• Journal of the Korean housing association
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• v.27 no.5
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• pp.55-63
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• 2016

This study intended to establish a direction for the revitalization of youth culture centers by examining the current status of youth centers operated in Daejeon and how they have been used. Four youth centers in Daejeon were visited and a survey was conducted targeting 180 people using the centers. Frequency, Mean, and ${\chi}^2$ analysis were performed by using SPSS statistics package, and major research outcomes are as follows; There were 6 youth culture centers in Daejeon and showed a lower construction rate of 7.4% on the basis of 81 up, myun and dong. Most youth centers were small, around $300-500m^2$ in total floor area, and accommodated 100-200 people, and the space comprised multipurpose hall, cafeteria, open space, club space, multimedia space, information service room, and guide booth. There were no sports spaces among the target facilities. So, it has created the need for physical activity space to promote health & development. Most users visited centers with their friends and simply to use the facilities, and the satisfaction with the facilities was relatively high at 4.32. The role of the local community and financial support of the government is required to activate the youth culture. Also, for the role of youth culture center, it was suggested that the youth culture center should develop program which corresponds with the level of the youth and boast the interest of the youth.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.47-54
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• 2009

Spin coaters are the essential instruments in micro-fabrication processes, which apply uniform thin films to flat substrates. In this research, a spin coater diagnosis system is developed to detect the abnormal operation of TFT-LCD process in real time. To facilitate the real-time data acquisition and analysis, the circular-buffered continuous data transfer and the short-time Fourier transform are applied to the fault diagnosis system. To determine whether the system condition is normal or not, a steady-state detection algorithm and a frequency spectrum comparison algorithm using confidence interval are newly devised. Since abnormal condition of a spin coater is rarely encountered, algorithm is tested on a CD-ROM drive and the developed program is verified by a function generator. Actual threshold values for the fault detection are tuned in a spin coater in process.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.39-40
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• 2016

Power conversion system comes with a twenty-year warranty commonly. Life test requires a long time. The life of power conversion system that especially sensitive to temperature can be expected within a short time by using Arrhenius technique with worst stress condition than actual working condition. This paper researches reliability analysis and environment test of power conversion system.

• Journal of Power System Engineering
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• v.21 no.6
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• pp.94-100
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• 2017

Due to the environmental problems caused by the greenhouse effect, regulation of $CO_2$ emissions is getting stronger day by day. In paricular, regulations of automobiles $CO_2$ emissions are being strengthen. However, existing $CO_2$ measurement methods do not reflect the environment and operating conditions on actual roads. Emissions of $CO_2$ can be increased by various conditions such as environmental condition(temperature and humidity) and driver's tendency(aggressive and passive). Therefore it is necessary to reflect the conditions of various actual roads such as 5-cycle test method on behalf of the existing $CO_2$ emission measurement method. The 5-cycle measurement method has five test modes; FTP-75, HWFET, US06, SC03, Cold FTP-75. The method reflects the following three environments and operating conditions as compared to conventional method; Using heater at low temperature, Aggressive driving such as rapid acceleration or deceleration, Using air conditioner at high temperature. Because of these various conditions of each test cycle, the 5-cycle method can reflect actual environments and operating conditions. This paper attempt to analyze $CO_2$ emission characteristics based on the results measured through the 5-cycle mode and develop the correction formula that can derive the results of the 5-cycle test method using existing test methods. As a result, the developed correction formula is expected to reduce $CO_2$ emissions and cut down expense for testing 5-cycle mode.

• Journal of Korean Society for Quality Management
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• v.46 no.2
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• pp.269-282
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• 2018

Purpose: The purpose of this study was to improve the FRP Van's durability by analyzing the problematic parameters, redesigning the rear van, and verifying the design drafts using the CAE analysis & Rig test. Methods: The collected data through the government quality inspection and field spot check were thoroughly analyzed through the characteristics diagram and the improvement suggestions were verified by performing CAE analysis, like the dynamic stiffness, Torsional stiffness, open/close condition's strength, Full car durability and Carrying out the actual test. Results: The results of this study are as follows; The output of CAE analysis shows that improvement suggestions have considerable effects on the reinforcement of FRP structure, and the actual torsion and open/close condition durability test prove that rear van may have durable life which is equivalent to vehicle life cycle. Conclusion: The structural weakness of KLTV's FRP rear van was overcome by applying the stiffener in rear van and changing the bonding method of each FRP pieces. That suggestions were proved using CAE analysis and Rig test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.484-487
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• 2005

In order to get the surface characteristics of the HDI of HDD, the surface damage mechanisms must be totally understood. Particle contamination in hard disk drives is a big concern in today's magnetic recording industry since they are major sources of reliability problems. Namely upon contact with the slider or a contaminant particle, the disk may be scratched or the particles may be embedded into the disk surface. In this work, comparison of scratches was made between those found on actual hard disks and those created using a scratch tester. It was found that ramp loading method is an effective way to make similar scratches as the actual ones. From the ramp loading condition, the relationship between the pressure and the scratch track width could be identified.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.69-80
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• 1993

It is important to prevent roll failure in hot rolling process for reducing maintenance coat and production loss. Roll material and rolling conditions such as the roll force and torque have been intensively investigated to overcome the roll failures. In this study, a computer roll life prediction system under working condition is developed and evaluated on IBM-PC level. The system is composed and fatigue estimation models which are stress analysis, crack propagation, wear and fatigue estimation. Roll damage can be predicted by calculating the stress anplification, crack depth propagation and fatigue level in the roll using this computer model. The developed system is applied to a work roll in actual hot rolling process for reliability evaluation. Roll failures can be diagnosed and the propriety of current working condition can be determined through roll life prediction simulation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.2
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• pp.103-111
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• 2000

