• Smart Structures and Systems
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• 제30권5호
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• pp.433-446
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• 2022

Despite efforts to reduce unexpected accidents at confined construction sites, choking accidents continue to occur. Because of the poorly ventilated atmosphere, particularly in long, confined underground spaces, workers are subject to dangerous working conditions despite the use of artificial ventilation. Moreover, the traditional monitoring methods of using portable gas detectors place safety inspectors in direct contact with hazardous conditions. In this study, a long-range (LoRa)-based wireless safety monitoring system that features the network organization, fault-tolerant, power management, and a graphical user interface (GUI) was developed for underground construction sites. The LoRa wireless data communication system was adopted to detect hazardous gases and oxygen deficiency within a confined underground space with adjustable communication range and low power consumption. Fault tolerance based on the mapping information of the entire wireless sensor network was particularly implemented to ensure the reliable operation of the monitoring system. Moreover, a sleep mode was implemented for the efficient power management. The GUI was also developed to control the entire safety-monitoring system and to manage the measured data. The developed safety-monitoring system was validated in an indoor testing and at two full-scale water pipeline construction sites.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2006년도 정기학술발표대회 논문집
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• pp.632-637
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• 2006

우리나라의 입${\cdot}$낙찰제도는 1995년 7월에 적격심사제도를 도입하기 전까지 최저가 낙찰제를 근간으로 삼아왔으며, 평균가 낙찰제나 제한적 최저가낙찰제가 보완적으로 시행되어 왔다. 하지만 최저가 낙찰제도에 의해 공사비의 직접비 수준에도 미치지 못하는 저가투찰(덤핑)이 일반화되고 부실공사에 대한 우려가 높아지면서 평균가 낙찰제나 제한적 최저가 방식이 도입되었다. 그러나 평균가낙찰제나 제한적 최저가낙찰제가 건설업체의 기술개발 노력이나 원가절감 노력을 촉진시키지 못하는 문제점이 부각됨에 따라 또다시 경쟁원리를 내세워 최저가 낙찰제로 회귀하는 악순환이 지난 50년간 반복되고 있다. 따라서 사회 ${\cdot}$ 경제적으로 급변하는 건설 환경에 대처하고 건설 산업의 구조개편에 적극 대응하여 국내 건설엔지니어링의 경쟁력을 재고하고, Global Standard와 우리나라의 실정을 모두 충족시킬 수 있는 개선방향을 해외 사례 분석을 통해 제시하고자 한다.

• Current Optics and Photonics
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• 제3권6호
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• pp.531-540
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• 2019

Spectral Amplitude Coding Optical Code Division Multiple Access (SAC OCDMA) is an advanced technique in asynchronous environments. This paper proposes design and implementation of a novel quantum logic gate (QLG) code, with code construction algorithm generated without following any code mapping procedures for SAC system. The proposed code has a unitary matrices property with maximum overlap of one chip for various clients and no overlaps in spectra for the rest of the subscribers. Results indicate that a single algorithm produces the same length increment for codes with weight greater than two and follows the same signal to noise ratio (SNR) and bit error rate (BER) calculations for a higher number of users. This paper further examines the performance of a QLG code based SAC-OCDMA system with NAND and direct detection techniques. BER analysis was carried out for the proposed code and results were compared with existing MDW, RD and GMP codes. We demonstrate that the QLG code based system performs better in terms of cardinality, which is followed by improved BER. Numerical analysis reveals that for error free transmission (10^-9), the suggested code supports approximately 170 users with code weight 4. Our results also conclude that the proposed code provides improvement in the code construction, cross-correlation and minimization of noises.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.36-37
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• 2020

The government seismic retrofit project for educational facilities is progressing more actively due to the 2018 Pohang earthquake. It is most important that seismic retrofit constructions are conformed to seismic design to achieve the desired purpose of the project as reduce direct damage caused by earthquake. However, the construction supervision system is not mandatory for the retrofit construction site of small buildings including school buildings according to applicable laws and regulations. The purpose of this study was to develop a guide for constructions management of school building seismic retrofit. In order to achieve this goal, the survey on the construction site was conducted and various problems related to the construction site of school building seismic retrofit was derived Additionally, the systematic checklist was presented according to the user and seismic reinforcement method.

• Educational Technology International
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• 제6권2호
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• pp.59-67
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• 2005

The primary purposes of this study are to develop a Situated Learning Support System based on an MMORPG (Massively Multiplayer Online Role Playing Game) and to investigate applications of Situated Learning theory both hypothetically and practically. In Situated Leaning theory, cognition is interpreted as a dynamic system related to situation, context and activity. According to this theory, learning context, social interaction and personal direct experience are also emphasized. A virtual reality learning system based on an MMORPG provides context, social interaction and a learning environment able to provide direct experiences. However, such a system has been difficult for teachers to develop. This study aims to develop a support system facilitating the construction of a Situated Learning System based on an MMORPG. This study proposes new research and practical applications of Situated Learning theory using educational games.

