• 한국멀티미디어학회논문지
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• 제23권9호
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• pp.1139-1146
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• 2020

Recently, as e-learning technology advances, interaction and data exchange between lecturers and learners have become very important. In addition, accuracy of data delivery and efficiency of system implementation should be ensured. Considering these aspects, SignalR is the most suitable communication method for constructing an audience response system in e-learning. Existing audience response systems require separate wireless devices and have problems with system compatibility. SignalR, on the other hand, is capable of operating in all environments including PC programs, web, Android, and iOS, and has an advantage of being easy to develop applications. As such, SignalR is widely used in chatting functions for small scale, real-time communication system, and it has never been used to implement an audience response system. Thus, for the first time in this paper, an audience response system using SignalR was proposed and an experiment was conducted on whether it was applicable at the e-learning education field. Therefore, from the results fo an experiment, a variety of e-learning environments can be built through the audience response system using SignalR proposed in this paper.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.1020-1025
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• 2005

The set covering(SC) problem has many practical application of modeling not only real world problems in civilian but also in military. In this paper we study optimal allocation model for maximizing utility of consolidating old fashioned and new air defense weapon system like Patriot missile and develop the new computational algorithm for the SC problem by using simulated annealing(SA) algorithm. This study examines three different methods: 1) simulated annealing(SA); 2) accelerated simulated annealing(ASA); and 3) selection by effectiveness degree(SED) with SA. The SED is adopted as an enhanced SA algorithm that the neighboring solutions could be generated only in possible optimal feasible region at the PERTURB function. Furthermore, we perform various experiments for both a reduced and an extended scale sized situations depending on the number of customers(protective objective), service(air defense), facilities(air defense artillery), threat, candidate locations, and azimuth angles of Patriot missile. Our experiment shows that the SED obtains the best results than others.

• 한국실내디자인학회논문집
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• 제38호
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• pp.225-232
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• 2003

The purpose of this study is to select the optimal and minimum transmittance for visual amenity in office buildings. This study progressed as follows. The first, we select 5 films with various transmittance based on the current film makers whose films being used on the windows of office building nowadays and the case study of construction. And then we choose 6 kinds of transmittance as evaluation object including plain glass. The second, we made a mock-up models having different transmittance on the southern windows with model of real scale office building. The third, we select 17 pairs of adjectives for the evaluation of visual comfort on interior or exterior conditions with transmittance factor. The fourth, subjective evaluation experiment was done using selected evaluation adjectives and the result was analyzed. The results are as follows : the minimum transmittance appropriate for the office building is 30%∼40% and the optimal transmittance range is 40%∼60%.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.209-212
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• 2000

As a bench-scale study, transformation of nitrate to nitrogen gas under anoxic condition was determined by using autotrophic denitrifiers containing Thiobacillus denitrificans and elemental sulfur as an electron donor. The research objective is to measure the basic kinetic parameters of autotrophic denitrification reaction on the removal efficiency of nitrate. The results showed that nitrate was almost completely transformed to nitrite in the first 4 days of column operation. After 2 days of accumulation of nitrite, its concentration slowly decreased and the compound was detected less than 0.5 mg/L in 14 days. In the experiment, sulfate concentration in the effluent was the 70~90 mg-S/L and the pH was maintained around pH 7.5. When nitrate concentration of bank filtrate in the real field is considered, this sulfate concentration seems to be acceptable. At 17 cm from the bottom of the column, the effluent showed the highest nitrite concentration, and nitrate concentration decreased rapidly to the Point of 33 cm from the bottom. The results suggest that an appropriate thickness of permeable reactive barriers is about 30 cm.

• Structural Engineering and Mechanics
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• 제50권1호
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• pp.89-103
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• 2014

According to experimental studies made so far, design formula of shear characteristics suggested by ISO 22762 and JEAG 4614, representative design code for Lead Rubber Bearing(LRB) shows dependence caused by changes in compressive stress. Especially, in the case of atypical special structure, such as a nuclear power structure, placement of seismic isolation bearing is more limited compared to that of existing structures and design compressive stress is various in sizes. As a result, there is a difference between design factor and real behavior with regards to shear characteristics of base isolation device, depending on compressive stress. In this study, a full-scale low hardness device of LRB, representative base isolation device was manufactured, analyzed, and then evaluated through an experiment on shear characteristics related to various compressive stresses. With design compressive stress of the full-scale LRB (13MPa) being a basis, changes in shear characteristics were analyzed for compressive stress of 5 MPa, 10 MPa, 13 MPa, 15 MPa, and 20 MPa based on characteristics test specified by ISO 22762:2010 and based on the test result, a regression analysis was made to offer an empirical formula. With application of proposed design formula which reflected the existing design formula and empirical formula, trend of horizontal characteristics was analyzed.

