• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1477-1485
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• 1996

Since the spindle bearing systme is the main source of the total cutting point compliance of machine tool structures, in this work, the static and dynamic characteristics of the spndle bearing systme driven by the gear located on the bearing span were investigated using analytical and finite elemtn methods to improve the performance of the spindle bearing system. Based on the theretical results, a specially designed prototype spindle bvearing systme was manufactured. Using the manufactured spindle bearing system, the static and dynamic characteristics were measured. From the comparison of the experimental results with the theoretical results, it was found that the finite elemetn method predicted well the static and dynamic characteristics of the spindle bearing system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.20-25
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• 2011

In this paper, we reviewed the spindle system's motor and bearing and its mode safety for optimal design of a high speed spindle system that exceeds DmN value of 1,500,000. We could verify that it has a separation margin during critical speed by performing critical speed analysis. Also, we have selected an optimal sensoring installation location and actually manufactured & installed the sensor by identifying the stress concentration position in the axial load through finite element analysis to install the built-in piezo electric type load sensor to the spindle housing that can measure and monitor the machining load during high speed rotation of the spindle. Reproducibility is also verified by calibrating the error through the sensor's sensitivity adjustment after comparing the output between the plate dynamoneters and the load sensor to confirm the reproducibility of the load sensor.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.118-125
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• 1999

In the grinding process, generally, the exciting forces with high frequency can be generated due to the wheel wear and the grinding process. As the grinding speed increases, the precise investigation about the wheel dynamic characteristics is required. Conventionally the wheel-spindle has been considered with lumped model in dynamic modeling. With this lumped model, the significant mode resulted from the shell mode of wheel can be readily ignored. This paper suggests the new analysis model which includes the shell mode of wheel in modeling the wheel-spindle assembly. Furthermore, based on the suggested model, the effects of the bolt tightening force and the taper tightening force on the dynamic properties are investigated by the finite element modal analysis and the experimental method. As a result of investigation, the shell mode vibration of wheel affects the dynamic characteristics of the spindle assembly. Also, the vibration modes of the spindle assembly are significantly affected by the joint tightening forces.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.51-58
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• 2005

Many RC building structures of multiple uses constructed in Korea have the Irregularities of torsion and soft story at bottom stories simultaneously. Seismic design codes generally require dynamic analysis and to take into account the effect or earthquake excitations in the orthogonal direction using the approximate methods of 100/30 and SRSS for type of building structures. And ail buildings should be designed to be safe in any direction of earthquake input. But, most of designers have difficulty in considering the orthogonal and directional effect of earthquake. The objective of the study stated herein is to verily 1) the effect of the choice of the reference axes on the seismic design member forces by comparing the analytical results on member forces using the principal axes suggested by Wilson and the global axes generally adopted in design office, 2) the validity or the 100/30 and SRSS methods by comparing the member forces obtained through linear elastic time history analysis with those obtained through using response spectrum analysis and 100/30 (or SRSS) methods. Based on the observations on the analytical results, it is concluded as follows; 1) The values of member forces by principal axes can be about $15\%$ smaller than those by the global axes in the example structure. 2) Though the values of member forces given by time history analysis are generally within the peak values predicted by 100/30 and SRSS methods, many member force vectors $(P,\;M_y,\;and\;M_z)$ by lime history analysis were located outside the boundaries predicted by the approximate method such as the 100/30 method.

• Convergence Security Journal
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• v.5 no.4
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• pp.7-18
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• 2005

Recently, ISO/IEC SC27 WG3 is actively working on the revision of CC V3.0 to be an international standard by 2008, principally supported by Common Criteria Development Board (CCDB). Hence, it is essential for Korea to review and analyze the changes in CC V3.0, so as to be completely prepared for any change to be occurred from CC V2.* to V3.0. Taking into account of CC V3.0 being revised currently, this paper gives a general overview of revision in CC V3.0 : then, closely examines and explains the improvements and changes made by the revision in CC V3.0

• Bulletin of Korea Environmental Preservation Association
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• s.379
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• pp.14-29
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• 2009

