• 한국철도학회논문집
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• 제13권1호
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• pp.71-77
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• 2010

대부분의 선진국에서 교량의 유지보수 및 보강(Maintenance Repair & Rehabilitation-MR&R)으로 인한 비용은 해마다 증가하고 있다. 전산화된 교량유지관리 및 의사결정시스템(Bridge Management System-BMS)은 가능한 최저의 생애주기비용(Life Cycle Cost - LCC)에 최적의 안정성를 확보하기 위해 개발되었다. 본 논문에서는 제한된 현존하는 교량진단기록을 이용하여 현존하지 않는 과거의 교량상태등급 데이타를 생성하기 위해 Backward Prediction Model(BPM)이라 불리는 인공신경망(Artificial Neural Network-ANN)에 기초한 예측모델을 제시한다. 제안된 BPM은 한정된 교량 정기점검기록으로부터 현존하는 교량진단기록과 연관성을 확립하기 위해 교통량과 인구, 그리고 기후 등과 같은 비구조적 요소를 이용하며, 제한된 교량진단기록과 비구조적 요소 사이에 맺어진 연관성을 통해 현존하지 않는 과거의 교량상태등급 데이타를 생성할 수 있다. BPM의 신뢰도를 측정하기 위하여 Maryland DOT로 부터 얻어진 National Bridge Inventory(NBI)와 BMS 교량진단자료를 이용하였다. 이중 NBI자료를 이용한 Backward comparison 에 있어서 실제 NBI기록과 BPM으로 생성된 교량상태등급과의 차이(상판: 6.68%, 상부구조부: 6.61%, 하부구조부: 7.52%)는 BPM으로 생성된 결과의 높은 신뢰도를 보여준다. 이 연구의 결과는 제한된 정기점검 기록으로 야기되는 BMS의 장기 교량손상 예측에 관련된 사용상의 문제를 최소화하고 전반적인 BMS 결과의 신뢰도를 높이는데 기여 할 수 있다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.243-246
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• 2013

최근 우리나라 4세대 이동통신은 누구와도 고속 멀티미디어 통신 서비스가 지원하고 있다. 애플의 아이폰이 출시되면서 스마트폰에 대한 관심이 폭발적으로 증가하고 스마트폰을 활용하는 인터넷 기반 서비스가 활성화되고 있다. 스마트폰 이용자는 경제활동 인구의 대부분이 사용하고 있으며 초기형성단계를 지나 포화상태에 도달한 것으로 전문가들은 내다보고 있다. 이동통신 서비스는 1989년 아날로그 음성통화 서비스를 시작하였다. 그 후 1990년대 중반 문자메시지 전송과 디지털 음성통화 서비스가 가능한 2세대 방식이었고, 그리고 2000년 이후 저속의 데이터 서비스와 저품질의 동영상을 주고받을 수 있는 3세대 이동통신이 발전하게 되었다. 국내 이동통신은 2011년 7월 고속의 데이터 전송 속도를 제공할 수 있는 4세대 이동통신 표준방식인 LTE (long term evolution) 서비스를 상용화 하였고 현재 지속적으로 가입자가 증가하고 있다. 그런데 이러한 통신기술의 변화는 스마트폰 이용자들에게 경제적 부담을 안겨주고 있다. 따라서 본 연구의 목적은 이동통신 산업의 통신기술의 변화에 따른 통신요금 추이를 알아보고자 하였다.

• 자원환경지질
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• 제54권4호
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• pp.475-482
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• 2021

본 연구에서는 국내 석회석 노천 광산시설이나 현장에서 배출되는 광산 미세먼지의 특징과 이를 효과적으로 모니터링 할 수 있는 방안에 대해 관련 문헌 검토 및 전략을 제시하였다. 광산에서는 채굴된 광석의 파쇄와 운송 등의 공정에서 많은 양의 광산 먼지들이 발생한다. 광석에서 인위적으로 광산먼지를 생성시키는 실험를 통해 제시된 배출계수 및 관련 경험식으로 광산 시설 또는 운송 과정에서의 PM 배출량을 추정할 수 있다. 광산 PM 분산의 효과적인 모니터링을 위해 본 연구는 광산 현장의 주요 PM 배출원 주변에 여러 개의 저가 센서를 갖춘 모니터링 네트워크를 적용하였다. 따라서 본 연구에서는 시범적으로 국내 2곳의 석회석 광산 현장을 선정하여 저가의 PM 센서와 LTE(Long-Term Evolution) 데이터 통신을 통한 모니터링 네트워크를 설치하였다. 모니터링 예비 운전 결과 모니터링 기간에 따 PM 데이터는 통상적인 PM 분산 패턴을 보여주었다. 먼지 입도를 감안한 확산모델링을 PM 분산 패턴을 대략적으로 정량화할 수 있다. 또한 먼지 확산 추정을 위해서는 현장의 기상 및 지형 조건 이외에도 먼지 입도에 따른 거동을 반영한 확산 모델식을 이용하여야 한다.

