• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.867-874
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• 2023

Recently, many problems are occurring in the bee ecosystem due to rapid climate change. The decline in the bee population and changes in the flowering period are having a huge impact on the harvest of bee-keepers. Since it is impossible to continuously observe the beehives in the hive with the naked eye, most people rely on knowledge based on experience about the state of the hive.Therefore, interest is focused on smart beekeeping incorporating IoT technology. In particular, with regard to swarming, which is one of the most important parts of beekeeping, we know empirically that the swarming time can be determined by the sound of the queen bee, but there is no way to systematically analyze this with data.You may think that it can be done by simply recording the sound of the queen bee and analyzing it, but it does not solve various problems such as various noise issues around the hive and the inability to continuously record.In this study, we developed a system that records queen bee sounds in a real-time cloud system and analyzes sound patterns.After receiving real-time analog sound from the hive through multiple channels and converting it to digital, a sound pattern that was continuously output in the queen bee sound frequency band was discovered. By accessing the cloud system, you can monitor sounds around the hive, temperature/humidity inside the hive, weight, and internal movement data.The system developed in this study made it possible to analyze the sound patterns of the queen bee and learn about the situation inside the hive. Through this, it will be possible to predict the swarming period of bees or provide information to control the swarming period.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2094-2105
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• 1994

This paper contains a Hough transform based projection method derived from Radon transform for tracking dim unresolved(sub-pixel) moving targets that move along straight line parths across a time sequential image data. In contrast to several recently presented Hough transform methods using a compressed image referred to as the track map our proposed technique utilizing a set of projections taken along arbitrary orientations effectively increases the changes of target detection, and creates a robust track estimation environment by incorporating all the available knowledge obtained from the projections. Moreover, in order to quantitatively assess the estimation capability of the projection-based Hough transform algorithm, the analytical bounds on the Hough space parameter errors introduced by image space noise contamination are derived. The simulation yielded promising results of estimating the track parameters even under low signal to noise rations when our technique was tested against the time sequential sets of real infrared image data referred to as the HiCamps.

• Explosives and Blasting
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• v.30 no.2
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• pp.21-28
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• 2012

Blasting methods are frequently used in case of forming slope artificially like slope cutting and open-cut method in the downtown area because of many economical and effective advantages. It is important that blasting work is carried out maintaining original strength of rock and not to damage rock face. And it is also considered that blasting method to decrease ground vibration is essential to the point of blast damages due to the ground vibration. In this study, to form a smooth plane of rock slope face, many trial blasts were carried out in this way that explosives were installed in detonating cord by equal interval in different charging method and stemming method. Using 4 blasting patterns in total 60 blast holes and 20 times of blasts were carried out. At the same time ground vibration measurements were carried out 15~102m away from the blast source, and total number of 310 data were obtained. Measured data for ground vibration velocity were analyzed so as to study blasting method to protect slope plane while decreasing blast vibration in an effective way.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.454-459
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• 2013

Pressure waves are generated and propagate in a tunnel when train enters tunnel high speed. A compression wave due to the entry of train head propagates along the tunnel and is reflected at tunnel exit as an expansion wave. An expansion wave due to the entry of the train tail propagates along the tunnel and is reflected at tunnel exit as a compression wave. These pressure waves are repeatedly propagated and reflected at the tunnel entrance and exit. Severe pressure changes causes ear-discomfort for passengers in the cabin and micro pressure waves around the tunnel exit. It is necessary to analyze the transient pressure phenomena in tunnels qualitatively and quantitatively, because pressure change rate is considered as one of the major design parameters for optimal tunnel cross sectional area and repeated fatigue force on car body. In this study, we developed a characteristics method based on a fixed mesh system and boundary conditions for crossing trains and analyzed this system using an X-t diagram. The results of the simulation show that offsetting of pressure waves occurs for special entry conditions of a crossing train.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.436-441
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• 2012

Pressure waves are generated and propagate in tunnel when train enters a tunnel with high speed. Compression wave due to the entry of train head propagates along the tunnel and is reflected at tunnel exit as expansion wave. While expansion wave due to the entry of train tail propagates along the tunnel and is reflected at tunnel exit as compression wave. These pressure waves are repeatedly propagated and reflected at tunnel entrance and exit. Severe pressure change per second causes ear-discomfort for passengers in cabin and micro pressure wave around tunnel exit. It is necessary to analyze the transient pressure phenomena in tunnel qualitatively and quantitatively, because pressure change rate is considered as one of major design parameters for an optimal tunnel cross sectional area and the repeated fatigue force on car body. In this study, we developed the characteristics method analysis based on fixed mesh system and compared with the results of real train test. The results of simulation agreed with that of experiment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.2
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• pp.197-217
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• 2020

Shield TBM tunneling, used in the construction of Seoul subway line 7 and line 9, has been well known as a very efficient, as well as safe, tunneling method. Although the Shield TBM method has been known to be effectively used in poor ground conditions, a number of troubles have occurred during the use of the shield TBM, due to inappropriate machine selection, machine breakdown, and unpredicted ground conditions etc. In this study, several accidents and trouble cases occurred during excavation by Shield TBM, reported from Japan, were investigated. A series of numerical analysis was then performed to compare with the trouble cases and back-analysis results for the cause analysis. The lessons learned from the case studies are presented at the end.

• Journal of the Korean Magnetics Society
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• v.21 no.5
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• pp.167-173
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• 2011

Underwater static magnetic field signature for the naval ship has been widely used as the detonating source of the influence mine system because it is possible to make an accurate target detection in the near field although the magnetic field falls off relatively fast with distance in comparison with the underwater radiated noise signal. In this paper, we describe the prediction results about the underwater static magnetic field by the ferromagnetic hull, the internal structures and the main on-board equipment for the target vessel using the commercial FEM software. Also we analyze the degaussing effectiveness for the target vessel through the degaussing coils arrangement.

