• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1039-1042
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• 2002

SMD(Surface Mounting Device) which mounts electronic components as IC-Chips on PCB automatically, produces a large dynamic force and vibration. The unwanted vibrations in SMD degrade the performance of the precision device and it is the major obstacle to limit its speed for mounting. This study investigated the vibration analysis of a typical SMD to predict the natural frequencies and mode shapes. To validate the finite element analysis of SMD, the FE result was compared with that of ODS measurements. It was shown that the predicted results were well correlated with the experimental modal parameters.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.237-240
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• 2001

There are several electricity applied sterilizers such as sterilizer with high frequency, sterilizer with ozone, sterilizer with high voltage, and so on. Those sterilizers feature “because there is no chemical process, there is no secondly environmental pollution” At the power conversion part, AVS and ZCS methods have been used that it results in reduced switching loss, miniaturized size, and lightened weight. Besides, the current in the device is smaller than that of existing method. Thus, it is expected that the cost of sterilization process, when quality of the device is measured by power consumption, will be reduced.

• Annual Conference of KIPS
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• 2004.05a
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• pp.1355-1358
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• 2004

This paper describes a modification to the SACK (Selective Acknowledgement) Transmission Control Protocol's (TCP), called SACK TCP with Probing Device, SACK works in conjunction with Probing Device, for improving SACK TCP performance when more than half a window of data lost that is typical in handoff as well as unreliable media. It shows that by slightly modifying the congestion control mechanism of the SACK TCP, it can be made to better performance to multiple packets lost from one window of data.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.412-417
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• 2004

In urban rail transit systems, ground faults in the DC traction power supply system are currently detected by the potential relay, 64P. Though it detects the fault it cannot identify the faulted region and therefore the faulted region could not be isolated properly. Therefore it could cause a power loss of the trains running on the healthy regions and the safety of the passengers in the trains could be affected adversely. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. A current limiting device, called Device X, is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. One type of the relaying schemes is called directional and differential ground fault protective relay which uses the current differential scheme in detecting the fault and uses the permissive signal from neighboring substation to identify the faulted region correctly. The other is called ground over current protective relay. It is similar to the ordinary over current relay but it measures the ground current at the device X not at the power feeding line, and it compares the current variation value to the ground current in Device X to identify the correct faulted line. Though both type of the relays have pros and cons and can identify the faulted region correctly, the ground over current protective relaying scheme has more advantages than the other.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.109-115
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• 2020

In this paper, the problem that occurs when negative voltage is generated using an inexpensive buck device in an IT device that is supplied with a single power by an adapter or battery is analyzed. For the cause analysis, the principle of operation of the buck device and the principle of the inverter circuit were examined, and the circuit characteristics of the inverter circuit were analyzed using the buck device. As a result of the analysis, it was confirmed that the inverter circuit using the buck device initially needs a large starting current, and in particular, in the case of a current capacity that is less than the starting current in the circuit that supplies power, it was confirmed that it could fall into a state similar to the latch-up phenomenon. In order to confirm the analysis result, an experimental circuit was constructed and the input current was checked. If the supply current is sufficient, it is confirmed that over-current flows and starts. If the supply current is insufficient, the circuit cannot start and a latch-up phenomenon occurs.

• Journal of Korea Multimedia Society
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• v.15 no.11
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• pp.1384-1390
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• 2012

It is well known that the exercising and stimulating of fingers have an important bearing on the brain. We take note of the fact and develope a game device for improving one's health and brain ability in respect of the education and training. Especially, we develope the device focused on the balanced exercising of five finger for improving brain function. The game device is possible to used in two-ways, namely online and off-line mode. In online mode, the device is connected with other visual devices such as smart phone and smart TV and communicated with Bluetooth and it is used as a MMI(multi-modal interface) device. Whereas, in off-line mode the game device works independently and it makes possible to enjoy auditorial and tactual games without video images for promotion of brain activity and emotional cultivation. For certification of the device, we implement two games(a fishing game for off-line mode and a shooting game for online mode) for people of all age, especially good for the elderly. It is usable as a game device to offering the elderly a great help for preventing impairment of the cognitive functions.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.88-91
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• 2002