• Computers and Concrete
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• 제26권4호
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• pp.309-316
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• 2020

The application of multi-variable adaptive regression spline (MARS) in predicting he long-term compressive strength of a concrete with various admixtures has been investigated in this study. The compressive strength of concrete specimens, which were made based on 24 different mix designs using various mineral and chemical admixtures in different curing ages have been obtained. First, The values of fly ash (FA), micro-silica (MS), water-reducing admixture (WRA), coarse and fine aggregates, cement, water, age of samples and compressive strength were defined as inputs to the model, and MARS analysis was used to model the compressive strength of concrete and to evaluate the most important parameters affecting the estimation of compressive strength of the concrete. Next, the proposed equation by the MARS method using particle swarm optimization (PSO) algorithm has been optimized to have more efficient equation from the economical point of view. The proposed model in this study predicted the compressive strength of the concrete with various admixtures with a correlation coefficient of R=0.958 rather than the measured compressive strengths within the laboratory. The final model reduced the production cost and provided compressive strength by reducing the WRA and increasing the FA and curing days, simultaneously. It was also found that due to the use of the liquid membrane-forming compounds (LMFC) for its lower cost than water spraying method (SWM) and also for the longer operating time of the LMFC having positive mechanical effects on the final concrete, the final product had lower cost and better mechanical properties.

• 가정과삶의질연구
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• 제27권4호
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• pp.1-18
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• 2009

This study has been performed to explore process of forming low cost small site housing communities and residential lives of the young elderly around small cities along rural counties of America and Canada, and suggest future implications for Korea. In this study, five low cost small housing zones such as cottage and mobile home parks in non-metropolitan counties of California and Ontario State such as Weed, Paradise, Sun City,, Wellington on the Lake, and Trenton were visited and the elderly residents and service experts were interviewed. The senior concentrating housing clusters were formed primarily from influx of both metropolitan and rural residents for the purpose of seeking warmful localities, traffic connections, and business purposes in theme focused production areas. On the other hand, residential lives in the zones are occasionally negatively influenced by unbalanced concentrations of elderly facilities such as nursing stations and funeral homes. For the future of Korean rural elderly policies, suggestions are made as follows: first, integrated forms of urban and rural township need to be settled as attracting places for early retiring people who seek low cost pastoral oriented but culturally activated environment. Second, a model town of mobile housing structures needs to be initiated as a measure of evaluating adaptation process of those movers. Third, a cooperation system among governmental ministries needs to be formed in order to integrate a long term master plan of establishing traditional rural town of independent housing districts. fourth, productive and active lifestyles need to be maintained for government lead retirement rural villages by limiting expansion of nursing related facilities around the independent areas. Fifth, visiting welfare service programs and volunteer groups need to be further developed for the housing area especially in winter time, when social integration and emotional comforts are extremely limited.

• 한국건설순환자원학회논문집
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• 제6권3호
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• pp.153-159
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• 2018

지하구조물에 주로 발생하는 탄산화는 콘크리트 내부의 공극수의 pH감소에 따라 부식을 유발할 수 있으므로 많은 연구가 진행되고 있다. 그러나 이산화탄소로부터 표면을 보호하는 간단한 표면 보수방법을 통하여 구조물의 내구수명의 연장이 가능하다. 기존의 결정론적 유지관리 기법과는 다르게, 확률론적 유지관리 기법에서는 내구수명의 변동성이 고려될 수 있으나 정규분포만 다루고 있다. 본 연구에서는 정규분포 이외에 로그분포를 고려할 수 있는 수명-확률분포를 유도하였으며, 이를 기초로 다양한 수명-확률분포 함수를 고려한 보수비 산정기법을 제안하였다. 제안된 기법은 초기의 내구수명 분포 또는 보수재를 통하여 연장된 내구수명 분포가 정규 또는 로그분포를 가질 경우 목표내구수명의 연장에 따라 확률론적 기법을 통하여 보수비를 평가할 수 있다. 보수를 통한 내구수명이 로그분포를 가질 경우 효과적으로 보수비를 감소시킬 수 있으며, 장기 실험 또는 실태조사를 통하여 내구수명 분포가 정의될 수 있다면 더욱 합리적인 유지관리 계획을 수립할 수 있을 것으로 판단된다.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.330-338
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• 2002

