• Advances in concrete construction
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• 제15권6호
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• pp.359-376
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• 2023

Ultra-high-performance concrete (UHPC) has become an attractive cast-in-place repairing material for existing engineering structures. The present study aims to investigate age-dependent high-early-strength UHPC (HESUHPC) material properties (i.e., compressive strength, elastic modulus, flexural strength, and tensile strength) as well as interfacial shear properties of HESUHPC-normal strength concrete (NSC) composites cured at different season temperatures (i.e., summer, autumn, and winter). The typical temperatures were kept for at least seven days in different seasons from weather forecasting to guarantee an approximately consistent curing and testing condition (i.e., temperature and relative humidity) for specimens at different ages. The HESUHPC material properties are tested through standardized testing methods, and the interfacial bond performance is tested through a bi-surface shear testing method. The test results quantify the positive development of HESUHPC material properties at the early age, and the increasing amplitude decreases from summer to winter. Three-day mechanical properties in winter (with the lowest curing temperature) still gain more than 60% of the 28-day mechanical properties, and the impact of season temperatures becomes small at the later age. The HESUHPC shrinkage mainly occurs at the early age, and the final shrinkage value is not significant. The HESUHPC-NSC interface exhibits sound shear performance, the interface in most specimens does not fail, and most interfacial shear strengths are higher than the NSC-NSC composite. The HESUHPC-NSC composites at the shear failure do not exhibit a large relative slip and present a significant brittleness at the failure. The typical failures are characterized by thin-layer NSC debonding near the interface, and NSC pure shear failure. Two load-slip development patterns, and two types of main crack location are identified for the HESUHPC-NSC composites tested in different ages and seasons. In addition, shear capacity of the HESUHPC-NSC composite develops rapidly at the early age, and the increasing amplitude decreases as the season temperature decreases. This study will promote the HESUHPC application in practical engineering as a cast-in-place repairing material subjected to different natural environments.

• 한국산업보건학회지
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• 제26권2호
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• pp.139-146
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• 2016

Objectives: This study aimed to confirm the optimal processing conditions of the asbestos stabilizer by considering various actual environments at the time of stabilization treatment of the ceiling materials containing asbestos with asbestos stabilizer. Methods: The anti-scattering performances of the asbestos stabilizer were confirmed by considering the method and quantity of the asbestos stabilizer treated, comparing the loss weight by measuring the weight of ceiling materials prior to and after having treated 30, 50, 100, 200, and 400 of stabilizer using the brush and spray. The effects of backside dust and steel frame structure on the performances of the stabilizer was also confirmed by comparing samples with and without the dust on the rear surface removed by wiping the ceiling material specimens and the blinding treatment simulated by using tape. Results: The asbestos stabilization treatment using the brush method in comparison with the use of a spray has reduced stabilizer loss, resulting in better anti-scattering performance. In addition, the stabilizer loss is increased with increasing treatment quantity; as a result, treating a larger quantity of stabilizer does not improve the performance. For the conditions related to ceiling materials, the anti-scattering performance is enhanced by removing the backside dust and spreading the stabilizer evenly on the masking portion by steel frame structures. Conclusions: Based on these results, it is determined that the appropriate choice of the tool used for the treatment of the asbestos stabilizer and the appropriate quantity of asbestos stabilizer were needed at the time of actual stabilization processing of the ceiling materials containing asbestos. Moreover, this study confirmed that preliminary processing and verification of the structure at which the ceiling materials are installed can enhance the effectiveness of prevention of the scattering of asbestos into the air.

• 한국화재소방학회논문지
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• 제31권5호
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• pp.44-52
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• 2017

본 논문은 분진 색상에 따른 광전식연기감지기 챔버의 응답특성에 관한 연구이다. 국내 자동화재탐지설비 및 경보설비의 화재안전기준의 개정으로 연기감지기의 실내 적용이 의무화되었으나, 아직까지 국내에서는 실내 환경에서 발생되는 실내먼지 및 환경조건 등에 의해 발생될 수 있는 부작동 및 비화재보에 대한 연구가 미비한 편이다. 이에 본 연구에서는 실내먼지 중 가장 많이 발생될 것으로 판단되는 다양한 색상의 섬유분진에 따른 연기감지기의 실내적응성을 연구하기 위해 국내에 가장 많이 보급화 되어 있는 격자형의 연기챔버를 가진 광전식 연기감지기를 실험대상으로 하고, 갈색, 백색, 회색, 흑색 4종류의 섬유분진을 실험분진으로 하여 분진시험 및 감도시험을 진행하였다. 또한, 연기챔버의 수광부 전압을 측정하여 챔버 내부의 산란현상을 관찰하였다. 실험결과 4종류의 분진 모두 오염도 A에서는 분진시험 및 감도시험에서 모두 적합한 것으로 나타났다. 반면, 오염도 B와 C에서는 갈색, 백색, 회색분진의 경우 작동시험 및 부작동시험에서 분진오염에 의한 오작동이 나타났고, 흑색분진의 경우 작동시험에서 부작동이 발생되는 것으로 확인되었다. 연기챔버의 수광부 전압측정 결과는 갈색 및 백색분진의 경우 오염도가 증가할수록 전압이 증가하였고, 회색 및 흑색분진의 경우 전압이 감소하는 것을 확인하였다.

