• Journal of the Ergonomics Society of Korea
• /
• v.32 no.6
• /
• pp.489-494
• /
• 2013

Objective: This study compared the effects of streamlined shoes on dynamic gait and foot plantar pressure in healthy young adults. Background: With the importance of ankle and lower extremity mechanism, streamlined shoes are contributing to a static gait factors. However, the study of dynamic gait factor is still insufficient. Method: Sixty subjects were randomly allocated to two groups: experimental group(n=30) and control(n=30), respectively. The experimental group performed streamlined shoes, whereas the control group applied usual shoes. Main outcome measurements were assessed contact time, step length and foot plantar pressure using gait analysis with the treadmill. Independent t-test was used to compare the both groups. Results: Compared with control group, contact time of forefoot, midfoot and hindfoot decreased significantly in experimental group(p<.05), Step length increased significantly in experimental group(p<.05). Foot plantar pressure of midfoot and hindfoot increased significantly in experimental group(p<.05), whereas that of forefoot did not show significantly in experimental group(p>.05). Conclusion: Our findings suggest that streamlined shoes was more effective than usual shoes in dynamic gait change including contact time and step length and foot plantar pressure in healthy young adults. Application: The results of streamlined shoes might help to control for the gait of industrial workers.

• Journal of Communications and Networks
• /
• v.18 no.3
• /
• pp.502-512
• /
• 2016

The wireless carrier sense multiple access with collision detection (WCSMA/CD) and carrier sense multiple access with collision resolution (CSMA/CR) protocols are considered representative distributed collision detection protocols for fully connected dense wireless local area networks. These protocols identify collisions through additional short-sensing within a collision detection (CD) period after the start of data transmission. In this study, we analyze their throughput numerically and show that the throughput has a trade-off that accords with the length of the CD period. Consequently, we obtain the optimal length of the CD period that maximizes the throughput as a closed-form solution. Analysis and simulation results show that the throughput of distributed collision detection protocols is considerably improved when the optimal CD period is allocated according to the number of stations and the length of the transmitted packet.

• Proceedings of the Korean Society for Bio-Environment Control Conference
• /
• 2001.04b
• /
• pp.41-42
• /
• 2001

The objectives of this study were to investigate the effect of the physical properties of wick on the water absorption of substrate. Physical properties of wick in this study were cotton composition, width and length. The water Infiltration rate through the wick was 0.24 ㎝/s at 90 -95% cotton content, which was faster than at 80-85% (0.13 cm/s) and 70-75% (0.08 cm/s). As the cotton content increased, the water absorption of substrate became greater : the amount of absorbed water was about 5-7g higher at 90-95% than at 80-85% and 70-75% at a wick width of 1 ㎝, the velocity of water absorption through the wick was fastest with 0.25 ㎝ㆍs/sup -1/. The amount of absorbed water was higher at 3 ㎝ than at 1 and 2 ㎝. However, the water absorption rate through the cross - sectional area of wick (g H₂O /㎠/hr) was higher at a wick width of 2 ㎝ than at those of 1 and 3 ㎝. The amount of absorbed water in the substrate was higher at 2 : 1 than at 1 : 1 (length in substrate : length out of substrate). Absorbed water amount was larger at 30-40% initial moisture content than any other treatment.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.16 no.2
• /
• pp.36-48
• /
• 1991

In this study, an efficient algorithm is developed to compute steady state probabilities for the following M$_{x}$G/1 server vacation system under control-operating poligy: At the end of a busy period, the server takes a sequence of vacations, each for a random amount of time. At the end of each vacation, he inspects the length of the queue. If the queue length at this time is equal to or greater than a prespecified threshold value r, he begins to serve the queue until it is empty.y.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.1076-1079
• /
• 1993

A fuzzy digital controller is combined an autopilot system for compensating the cross coupling effect of the induced roll due to the dynamic characteristic of three fin torpedo. However the utilization of fuzzy chip has many interfacing problems with typical microprocessors of the guidance and control unit. Since a fuzzy digital controller on a microprocessor uses a finite word length A/D converters arul D/A converters, ADC and DAC may generate nonlinear effects such as deadband and limit cycle phenomena. In this paper, the robustness of fuzzy digital controller is tested with ADC a finite word length.