A long-term energy system in the future is expected to be based on the ideal circulation system between water and hydrogen in the sense that the hydrogen prepared from water eventually returns to water again after its use. Currently, with respect to the hydrogen energy system, it is predicted that the turning-point at which the production cost of hydrogen will become to be lower than that of fossil fuels would be after 2010. However, fuel cell technology would be able to be practically used for the applications to the transportation vehicles and small-scale power sources from 2004, and therefore, an efficient construction of the infrastructure covering hydrogen production and supply systems would be required with short-/mid-term technologies for the $CO_2$ reduction associated with fossil fuel utilization. In this paper, the hydrogen quantity available in domestic market has been estimated focusing on the hydrogen by-produced from domestic industries, and also the infrastructure for hydrogen-driven vehicles like fuel cell cars has been reviewed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.131-142
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• 2000

Facility layout is the early stage of system design that requires a mid-term or long-term plan. Since improper facility layout might incur substantial logistics cost including material handling and re-installment costs, due consideration must be given to decisions on facility layout. Facility layout is concerned with low to arrange equipment necessary for production in a given space. Its objective is to minimize the sum of all the products of each equipment's amount of flow multiplied by distance. Facility layout also is related to the issue of NP-complete, i.e., calculated amounts exponentially increase with the increase of the number of equipment. This study discusses Hybrid GA developed, as an algorithm for facility layout, to solve the above-mentioned problems. The algorithm, which is designed to efficiently place equipment, automatically produces a horizontal passageway by the block, if a designer provides the width and length of the space to be handled. In addition, this study demonstrates the validity of the Algorithm by comparing with existing algorithms that have been developed. We present a Hybrid GA approach to the facility layout problem that improves on existing work in terms of solution quality and method. Experimental results show that the proposed algorithm is able to produce better solution quality and more practical layouts than the ones obtained by applying existing algorithms.

• Asian Journal of Atmospheric Environment
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• 제12권2호
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• pp.87-108
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• 2018

Schools are one of the critical social infrastructures in a society, the first place for social activity and the most important indoor environment for children besides the home. Poor IAQ in classrooms can increase the chance of long-term and short-term health problems for students and staffs; affects productivity of teachers; and degrade the student learning environment and comfort levels. The primary objective of this paper is to review and summarize available scientific evidence on indoor air quality of schools and related health effects in children. It was found that the indoor air pollutant levels in school buildings varied over a wide range in different parts of the world depending on site characteristics, climatic conditions, outdoor pollution levels, occupant activities, ventilation type and building practices. Among the indoor air pollutants, particulate matter concentrations were found to be very high in many schools. Outdoor pollutant sources also play a major role in affecting the IAQ of the school building. Hence, scientific knowledge on sources of indoor pollutants, quantification of emissions, temporal and spatial dispersion of pollutants, toxicological properties, chemical and morphological characteristics of the pollutants and associated health risk among children in the school buildings are essential to evaluate the adequacy and cost effectiveness of control strategies for mitigating the IAQ issues.

• 대한방사선기술학회지:방사선기술과학
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• 제43권5호
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• pp.389-395
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• 2020

The evaluation of radioactivated components of heavy-ion accelerator facilities affects the safety of radiation management and the exposure dose for workers. and this is an important issue when predicting the disposal cost of waste during maintenance and dismantling of accelerator facilities. In this study, the FLUKA code was used to simulate the proton treatment device nozzle and classify the radio-nuclides and total radioactivity generated by each component over a short period of time. The source term was evaluated using NIST reference beam data, and the neutron flux generated for each component was calculated using the evaluated beam data. Radioactive isotopes caused by generated neutrons were compared and evaluated using nuclide information from the International Radiation Protection Association and the Korea Radioisotope association. Most of the nuclides produced form of beta rays and electron capture, and short-lived nuclides dominated. However, In the case of ⁵⁴Mn, which is a radioactive product of iron, the effect of gamma rays should be considered. In the case of tritium generated from a material with a low atomic number, it is considered that handling care should be taken due to its long half-life.