최근 세계 경제는 사상 유래를 찾기 힘든 경제위기에 홍역을 앓고 있다. 국제유가를 비롯한 원자재가격은 수급불균형과 정치적 이슈, 그리고 투기자본의 유입이 어우러져 급등락을 거듭하고 있다. 또한, 지구온난화를 막기 위해 국제사회에서 추진하고 있는 기후변화협약도 큰 어려움을 겪고 있다. 선진국들은 배출권 거래제도 시행, 탄소세 도입 등을 통해 본격적인 환경 무역시대가 도래에 대비하고 있으며, 포스트 교토체제에 대한 협상도 본격화 되고 있어 대응이 시급한 실정이다. 자원 환경위기의 시대에 녹색성장은 불가피한 선택이 되었으며 우리나라에서도 온실가스 감축을 위해 많은 노력을 하고 있다. 정부에서는 탄소포인트제도 도입과 10대 녹색기술 산업 육성, 그린 뉴딜을 통한 녹색일자리 4만 3천개 창출 등 기후변화 대응을 위한 정책들을 추진하고 있으며, 또한 저탄소 녹색성장의 한 주축으로 신재생 에너지 기술개발 및 보급의 확대를 통해 세계시장 선점을 위해 매진하고 있다. 환경부에서는 폐기물에너지화, 기후변화대응, 환경산업육성 등 '저탄소 녹색성장'을 이끌 사업과 '경제 살리기'에 역점을 두고 2009년도에는 환경부 소관예산 '08년 예산 3조 5,914억원 대비 5,008억원(13.9%) 증액된 총 4조 922억원을 투자할 계획이다. 이에 본지에서는 지난호에 이어 저탄소 녹색성장을 위한 녹색자원 기술 육성II로 주제를 잡고 "온 국민이 참여하는 기후변화 대응 정책 추진", "녹색성장 정책 추진에 있어 기업체 지원방향", "우리나라 신재생에너지 기술개발현황과 앞으로의 과제", "가정에서 온실 가스 줄인만큼 혜택받는 탄소은행"등에 대하여 살펴보고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.5 s.248
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• pp.560-567
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• 2006

The exact load measurements for the mechanical parts of a wind turbine are important step both fur the evaluation of a specific wind turbine design and for a certification process. A common method for a mechanical load measurement is using a strain gauge sensing. Two main problems ought to be answered in order for this method to be applied to the wind turbine project. These are strain gauge calibration and non-contact signal transmission from the strain gauge output to a load monitoring system. This paper suggests reliable solutions fer these two problems. A Bluetooth, a short range wireless data communication technology, is used to solve the second problem. The first one, the strain gauge calibration methodology for a load measurement in a wind turbine application, is fully explained in this paper. Various mechanical loadings for a strain gauge calibration in a wind turbine load measurement are introduced and analyzed. Initial experimental results which are obtained from a 1 kW small size wind turbine are analyzed, and the uncertainty problem in estimating mechanical loads using a calibration matrix is fully covered in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.564-565
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• 2019

The Internet of Things technology is regarded as the next major technology that will be the driving force behind the fourth industrial revolution. The characteristics of entities for Internet of Things application are changing more actively and actively, requiring a more detailed approach, but existing access control technologies are designed around users, requiring access control techniques that maintain efficiency and security with less system load to apply complex and variable content. Therefore, research on role-based access controls that are appropriate for Internet of Things entities is essential. In this study, the relevant research for the study of access control of the Internet of Things entities and the RBAC and AC methods that can define the properties of the various entities within the Internet of Things.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.57-63
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• 2022

This study describes a system that monitors the tool and cutting state of automatic beveling operation in real time. As a signal for cutting state monitoring, a motor current detected from the spindle drive system of the automatic beveling machine is used to monitor abnormal state. Because automatic beveling is processed using a face milling cutter, the cutting force mechanism is the same as the milling process. The predicted cutting torque is obtained using a cutting force model based on specific cutting resistance. Then, the predicted cutting torque is converted into the spindle motor current value, and cutting state stability is diagnosed by comparing it with the motor current value detected during beveling operation. The experimental results show that the spindle motor current can detect abnormal cutting state such as overload and tool wear during beveling operation, and can diagnose the cutting stability using the proposed equip-current line diagram.

• KOREAN POULTRY JOURNAL
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• v.40 no.1 s.459
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• pp.112-116
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• 2008

국제 곡물가격이 연일 급등세를 보이며 세계 곡물시장이 요동치고 있다. 10년 전인 1996년 엘리뇨 현상에 따른 지구촌의 기상이변으로 곡물파동을 겪은 바 있다. 10년 이상 지난 지금까지 일부 최빈국을 제외한 대다수의 국가가 곡물파동의 아픔을 잊고 행복한 시간을 보내지 않았나 하는 생각이 든다. 세계 경제가 미국을 중심으로 민주주의와 자본주의 경제가 주축을 이루며 경제적인 부, 즉 돈만 있으면 언제든지 쌀독에 쌀을 가득 채울 수 있었기 때문에 먹거리의 중요성에 대하여 소홀하며 살아온 것 같다. 그러나, 이제 더 이상 돈만 있다고 원하는 만큼 먹거리를 확보하기란 쉽지 않는 시대가 도래하고 있다. 작년 하반기부터 국제곡물가격은 가히 폭등이라고 할 만큼 큰 폭으로 상승하였는데, 문제는 과거처럼 단순히 기상악화에 따른 작황부진과는 차원이 다르다는 것이다. 지구촌 기상이변에 더불어 세계 경제성장에 따른 소비구조 변화와 이에 따른 수급불균형이 더욱 심화되고 있다는 것이다. 이에 금년도 세계 곡물산업 현황과 가격변동 흐름을 짚어보고 향후 사료원료를 중심으로 곡물수급 전망을 조명하고자 한다.