• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.418-424
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• 2017

Magnesium has a higher specific strength than other metals and is widely used industry wide due to its excellent vibration absorption ability and electromagnetic wave shielding property.For example, it is used for automobile parts such as car seat frames and cylinder heads, and is widely used in electronic products such as notebook cases and mobile phone cases. In addition, it is in the spotlight as a bone-implant material used to assist in the treatment of damaged bones when the bones are cracked or broken. Currently, Ti alloy, stainless steel and Co-Cr-Mo alloy are used as the implant material, and the Mg alloy remains in research stage. The current problem with bone implant implants is that the patients must undergo reoperation to remove the implants after joint surgery. Magnesium, however, can achieve sufficient strength compared to current materials. In addition, since it is self-decomposed after the recovery, reoperation is not necessary. In this paper, Mg alloys were designed by adding harmless Ca and Zn to the human body. In order to improve the strength and corrosion resistance, the final alloy was designed by adding a small amount of Sr as a grain refiner. The radioactive elements of Sr are harmful to the human body, but other naturally occurring Sr elements are harmless. Microstructure analysis of the alloys was performed by optical microscopy and scanning electron microscopy. The mechanical properties and corrosion characteristics were evaluated by tensile test, potentiodynamic test and immersion test.

• 전자공학회논문지 IE
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• v.44 no.2
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• pp.8-13
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• 2007

This paper aims to analyze the characteristics of ITO which are caused by variation of plasma condition to fabricate the OLED of high efficiency. We treated $N_2$ gas and $O_2$ gas plasma on the surface of the ITO by changing their RF plasma power into 100 W, 200 W, 400 W and by changing their 9as pressure into 12 mTorr, 120 mTorr. The work function of ITO that plasma treatment was done by using $N_2$ gas had value of $4.88{\sim}5.07\;eV$, and that by using $O_2$ gas, $4.85{\sim}4.97 eV$. The characteristics of the ITO were most efficient in the $N_2$ gas plasma with the RF power of 200W and gas pressure of 120 mTorr. The rms roughness of ITO surface is the value from AFM image. In this case, ITO obtained $25.2\;{\AA}$ and $30.5\;{\AA}$ in the $N_2$ and $O_2$ gas plasma respectively when it had the RF power of 200 W. But ITO that didn't have plasma treatment was $44.5{\AA}$. The variation of ITO transmittance was almost not discovered by the change of $N_2$ gas and $O_2$ gas pressure.

• Archives of design research
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• v.13 no.4
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• pp.57-66
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• 2000

The Korea's automotive industry have been achieved a remarkable growth with various original models since the first original model ‘Pony’for the 25years. Most of the design works were depended upon the designers of the other countries on the early times, but now the design work gets to have the independency with our own technology and the automobile is now one of the major exporting goods of Korea to other countries. The basic design concept of the body shape can be considered into four types, and they have their own characteristics. The period of time for the original model developement of the Korean auto makers can be thought as four periods ; introducing period, settling period, developing period and matured period are them. The models that developed on each period reflects the characteristics of the times with designers, technology and market conditions. The basic design concepts of the Korean car body show the variety but the concepts have been intergrated into the two types as the time gose by. This tendency would comes form mainly technology, but the consumers characteristics of the market would also influence as much as the technological reason. It would become more important on developing the original model with the autonomy in design concept of the body through grasping the change of formal characteristics clearly on an automobile in the future.

• Journal of Internet Computing and Services
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• v.18 no.3
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• pp.29-36
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• 2017

In these days, 3D dynamic simulation is closely related to many industries. In the past, physically-based 3D simulation was used mainly in the car crash or construction related fields, but it also plays an important role in movies or games today. Many mathematical computations are needed to represent the 3D object realistically, but it is difficult to process a large amount of calculations for simulation of application based on CPU in real-time. Recently, with the advanced graphic hardware and improved architecture, GPU can be utilized for the general purposes of computation function as well as graphic computation. Many approaches using GPU have been applied for various research fields. In this paper, we analyze the performance variation of two cloth simulation algorithms based on GPU according to the change of execution properties of GPU shaders in oder to optimize the performance of GPU-based cloth simulation. Cloth simulation is implemented by the spring centric algorithm and node centric algorithm with GPU parallel computing using compute shader of GLSL 4.3. We compare the performance of between these algorithms according to the change of the size and dimension of work group. The experiment is repeated to 10 times during 5,000 frames for each test and experimental results are provided by averaging of FPS. The experimental result shows that the node centric algorithm is executed in higher speed than the spring centric algorithm.

• Journal of Preventive Medicine and Public Health
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• v.37 no.2
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• pp.182-189
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• 2004

Objectives : The objective of this study is to compare the circadian patterns of heart rate variability assessed by 24-hour ambulatory electrocardiographic (ECG) recordings during day shift and night shift among the workers in the 5 days-concecutive-12-hour shift in an automobile factory in Korea. Methods : The study population consisted 300 workers, who were randomly selected among the 8700 total workers in one car factory. To analyse circadian variation, the 24-hour ECG recordings (Marquette) were measured during day shift (08:00-20:00 h) and night shift (20:00-08:00 h). Analysis was performed for all time and frequency domain measures of HRV. 233 workers completed taking 24-hour ECG recordings. Results : This study shows that the 24 hourcircadian variation mainly follows work/sleep cycle rather than day/night cycle among shift workers. This study also shows that among the night shift, the circadian variation between work and sleep cycle decreased compared to the work/sleep cycle among day shift workers. All time and frequency domain parameters (except LF/HF ratio) show significantly different between work and sleep in the day shift and night shift. Conclusion : These changes in heart rate variability circadian rhythms reflect significant reductions in cardiac parasympathetic activity with the most marked reduction in normal vagal activity among the shift workers. Especially, it suggests the circadian rhytm has blunted among the night workers. The quantification of the circadian variation in HRV can be a surrogates of workers' potential health risk, as well as suggests possible mechanisms through which the shift works compromise workers' health.