• 한국통신학회논문지
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• 제32권12B호
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• pp.758-766
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• 2007

클라이언트-서버 구조의 스트리밍 시스템은 서버의 가용 능력에 따라 클라이언트의 개수가 제한되는 단점을 가지고 있다. 본 논문에서는 인터넷 방송 시스템의 확장성과 안정성을 지원하기 위해 P2P에 기반한 모델을 제시한 후, 프로토타입 시스템을 구현한 사례를 소개한다. 본 논문에서 구현한 시스템인 OmniCast264는 실시간으로 H.264 비디오 스트림을 제공하는 인코딩 서버, 스트림을 네트워크에 분배하는 스트리ald 서버, 비디오의 재생 및 분배를 담당하는 피어 노드, 그리고 P2P 네트워크에 노드를 동적으로 배치시키는 프록시 서버로 구성된다. P2P에기반한 OmniCast264은 스트리밍 부하의 분산화, 실시간 재생, 에러 발생에 따른 강건함, 계층의 모듈화 등의 개념을 가지고 있기 때문에 대용량의 인터넷 방송에 적합하다고 할 수 있다. 마지막으로 12 대의 PC들을 병렬 및 직렬 구조의 P2P로 구성한 후, OmniCast264의 성능을 평가하여 실시간 재생이 가능함을 검증하였다.

• 대한토목학회논문집
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• 제31권2D호
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• pp.185-192
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• 2011

시간개념을 고려한 교통 분석은 교통류의 이동을 고려함으로써 보다 현실적인 분석 결과를 가져올 수 있다. 본 논문은 실제 개인의 통행기록 자료를 활용하여 고속도로 Corridor를 대상으로 한 시간대별 기종점 통행량 구축 방법론을 개발하였다. 실제 개별 통행기록 자료인 고속도로 TCS 자료를 활용하여 전국 고속도로망을 대상으로 시간대별 O-D를 구축하였으며, 도심지역 분석에 활용도를 높이기 위해 구축된 시간대별 O-D를 Sub-corridor 시간대별 O-D로 전환하기 위한 방법론을 개발하였다. 본 연구는 실제 통행 자료를 활용한 기종점 통행량 구축이라는 점에서 의미를 가지며, 향후 고속도로 이외의 도로를 포함한 동적 기종점 통행량 구축에 관한 연구 및 기존의 통계적 추정을 이용한 O-D 구축방법과의 연계를 통해 교통분석의 주요 입력 자료인 동적 기종점 통행량의 구축이 가능할 것으로 기대한다.

• 한국수자원학회논문집
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• 제54권3호
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• pp.181-190
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• 2021

본 연구에서는 하천에서의 월류 발생에 따른 제방의 붕괴를 방지하거나 피해를 최소화하기 위한 신소재 보강공법을 제체 표면에 적용하여 그 효과를 검증하기 위한 실규모 횡월류 붕괴 실험을 수행하였다. 본 실험을 위해 제방 모형은 높이 2.5 m, 길이 12 m, 사면경사 1:2로 구성하였다. 또한 제방의 경우 습식 공법을 이용하여 바이오폴리머 분말, 물, 화강풍화토, 황토를 적정 비율로 혼합한 신소재를 제체 표면에 약 5 cm 두께로 분사한 뒤 식생활착 모니터링을 거쳐 최종 실험모형을 완성하였다. 안동하천연구센터 A3 수로 상류에서 4 ㎥/s 의 유량을 유입시켜 횡월류 흐름을 유도하였으며, 음향 도플러 유속계를 이용하여 상·하류의 유량 및 횡월류량의 변동을 측정하였다. 또한, 제방보강공법의 성능을 평가하기 위해 이미지 픽셀 기법 및 3차원 포인트 클라우드 모델링 기법을 활용한 시간에 따른 제방의 표면손실률을 산정함으로써 영상분석 기반의 새로운 평가 도구를 제시하였다. 본 연구결과를 적절하게 활용하게 되면 제방보강공법의 성능을 평가하는데 기초 자료로 활용될 수 있을 것으로 사료된다.

• 한국안전학회지
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• 제21권5호
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• pp.6-11
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• 2006

This study aims to measure a smoke density and velocity by using the PIV method in case a fire occurs in tunnels. By doing so, this will estimate a critical velocity, examine its appropriateness, and present the basic materials necessary for designing a smoke control equipment. For this study, a visualization test was conducted based on the 1/20 miniature of a real tunnel according to the Froude scaling. As a part of basic experiments, a correlation between smoke density and brightness was analyzed here, and a critical velocity was estimated on the condition that a fire breaks out in tunnels. As a result, this study finds that there is a correlation between smoke density and brightness within a range of 100% to 30% transmittance, from which a quantitative smoke density can be obtained. The study also suggests that a critical velocity calculated from the Kennedy formula shows about 10% difference from that estimated in the test.

• 국제강구조저널
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• 제18권4호
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• pp.1177-1190
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• 2018

This study presents an analytical framework for estimating the thermo-mechanical behavior of a composite beam exposed to fire. The framework involves: a fire simulation from which the evolution of temperature on the structure surface is obtained; data transfer by an interface model, whereby the surface temperature is assigned to the finite element model of the structure for thermo-mechanical analysis; and nonlinear thermo-mechanical analysis for predicting the structural response under high temperatures. We use a plastic-damage model for calculating the response of concrete slabs, and propose a method to determine the stiffness degradation parameter of the plastic-damage model by a nonlinear regression of concrete cylinder test data. To validate simulation results, structural fire experiments have been performed on a real-scale steel-concrete composite beam using the fire load prescribed by ASTM E119 standard fire curve. The calculated evolution of deflection at the center of the beam shows good agreement with experimental results. The local test results as well as the effective plastic strain distribution and section rotation of the composite beam at elevated temperatures are also investigated.