• 전자공학회논문지B
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• 제30B권1호
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• pp.79-89
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• 1993

This paper deals with a computer aided control of an adjustment process for the complete electronic devices by means of an application of artificial neural network and an implementation of neuro-controller for intelligent control. Multi-layer neural network model is employed as artificial neural network with the learning method of the error back propagation. Information initially available from real plant under control are the initial values of plant output, and the augmented plant input and its corresponding plant output at that time. For the intelligent control of adjustment process utilizing artificial neural network, the neural network emulator (NNE) and the neural network controller(NNC) are developed. The initial weights of each neural network are determined through off line learning for the given product and it is also employed to cope with environments of the another product by on line learning. Computer simulation, as well as the application to the real situation of proposed intelligent control system is investigated.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2661-2665
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• 2011

In order to evaluate the structural integrity of a GFRP composite bogie frame due to flying railway ballast, the low velocity impact test and compressive test after impact was conducted for glass fiber/epoxy 4-harness satin woven laminate composites applied to skin part of a bogie frame. The impact test was performed using a instrumented impact testing system with energy levels of 5J, 10J and 20J and the designed impactor based on typical railway ballast shapes such as sphere, cube and cone to simulate the ballasted track environments. The compressive strength was tested to according to ASTM D7137 to evaluate the degradation of mechanical property of impact damaged laminate composites. The results showed that the damage area and the degradation of compressive strength after impact for laminate composites was increased with increase in impact energy for all ballast shapes and was particularly most influenced by cone ballast shape.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.372-378
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• 2015

Background subtraction is the first processing stage in video surveillance. It is a general term for a process which aims to separate foreground objects from a background. The goal is to construct and maintain a statistical representation of the scene that the camera sees. The output of background subtraction will be an input to a higher-level process. Background subtraction under dynamic environment in the video sequences is one such complex task. It is an important research topic in image analysis and computer vision domains. This work deals background modeling based on modified adaptive Gaussian mixture model (GMM) with three temporal differencing (TTD) method in dynamic environment. The results of background subtraction on several sequences in various testing environments show that the proposed method is efficient and robust for the dynamic environment and achieves good accuracy.

• 대한인간공학회지
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• 제19권1호
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• pp.37-48
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• 2000

Universal design is an approach to create environments and products that recognizes the diversity of users, regardless of their ability or age. Recently, old person and disabled person rapidly go on increasing in number. So, universal design concept becomes more and more important in product and environment, etc. In this study, we dealt with the universal design problem of microwave oven considering old persons. New design model for microwave oven was developed and evaluated using human factors approach. The principles of universal design was developed through literature survey and questionnaire survey for old persons, and then design alternatives were developed according to these principles. Two experiments were performed in this study. The purpose of the first experiment was to select final design alternative and the experiment was performed using rapid prototypes. The second one was a usability testing for the real model of final alternative. In this experiment, the real model was compared with the existing real product. As the result, the new design model was a little more excellent than the existing model in usability.

• 복식문화연구
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• 제17권3호
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• pp.459-471
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• 2009

The purpose of the study is to examine the effect of VMD image appropriateness in apparel shopping contexts. Two competing models are utilized. The first model is developed from the emotion-cognition theory which explains that environmental cues(i.e., VMD image appropriateness) generate consumers' emotion, and in turn, consumers' behaviors. The second model is developed based on the cognitive theory of emotions and posits that environmental cues stimulates consumers' cognitive perceptions of retail environments, subsequently influencing consumers' emotional and behavioral response. A 2(VMD image appropriateness: high vs. low) between-subjects factorial design experiment was conducted. Female college students(n=592) participated in the experiment. Using structural equation modeling the study found that the emotion-cognition model better explains the effect of VMD image appropriateness on consumers' emotional, cognitive, and behavioral responses.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1001-1006
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• 2004

The concurrent engineering technologies have been broadly used in the field of the design, testing, manufacturing and maintenance works to reduce development time and costs. For this purpose, many design environments with the product data management system, the virtual engineering system and web database system are developed. In this research, we developed the driving simulator of the KTX(Korea Train Express) as a basic study for building the concurrent engineering design environment of rolling stock. The virtual track was developed from the Seoul to the Busan and the Daejeon to Mockpo to generate immersible driving environment. Also, fault generation systems were developed to educate drivers of the KTX. We expect to reduce the time and costs of newly developed rolling stock using the design environment developed in the research.

• 디지털산업정보학회논문지
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• 제13권1호
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• pp.13-21
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• 2017

This paper describes a design scheme of a system that tests or polls from the students at online class. By online test, the teacher can test the pre-knowledge level of the students and know how much students understand the lecture of the class. As the number of test increases, the burden of the preparation of setting question, evaluation of the test, and management of the test results is increased. In this environments, an online test management system make it easy to test and evaluate, and thus it would be a good tool for maintaining and managing the total procedure of the test or poll of the students. For evaluating the design of the system, we made a test system prototype and performed evaluations of the online test system. The online test and evaluation system provides a good tool for testing and evaluation of student's knowledge at the class with easy and fast way.