• Journal of Korean Society of Transportation
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• v.24 no.3 s.89
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• pp.63-71
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• 2006

There were many theories to suggest the indicators that evaluate stability and reflect the plan in mixed traffic street in all traffic modes This Paper analyzed residential street of Suwon City adopting time-space occupancy index among these indicates. Three survey street. congregated into apartment house. were selected to analyze this and pictured by video camera over one hour. and the length of these street were 76m, 55m, and 34m each, and major street by each region, comparably high in Pedestrians and pass vehicles, were selected. Basic datum to calculate time-space occupancy index and time-space occupancy index per person was gathered through video analysis. i.e Parameters for pedestrians, cars, bicycles, average speed of bicycles, and parking car. There are some limitation to analyze LOS of mixed traffic street in all traffic modes, not pedestrian mall. Therefore this paper presented evaluation standard of LOS. In conclusion. the aim of this paper is to suggest modeling based on guidelines for evaluating LOS of mixed traffic street in all traffic modes. It is estimated that this will be influencing indicates for improving pedestrian environment, and Planning mixed traffic street in future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.617-623
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• 2020

Urban railroad vehicles carry many passengers and are the core of an urban railroad transportation system. Therefore, the dynamic performance of the vehicle must be ensured. Dynamic behaviors such as the vibration and ride comfort of railway vehicles are affected by the structure of the suspension system. We analyzed the dynamic behavior of a railway vehicle according to the suspension system of an urban railway vehicle, which is mainly operated in Korea. For two types of vehicles with different suspension structures, the vibration of the vehicles on railway tracks was measured, and dynamic behavior characteristics such as vibration, ride, and vibration reduction rate were analyzed. The result of the test shows that the vibration performance of the body is superior to that of B-bogie in the lateral direction and that of A-bogie in the vertical direction. Overall, the ride quality of the A-bogie car is superior to that of B-bogie. When analyzing the vibration attenuation rate of primary suspension system, the vibration attenuation performance of B-bogie with coil spring was superior to that of A-bogie with a conical rubber spring. The secondary suspension system has better vibration attenuation performance for A-bogie with air springs compared to coil springs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.85-91
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• 2001

Background : It goes without saying that cumulative trauma disorders is spreading to various types of occupation in many advanced countries including America, and it forms considerable rate of total occupational disorders already. and as the result of it, the seriousness of worker health problem and economic loss owing to production loss, recuperation expense, etc. are on the increasing trend through whole society. In case of Korea, the related measures as well as accurate fact-finding survey data on cumulative trauma disorders aren't prepared in detail, so it implies forward problem would be serious. Purpose : The purpose of this study is to draw the risk factor of cumulative trauma disorders in production factory, to forecast the rate of occurrence of cumulative trauma disorders on the basis of subjective symptoms, and to present forward realistic and effective prevention measures by showing the risk of cumulative trauma disorders, objecting the production factory of a domestic riding automobile assembly shop, by estimating in the aspect of human-engineering through the analysis of risk factor being a cause of cumulative trauma disorders. Methods : For this study, I investigated work type and on-duty hours, breathing time, and subjective symptoms of cumulative trauma disorders through questionnaire, objecting the workers in press. car body, coating, and outfit factory. Results : As a result of research, 81.2% of workers were in the physical burden due to present working, and the highest prevalence by part of body is an waist. The higher a rule score, The higher the number of workers complaind for working intensity, and the higher age work duration, tool used time, the higher prevalence of subjective symptoms by part of body. The number of workers complaind subjective symptom for treatment is the highest in drugstore.

• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.207-221
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• 2016

In Korea, older pedestrian accounted for 57% of all pedestrian deaths although a ratio of older pedestrian accidents to total pedestrian accidents was only 25.9%. Though ageing population problem becomes more challenging for road safety, little is know about the behaviour of older pedestrian's behaviour. This study aimed to identify road crossing behaviour of older pedestrian at three-lane unsignalized crosswalks using video image analysis and to compare the behaviour of older pedestrian to younger one by indicators including approaching speed, the number of walking steps and other factors. The results showed that there was a difference of approaching time at kerb, waiting time at kerb, the number of glances at kerb, and the number of glances at crossing between two groups under the situation of car approaching to crosswalks. It also showed that older pedestrian usually spent 1.16 times more than younger pedestrian to walk across the crosswalk with only 84.4% of walking speed of younger pedestrian. The number of steps of older pedestrian for road crossing was 1.12 times higher with 90% shorter steps than younger pedestrian. It was concluded that older pedestrian usually decided to walk across in case of 1.67 times longer headway than younger pedestrian's decision. These results could be applied in road and facility design for better safety of older pedestrians.

• Journal of Korean Society of Transportation
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• v.32 no.3
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• pp.187-197
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• 2014

The objective of this study is to analyze the travel behaviors of customers accessing to three different types of shopping facilities - traditional markets(TM), hyper markets(HM), and super supermarkets(SSM) - and also to find out the most desirable location for each type of shopping facilities that encourage sustainable transportation and smart urban growth. It also demonstrates what mode has the highest percentage of modal split and what is the access distance for public transport mode by each shopping facilities (SSM: 84.5% walking and 667m, TM: 20.1% bus and 1.6km, HM : 46.2% private car and 4.2km). Among TM, HM, and SSM, statistically significant differences are found in terms of mode choices and other associated travel behaviors. The research findings are expected to contribute to finding future urban planning and transportation solutions that promote walking and public transit uses for shopping trips and thus help support green transportation and sustainable urban growth.