• 한국유기농업학회지
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• 제9권3호
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• pp.1-22
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• 2001

This article described the production problems, import conditions of organic livestock products and background of CODEX-guideline, and presented the counterplan for future organic livestock production policy. The essential counterplan for CODEX-guideline and construction of organic livestock production basis include ; - Specific funding of research and development for excellent livestock breeding with consideration of regional enviroment-friendly applications to improve the quality of organic livestock products, - Development of production potential and resources utilization of organic feeding stuffs in domestic and foreign countries, - Horizontal and vertical organization of organic livestock farming and multifarm cooperation, - Specialization of organic livestock farming, and construction for direct or indirect linkage markets and Agro-food corporation for closer cooperation between inner and outer factor of farm management, - Construction of recycling system for the enviroment-friendly utilization of animal excrements.

• International Journal of Quality Innovation
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• 제7권1호
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• pp.48-59
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• 2006

The Swedish construction sector has been criticized in media for being corrupted, unproductive and conservative. Several incidents, e.g. cartels, work on the side without paying tax and moisture problems, have had a great deal of attention. Of that reason has the government initiated a number of investigations in order to identify the major problems in the construction industry. Further, they have initiated a development of a tool aimed for (a) to identify risks, (b) to avoid poor quality costs, and (c) to direct towards increased quality and effectiveness in building and civil engineering projects, from a client perspective. The UK Constructing Excellence has often been held up as a model during the debate. However, the Swedish general culture differs from the British, as well as the Swedish system differs from the British. The purpose of this paper is to describe the program for developing the system, including the purposes with the system, identified starting points and demands and the approach/method for the development.

• 드라이브 ㆍ 컨트롤
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• 제10권4호
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• pp.34-40
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• 2013

The transmission control method of small forklift is classified into pilot control method and direct control method. In pilot control method, the hydraulic circuit which consists a lot of components is very complex so the production process is too costly and time consuming. The direct control method contains fewer components that can be configured to simple hydraulic circuit. It has more advantages because the shift sensitivity of transmission is changed easily via the input profile. In this paper, the controller design and the input profile for system are studied to apply to the direct control method. The input profile consists of Fill section, Hold section and Ramp section. The characteristic of each section is obtained through experiment. As the result, the shift sensitivity and starting performance are effected by Fill section and Hold section.

• 한국건축시공학회지
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• 제6권2호
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• pp.111-117
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• 2006

In case of carrying out vortical crossing water distribution system in expressways or general roads construction, VR(Vibrated and Rolled reinforced concrete) pipes are restricted because of their specification of reinforced spun concrete pipe or on-site made pipe. Therefore, in order to apply VR pipes to those constructions, through the structural behavior experiments of the pipes, VR pipes are compared and verified with reinforced spun concrete pipe and the results are obtained as the following. From the experiments and analyses of Pipe Stiffness(PS) of the pipes, cracking loading is approved to satisfy the KS regulations. Through a direct load test, the cracking loading strength and the maximum load test of VR pipe is larger compared with reinforced spun concrete pipe. Particularly, even if side weld is thin, there is no little change in the cracking strength of VR pipe. The results of the direct load test analysis show that the structural behavior of VR pipe is equivalent or higher compared with reinforced spun concrete pipe in performance and VR pipe could be used as the water distribution pipe for roads. In this study, through pipe stiffness, direct load test and load teat on earth, reinforced spun concrete pipe and VR pipe are compared. And as a result, the structural behavior of VR pipe is comprehensively excellent. From the structural behavior tests, VR pipe's section shows more thickness and has uniform characteristics so that VR pipe is considered more favorable than reinforced spun concrete pipe.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.8-14
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• 2014

The transmission control method of a small forklift is classified into a pilot control method and a direct control method. In the pilot control method, the complex hydraulic circuit consists of many components, making the production process too costly and time consuming. The direct control method contains fewer components that can be configured to simple hydraulic circuits. As another advantage, the input profile easily changes the shift sensitivity of the transmission. Therefore, this research considers the characteristics of the direct control method in the development of hydraulic system design. This paper will present a simulation of the direct control transmission using AMESim. First, modeling of the direct control method is obtained and simulated with real parameters. The simulation results then are carried out and compared with the experimental results to verify and analyze the characteristics of the direct control method.