The objectives of the study are to know the strain distribution and modal dynamic behaviour of steel bridge girders by actual traffic load. The live load effect depends on many parameters including the span length, gross vehicle weight, axle weight, axle configuration so on. For the estimation of static and dynamic characteristic, strain data caused by moving loads and traffic characteristics of passing vehicle under actual traffic load have measured using Bridge Weigh in Motion. To confirm the reliability of BWIM system, strain data measured using the $120{\Omega}$ strain gauge under the same condition. It is considered that the data acquired from BWIM system have reliability through the analysis and comparison between stress measured by strain data from BWIM and computed by FEM. Additionally according to the measured strain data of up-line and down-line on the highway, the up-line bridge grows more faster than the down-line bridge and girder 4 and 5 carry more load when vehicles pass the inner line and girder 2 and 3 does when vehicles pass the outer line as this case(the bridge composed with 5 girders).

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.146-153
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• 2000

The rubber crawler system for farm machine is composed of driving units such as track rollers, driving sprockets and rubber crawlers. Vibration characteristics of the rubber crawler system varies by driving speed, center of gravity, mass□moment of inertial□location arrangement of track rollers and dynamic parameters such as dynamic spring constant (k) and viscous damping coefficient (c) of a rubber crawler. In general, vibration of the rubber crawler system occurs by reason for mechanical interaction between the rubber crawler and track rollers. Because the dynamic spring constant and viscous damping coefficient vary periodically by mechanical characteristics(deformation characteristics) of the rubber crawler when track rollers drive on the between lugs of the rubber crawler. Therefore, both dynamic parameters k and c were expressed as Fourier series by authors through the shaking test of the rubber crawler and further, vibration characteristics of the rubber crawler system could be simulated analytically. However, actual values of dynamic parameters k and c are different from those obtained by the shaking test because dynamic characteristics of the rubber crawler vary by the effect of variable tension and driving resistance of track rollers. So, actual values of k and c should be identified in the condition of actual driving test. In this study, dynamic parameters such as k and c of the rubber crawler system, which are expressed as Fourier series, were identified using the Gauss-Newton Method. Therefore, validity of identified parameters k and c was discussed through the simulation using experimental data of actual driving test. As a result, in the Fourier series of dynamic parameters of spring constant k and viscous damping coefficient c, excellent parameter convergence and simulation were observed using the Fourier series' zero order and first term of the dynamic model. Furthermore, it was clarified that identification for model parameters which are fitted to actual dynamic motion (vibration) wave of the crawler system was possible by using the time series data observed in vertical and pitching motion of the crawler system.

• Journal of Korean society of Dental Hygiene
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• v.4 no.1
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• pp.1-17
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• 2004

The purpose of this study is to investigate the actual condition of consciousness that the students in Dept. of dental hygiene who will be engaged in dental hygiene at a dental office in the future have about a clinical training, to see whether there is any difference between the results, and then to provide fundamental data which can be helpful to develop more effective clinical training programs. For this, we investigated consciousness, that 114 daytime school students and evening school students(76 daytime school students and 38 evening school students) in Dept. of dental hygiene in J college have, using questionnaires on clinical training with Self-Administrated Method. SPSS 12.0 for Windows was used to analyze all of the questionnaires, and the results analyzed at meaningful level a=.05 are like followings: 1. The degree of satisfaction on clinical training was high as average 3.30 ; it was high in case of night training as 3.34, and of a dental office in a general hospital and an university hospital as 3.83. The degree of stress caused by clinical training was high as average 3.30, and it means that they are under relatively heavy pressure ; it was shown they got the most heavy stress as 3.39 at night, as 3.68 at a dental clinic 2. The students showed the highest tendency to recognize that clinical training is needed "for learning various clinical case experiences" as average 3.54 ; the students trained at daytime showed the highest average 3.55, and at a clinical hospital, the highest average 3.64. 3. In the study on an actual condition of consciousness about clinical training according to class difference by time(at day time and at night), there is meaningful difference between two kinds of class ; the students trained at day time showed average 2.68 that they don't like to attend, on the other hand the students at night showed higher average 2.84(p<.05). In the study on an actual condition of consciousness about clinical training according to the institutions they are trained, there is meaningful difference at satisfaction on learning method and amount of assignment : they show the highest degree of satisfaction on the learning method in case of working at a dental office in a general hospital and an university hospital as average 3.3(p<.0.1) ; the amount of assignment was shown most high at a dental clinic and a dental office in a general hospital and an university hospital as average 3.00 each(p<.05). 4. In the study of the degree of satisfaction on the clinical training, it has relatively high connections with learning contents(r=.656), learning methods(r=.497), special lessons and supplementary lessons(r=.472), the case they don't like attend at work (r=-.439), discriminatory treatment(r=-.25l), respectability on the senior dental hygienists(r=.464), a social status of a dental hygienist(r=.213), the degree of satisfaction from the relationship with other dental hygienists(r=.274), the degree of understanding which clinical training institutions have on the trained students(r=.494), trainers' ability to teach the students(r=.499). enthusiasm on guiding (r=.523), the amount of assignment(r=.333). 5. In the study on stress they got from a clinical training, it has relatively high connections with learning contents(r=-.399). learning methods(r=-.536), comprehension on training program(r=-.208), special lessons and supplementary lessons(r=-.306), the case they don't like attend at work(r=.467), discriminatory treatment(r=.366), respectability on the senior dental hygienists(r=-.341), a social status of a dental hygienist(r=-.l97), the degree of satisfaction from the relationship with another dental hygienists(r=-.289), the degree of understanding which clinical training institutions have on the trained students(r=-.430), trainers' ability to teach the students(r=-.396), enthusiasm on guiding(r=-.495).