The two dimensional size effect of specimen gauge section (length x width) was investigated on the compressive behavior of a T300/924 [45/-45/0/90]3s, carbon fiber-epoxy laminate. A modified ICSTM compression test fixture was used together with an anti-buckling device to test 3mm thick specimens with a 30$\times$30, 50$\times$50, 70$\times$70, and 90mm$\times$90mm gauge length by width section. In all cases failure was sudden and occurred mainly within the gauge length. Post failure examination suggests that $0^{\circ}$ fiber microbuckling is the critical damage mechanism that causes final failure. This is the matrix dominated failure mode and its triggering depends very much on initial fiber waviness. It is suggested that manufacturing process and quality may play a significant role in determining the compressive strength. When the anti-buckling device was used on specimens, it was showed that the compressive strength with the device was slightly greater than that without the device due to surface friction between the specimen and the device by pretoque in bolts of the device. In the analysis result on influence of the anti-buckling device using the finite element method, it was found that the compressive strength with the anti-buckling device by loaded bolts was about 7% higher than actual compressive strength. Additionally, compressive tests on specimen with an open hole were performed. The local stress concentration arising from the hole dominates the strength of the laminate rather than the stresses in the bulk of the material. It is observed that the remote failure stress decreases with increasing hole size and specimen width but is generally well above the value one might predict from the elastic stress concentration factor. This suggests that the material is not ideally brittle and some stress relief occurs around the hole. X-ray radiography reveals that damage in the form of fiber microbuckling and delamination initiates at the edge of the hole at approximately 80% of the failure load and extends stably under increasing load before becoming unstable at a critical length of 2-3mm (depends on specimen geometry). This damage growth and failure are analysed by a linear cohesive zone model. Using the independently measured laminate parameters of unnotched compressive strength and in-plane fracture toughness the model predicts successfully the notched strength as a function of hole size and width.

• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.121-127
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• 2017

Recently, many patients in a hospital are threatened life by fire disaster. Because many patients like vulnerable people have more evacuation problem than ordinary person. So a patient who can escape by oneself with walking assistance device like crutches or wheelchair and another patient who can't escape by oneself are should be supported safety technologies and service. Earlier research of 'hospital evacuation' led by actual experiments or computer evacuation simulation. Actual experiment is effective to gain credibility of result but it is difficult for patients to experiment repeatedly and it requires consideration for spatial problem and economic problems. Although computer evacuation simulation have been used to solve these problems, almost have concluded only results based on velocity without evacuation device. In this study, evacuation results with support device application or not are analysed used by computer evacuation simulation based on MAS(Multi Agent System). As a result, it is drawn through proof of efficiency of evacuation device in the vertical space like stairs that can improve the evacuation plan for vulnerable people in the hospital.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.3 s.11
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• pp.24-28
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• 2006

This paper proposed design and implementation of automation system that recognize device module boards automatically that are connected on main control board. The system of this paper is divided to main board and device module boards, and the main board is designed a board by slot structure. The slot structure is possible a extension for upgrade and addition of board ability. Besides, it is easier a establishment and disjointing because it recognizes automatically a device board. The proposed system in this paper compares with K10S1 PLC. The result shows an advantage of extensibility and ability, and it is reduced expense and period for development.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1715-1718
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• 2005

During demonstrations of a process conditioning spent nuclear fuels, it may be necessary to transport and handle Spent fuel road cuts from Post Irradiation Examination facility to Slitting device in The hot cell. It may be not easy to transport spent fuel rod cuts because rod cuts are high radioactive materials. For this purpose, we have developed a capsule for transporting and handling high radioactive materials. We have analyzed conditions of a hot cell and requirements of the device, designed and manufactured The prototype of the device, and done some performance tests. From the tests, it has been shown that transportation and handling without scattering nuclear material was smooth but the weight of capsule was heavy. These result will be reflected to a design of the improved transportation and handling device which will be used during demonstrations.