed during the nitridation. Here, we examined the effect of nitridation via the surface characterization of GaN single crystal grown by HVPE.

• Journal of IKEEE
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• v.23 no.1
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• pp.134-142
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• 2019

As the development of internet of energy (IoE) technologies and spread of various electronic devices have diversified patterns of energy consumption, the reliability of demand prediction has decreased, causing problems in optimization of power generation and stabilization of power supply. In this study, we propose a deep learning method, 1-Dimention-Convolution and Bidirectional Long Short-Term Memory (1D-ConvBLSTM), that combines a convolution neural network (CNN) and a Bidirectional Long Short-Term Memory(BLSTM) for highly reliable demand forecasting by effectively extracting the energy consumption pattern. In experimental results, the demand is predicted with the proposed deep learning method for various number of learning iterations and feature maps, and it is verified that the test data is predicted with a small number of iterations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.351-359
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• 2019

In order to improve the problem of parking which is getting worse day by day, the municipality carries out a survey on the actual situation of the parking lot supply and demand periodically according to the related law. However, in the existing evaluation method, the parking demand that occurs under the condition that the demand is suppressed by the parking supply and regulation due to the limit of the survey method is investigated. In addition, the analysis is conducted only for the present year, and prediction and analysis of future parking problems are limited. Therefore, we propose a method to evaluate the status of parking supply and demand, which is differentiated to improve the problem of the existing evaluation method. As a result, comparing the existing method with the improved method, it can be seen that the improved evaluation method can be useful for establishing the long-term parking policy for the improvement of parking problems.

• Journal of Digital Convergence
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• v.17 no.5
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• pp.327-332
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• 2019

The purpose of this study is to derive the differentiation and improvement measures of Kakao T through a usability evaluation centered on the service. In-depth interviews were conducted by first identifying the status of the mobility O2O service and reconfiguring the usability principles of the Honeycomb model, focusing on the functions and interfaces. First, there are problems driven from the imbalance in supply and demand as a mobility service, but it is likely to be improved through the addition of future features, carpooling. Second, problems were elicited for not recognizing the need for incorporated functions of Kakao T in the presence of existing functional-specific applications. Improvements derived based on this study are expected to help increase the convenience of users of mobility O2O services.

• Journal of Industrial Convergence
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• v.19 no.5
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• pp.1-11
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• 2021

Prior research regarding the macro patterns of industry convergence has focused on the inter-industry patent network and cross-industry movements of products or services. This article provides a novel approach, according to which human resources embodying explicit and implicit knowledge and technologies are important media driving industry convergence. Drawing on GOMS data (2015-2019) and using information of university graduates' academic majors and their occupations, this article proposes an analytic strategy by which to understand the macro patterns and structural features of industry convergence. Specifically, we build unbalanced bipartite networks of major-industry (occupation) relations, and construct the measures of the industry's niche width and the measure of the average degree of convergence of majors that each industry is linked to. By crossing the two measures, we identify four groups of industries(occupations); specialist, generalist, partial convergence, and full convergence. The convergence group is composed of industries (occupations) that acquire human resources from a number of academic majors each of which plays a role of glue connecting several local industries.