• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.113-117
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• 1995

Grinding operations is accomplished by rotating a gfinding wheel with lots of random abrasive at high speed, and its object is generally obtained the fanal workpiece surface of high quality as well as the maximization of workpiece removal rate. But, especiallysince grinding operations is related with a large amount of functional parameter, it is actually difficult to therapy that the grinding trouble occurs during the grinding process. Therefore, we trytodesign grinding trouble-shooting system utilizing the back-propagation model of neural network. The conceptual method is produced byidentifying the four parameters derived from the grinding power, and we are design te to the grinding trouble-shooting system on the basis of their data. In this paper, cognition and therapy method tothe grinding trouble which utilizes neural network based four identified models are suggested, and implementation results of computer simulation with respect to the grinding burn and chatter vibration is presented.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.661-666
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• 2000

Near-wake flow field of a circular cylinder is studied by means of a cinematic PIV system with high sampling rate and large internal memory block. Experiments are conducted in a closed-cycle water tunnel system and a cross-correlation algorithm in conjunction with FFT (Fast Fourier Transform) analysis and an offset correlation technique is used for vector processing. With the help of very high sampling frequency compared to the shedding frequency, it is possible to obtain phase-averaged information of the three-dimensional wake, even though the shedding is not forced but natural. Phase-locked vortical structures observed simultaneously from the spanwise and cross-stream planes are displayed in the wake-transition regime where fine-scale secondary vortices have a spanwise wavelength or around one diameter. Spatial relations and temporal evolutions of the primary Karman vortex and the secondary vortex are also discussed schematically.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.153-154
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• 2007

In this paper, we propose context information communication system using RF module to prevent railway cross accident. Since the communication module transmits to the train with high bit rate, OFDM(Orthogonal frequency division multiplexing) modulation method that distributes high speed data and transmits multiple times is applied. And image information is transmitted to the train's transceiver device by using ISM band (2.4GHz frequency band) that is proper to mobile communication. By using this system, we can deal with urgent situations at the railway cross and prevent railway cross accidents in advance.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.149-158
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• 1999

The modern trends of optical storage devices can be characterized by high density in information recording, and high bandwidth in data input/output processing rate. These make servo engineers to face with a new barrier on control system design in much more difficult way. The first step to attack this barrier will be through a systematic modeling for the dynamic characteristics of optical storage drive. in this paper, an analytical dynamic model for an optical storage drive based on FEM is drived, and compared with experimental results. Through this comparison, a practical dynamic model on the focusing and tracking motion of optical storage drive is proposed for the initiation of real control system design problem.

• ETRI Journal
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• v.33 no.1
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• pp.136-139
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• 2011

A modular upgrade design for packet transport switch nodes is presented where packet loss is dramatically reduced by intra-module and inter-module buffer sharing. This modular design offers significant cost and power reduction in a high-data-rate system where buffers are highly costly and power-greedy.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.668-670
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• 2011

본 논문에서는 고속 무선 데이터 전송을 위하여 멀티버스 구조 및 유연적인 데이터 버퍼시스템을 갖는 향상된 바이너리 CDMA에 시스템 설계에 관한 것이다. 개선된 바이너리 CDMA 시스템 구조는 제한된 리소스에서 시스템 버스의 Latency를 최대한 줄이고 고속 무선 데이터 전송을 위하여 버퍼접근구조를 변경하여 데이터 throughput을 향상하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.339-342
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• 1999

The equation of output voltage from the PVDF was derived. When impact force applied to the PVDF films of cantilever beam and one-end fixed, other-end supported beam structure, output voltage equation induced. Experimental output voltages by falling ball agreed quite well with induced theoretical data. This PVDF film showers to be in high possibility in a warning system of abnormal pulse rate and breathing, and in detecting impact force and/or mechanical energy.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.3
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• pp.298-307
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• 2023

Objectives: The purpose of this study is to analyze the recent trends in patients with work-related musculoskeletal disorders in South Korea and to check the major results by reviewing the literature on the risk factors and prevalence of musculoskeletal diseases related to work. Methods: Industrial disaster data from the Ministry of Employment and Labor from 2012 to 2021 were used, and the literature was reviewed regarding risk factors for musculoskeletal diseases related to work using PubMed and RISS. Results: The trend of patients with work-related musculoskeletal disorders has increased overall since 2017 after declining until 2016, with a particularly notable increase in the average annual number of patients with physical burden work. The average annual rate per ten thousand people for patients with body burden work, non-accidental lower back pain, and carpal tunnel syndrome among work-related diseases was high in the mining industry. The average annual rate per ten thousand people for patients with accidental lower back pain was the highest in the fishing industry. Within the manufacturing field, it was the highest in the shipbuilding and ship repair industry. As a result of the literature review, the search rate for work-related musculoskeletal disease papers in unstructured work was high. In addition, physical stress factors were high among risk factors, and pain areas showed a high rate for the waist. Conclusion: Even after the institutional implementation of a hazard investigation system related to musculoskeletal diseases is implemented, the number of patients with occupational musculoskeletal disorders continues to increase. Therefore, it is necessary to conduct regular surveys and implement effective improvement activities for vulnerable industries or occupations.

• Journal of Biosystems Engineering
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• v.42 no.2
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• pp.75-79
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• 2017

The use of tractors to carry out agricultural work has played an important role in mechanizing the agricultural sector. A repairable mechanical system (such as an agricultural tractor) is subject to deterioration or failure. In this study, a regression model was used to predict the failure rate of a John Deere 3140 tractor. The machine failure pattern was carefully studied, and key factors affecting the failure rate were identified in five regions of the Khouzestan province. Through a questionnaire, data was obtained from farm records. This data was grouped into six sub-groups, according to the annual use hours (AUH) and the manner in which the tractors were stored. Results showed that AUH and storage policies affected failure rate slightly. With an increase in the age of the tractors, the failure rate in the tractors used for 1050-2000 hours annually and stored outdoors was higher than those used for 200-1000 hours annually and stored in sheds. When the tractors were of the same age, the slope of the curve in the 200-1000 annual use hours increased gradually and then rapidly, but failure rate in the 1050-2000 annual use hours was high from the beginning, and subsequent increase in this value was almost uniform. As a result, it can be said that with an increase in the annual use hours, the failure and breakdown rate in John Deere 3140 tractors rapidly increases, but maintenance conditions only slightly affect the failure and breakdown rate.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.446-449
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• 2003

In recent years, the research of an efficient transmission method is going to meet a demand for high speed and large capacity radio communication. These systems make use of ultra-short duration pulses which yield UWB(Ultra Wide Band) signals characterized by low power spectral densities. The wavelet synthesis wave is able to set up the scale freely. So it is possible to use as the transmission wave of UWB by compressing time. In this paper, we present a general analytical expression for the average BER(Bit Error Rate) performance of UWB data transmission using wavelet system as a function of the cross-correlation between the users' signatures in an additive white Gaussian noise(AWGN) channel.