• Journal of Korean Institute of Industrial Engineers
• /
• v.28 no.3
• /
• pp.319-330
• /
• 2002

We consider BMAP/G/1 queueing system with N-policy and multiple vacations. We derive the vector generating functions of the queue length in a factorized form and interpret the factorization. We also derive the mean queue length.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1211-1215
• /
• 2005

In the GPS attitude determination system, the baseline length constraints can be used efficiently to reduce the search space. It is possible by adopting the assumptions that the baseline length doesn't change and the true baseline length is precisely known. But in real situation, the baseline length might be changed by many reasons and it is impossible to measure the true baseline length because there exists measurement error and antenna phase centre movement. In order to analyze the effect of the baseline length accuracy, one needs to know the relation between the accuracy of the baseline length and success rates of the integer ambiguity resolution. In this paper, the effect of the baseline length accuracy to the integer ambiguity resolution in the attitude determination system is analyzed by empirical method. The results show that the margins in the baseline length accuracy is less than a few cm which implies that one should take great cares when applying the attitude determination system to the flexible structures.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.3
• /
• pp.481-490
• /
• 2002

The purpose of this paper is to evaluate the efficiency of various solution techniques and propose new efficient solution techniques for space trusses. Solution techniques used in this study are three load control methods (Newton-Raphson Method, modified Newton-Raphson Method, Secant-Newton Method), two load-displacement control methods(Arc-length Method, Work Increment Control Method) and three combined load-displacement control methods(Combined Arc-length Method I , Combined Arc-length MethodⅡ, Combined Work Increment Control Method). To evaluate the efficiency of these solution techniques, we must examine accuracy of their solutions, convergences and computing times of numerical examples. The combined load-displacement control methods are the most efficient in the geometric nonlinear solution techniques and in tracing post-buckling behavior of space truss. The combined work increment control method is the most efficient in tracing the buckling load of spate trusses with high degrees of freedom.

• Communications for Statistical Applications and Methods
• /
• v.23 no.6
• /
• pp.497-515
• /
• 2016

Modern processes often monitor more than one quality characteristic that are referred to as multivariate statistical process control (MSPC) procedures. The MSPC is the most rapidly developing sector of statistical process control and increases interest in the simultaneous inspection of several related quality characteristics. Most multivariate detection procedures based on a multi-normality assumptions are independent, but there are many processes that assume non-normality and correlation. Many multivariate control charts have a lack of related joint distribution. Copulas are tool to construct multivariate modelling and formalizing the dependence structure between random variables and applied in several fields. From copula literature review, there are a few copula to apply in MSPC that have multivariate control charts, and represent a successful tool to identify an out-of-control process. This paper presents various types of copulas modelling for the multivariate control chart. The performance measures of the control chart are the average run length (ARL) and the average number of observations to signal (ANOS). Furthermore, a Monte Carlo simulation is shown when the observations were from an exponential distribution.

• Journal of the Korean Society of Costume
• /
• v.52 no.8
• /
• pp.29-39
• /
• 2002

It was increased leisure hours by automation and computerization of industry. Many people spend on hours in enjoying leisure sports, and then. nowadays, Many women tend to prefer casual wear to formal suits. The purpose of this research was to design of outdoor-wear that improve the functional and aesthetic effects for clothing comfort. Total 4 design prototype consisting of jumper and slacks were developed for this research. Outdoor-wear design forced on armhole type of jumper and ease of the back crotch length of slacks to improve the functional and aesthetic effects. And Outdoor-wear design focused on color harmony to aesthetic effects. Ease amount and materials of jumper and slacks were controlled. Design A: Jumper was designed as dropped shoulder with set-in steeve and band collar, A break-away zipper to facilitate ventilation control were made the area of back of jumper and the area of outside seam line of slacks Color of jumper and slacks were olive green color. Ease amount of the crotch length of slacks pattern was constructed as 7% of total crotch length: Design B 4DM cut pattern were applied to the jumper and slacks pattern. A break-away zipper to facilitate ventilation control were made the area of back of jumper and the area of inside seam line of thigh. Color of jumper and slacks were grey and orange color. Ease amount of the crotch length of slacks pattern was constructed as 5% of total crotch length. Design C : Jumper was designed as the set in sleeve and hood. and A break- away zipper to facilitate ventilation control were made the ares of the armhole and elbow. Color of jumper and slacks were ivory and orange color. Ease amount of the crotch length of slacks pattern was constructed as 5% of total crotch length. Design D : Jumper was designed as raglan sleeve. Color of jumper and slacks were olive green color. Ease amount of the crotch length of slacks pattern was constructed as 5% of total crotch length. Total six females, ages 20-45, served as subjects for this research. Subjects have standard body type, generally, wearing 66 size of ready-to-wear clothing. The performance of the newly designed outdoor-wear was evaluated for their effectiveness in several aspects such as conditions of skin temperature, sensory evaluation of comfort during body movements, appearance and color harmony and aesthetic collar design. Design 3 was appeared to be the most positive in aesthetic evaluation and functional effects of design 2 of 4DM cut pattern was appeared to be beter than other designs.