• The Journal of Society for e-Business Studies
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• v.23 no.2
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• pp.111-121
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• 2018

Many problems in rotating machinery such as aircraft engines, wind turbines and motors are caused by bearing defects. The abnormalities of the bearing can be detected by analyzing signal data such as vibration or noise, proper pre-processing through a few signal processing techniques is required to analyze their frequencies. In this paper, we introduce the condition monitoring method for diagnosing the failure of the rotating machines by analyzing the vibration signal of the bearing. From the collected signal data, the normal states are trained, and then normal or abnormal state data are classified based on the trained normal state. For preprocessing, a Hamming window is applied to eliminate leakage generated in this process, and the cepstrum analysis is performed to obtain the original signal of the signal data, called the formant. From the vibration data of the IMS bearing dataset, we have extracted 6 statistic indicators using the cepstral coefficients and showed that the application of the Mahalanobis distance classifier can monitor the bearing status and detect the failure in advance.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.196.2-196.2
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• 2011

지구온난화와 화석연료 고갈에 대한 우려로 전세계적으로 신재생에너지의 개발 및 활용이 본격화되고 있다. 특히, 다양한 신재생에너지원 중에서 날씨 및 계절에 의한 영향, 기저부하 담당, 지상 점유 면적, 소음 등 생활환경 영향, 경제성 등을 고려할 때 지열에너지는 미래 청정에너지원로서 기대와 관심이 집중되고 있다. 화산이 존재하지 않는 우리나라에서의 지열발전은 거의 불가능한 것으로 인식되어 지금까지의 심부 지열에너지 개발 프로젝트는 대부분 지역난방, 시설영농 등 직접이용을 목표로 추진되어 왔다. 그러나, 2003년부터 한국지질자원연구원에서 수행한 포항 심부지열에너지 개발사업의 결과로 얻어진 다양한 지질학적/지열학적 증거들을 토대로 분석한 결과, 국내 일부 지역에서는 지하 5 km 심도에서 최대 약 $180^{\circ}C$의 지온이 예상되어 국내에서도 심부 지열에너지를 이용한 지열발전에 대한 가능성이 제기되어 왔다. 여기에, 유럽과 미국 그리고 호주 등 선진국을 중심으로 비화산 지역에서 지하 심부에 인공적으로 지열저류층(파쇄대)을 생성하고 이를 통해 열매체(물)를 순환시킴으로써 생산된 증기를 발전에 활용하는 EGS (Enhanced Geothermal System) 기술이 개발되고 몇몇 성공사례가 발표되었다. 또한, 이러한 기술개발에 힘입어 EGS 지열발전에 대한 선진국의 과감한 연구비 투자가 이어졌다. 이러한 기술적 배경에 발맞추어 우리나라에서도 2010년 12월에 EGS 지열발전 과제가 착수되었다. 이 프로젝트는 아시아에서는 최초로 수행되는 EGS 기술 개발과제로서 2015년까지 약 480억원의 R&D 예산을 투입하여 MW급의 지열발전 pilot plant의 구축을 목표로 하고 있다. 프로젝트가 성공적으로 추진될 경우 국내외적인 파급효과는 매우 클것이다. 특히 2015년까지 1.5 MW의 pilot plant의 구축이 성공적으로 추진될 경우 국내에서는 2017년까지 3 MW 이상, 2020년까지 20 MW이상, 2030년까지 200 MW 이상의 지열발전이 가능할 것으로 기대된다. 또한 축적된 기술개발 경험을 바탕으로 인도네시아, 필리핀 등의 해외의 지열발전 사업에도 진출할 수 있는 계기가 될 것이다. 프로젝트는 넥스지오를 주관기관으로 하고 한국지질자원연구원, 한국건설기술연구원 및 서울대학교 등의 지질자원 관련 연구 및 교육기관과 포스코, 이노지오테크놀로지 등의 산업체가 참여하여 컨소시엄 형태로 추진하고 있으며, 향후 관심있는 여러 기관 및 산업체의 지원과 참여를 기대한다.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.352-364
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• 1997

This study examined and analyzed users' behavior to recreation forest facilities and their satisfaction to recreation forest in order to offer some basal data which would be helpful to create new recreation forest, to supply users' needs in exsiting recreation forest, and to make excellent maintenance of recreation forest. The results are as follows ; Restroom, campground and forest aromatic bath ground were the most popular facilities with the users of recreation forest. And restroom, snack stand and water cooler were the most required facilities by the users. Before using recreation forest, users' expectation to enjoy aesthetics of nature, to be released from their fatigue and to rest, was the highest one. And users were satisfied most as they expected most from recreation forest. The major variables played for users' satisfaction about facility allocation and its harmony to the forest, were how clean the facilities are, how well they are repaired and maintained, how much noise users make around them, how easy to use them, and how beautiful the surroundings are. Users' satisfaction variables about vegetation condition of recreation forest, were diversity of vegetation, the shade of trees, the reservation of the forest, and the accordance of vegetation with the surroundings. Users' satisfaction variables about facility condition in recreation forest, were how easy to access to the recreation facilities and restroom, how clean they are, how well the trash cans are allocated, how easy to access to the field kitchen. And how good the forest is protected and nurtured, how well the forest managers conduct users' behavior, how effectively recreation forest is guided and informed to the public, were their major satisfaction variables about the management of Recreation Forest.