• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.147-155
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• 2016

Industry 4.0's goal is the 'Smart Factory' that integrates and controls production process, procurement, distribution and service based on the fundamental technology such as internet of the things, cyber physical system, sensor, etc. Basic requirement for successful promotion of this Industry 4.0 is the large supply of semiconductor. However, company I who produces dicing blades has difficulty to meet the increasing demand and has hard time to increase revenue because its raw material includes high price diamond, and requires very complex and sensitive process for production. Therefore, this study is focused on understanding the problems and presenting optimal plan to increase productivity of dicing blade manufacturing processes. We carried out a study as follows to accomplish the above purposes. First, previous researches were investigated. Second, the bottlenecks in manufacturing processes were identified using simulation tool (Arena 14.3). Third, we calculate investment amount according to added equipments purchase and perform economic analysis according to cost and sales increase. Finally, we derive optimum plan for productivity improvement and analyze its expected effect. To summarize these results as follows : First, daily average blade production volume can be increased two times from 60 ea. to 120 ea. by performing mixing job in the day before. Second, work flow can be smoother due to reduced waiting time if more machines are added to improve setting process. It was found that average waiting time of 23 minutes can be reduced to around 9 minutes from current process. Third, it was found through simulation that the whole processing line can compose smoother production line by performing mixing process in advance, and add setting and sintering machines. In the course of this study, it was found that adding more machines to reduce waiting time is not the best alternative.

• Archives of Reconstructive Microsurgery
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• v.24 no.1
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• pp.1-6
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• 2015

Purpose: The main cause of flap loss in microsurgical tissue transfer is venous insufficiency. Whether or not multiple venous anastomoses prevents vascular thrombosis and reduces the risk of flap failure remains controversial. Some researchers are in favor of performing dual venous anastomoses, but the counterargument holds that performing a single venous anastomosis does provide advantages. Materials and Methods: We carried out a retrospective analysis of 15 cases of anterolateral thigh free flap for extremity reconstruction performed between January 2011 and December 2013. The patients were categorized into two groups: group A that received a single venous anastomosis and group B that received dual venous anastomoses. The time of the anastomosis, size of the flap, complications of the flap, and survival rate of each group were analyzed. Results: The total microsurgical time in the single venous anastomosis group ranged from 28 to 43 minutes (mean 35.9 minutes). The total time in the dual anastomoses group ranged from 50 to 64 minutes (mean 55.7 minutes). No statistically significant difference was found between the two groups with regards to postoperative complications and flap failure. Conclusion: Our study suggests that the use of a single venous anastomosis in the venous drainage of anterolateral thigh free flaps is a safe and feasible option for extremity reconstruction and provides shorter operative time and easy flap dissection.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.224-235
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• 2022

Objective : Since the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, neurointerventionists have been increasingly concerned regarding the prevention of infection and time delay in performing emergency thrombectomy procedures in patients with acute stroke. This study aimed to analyze the effects of changes in mechanical thrombectomy protocol before and after the COVID-19 pandemic on procedure time and patient outcomes and to identify factors that significantly impact procedure time. Methods : The last-normal-to-door, first-abnormal-to-door, door-to-imaging, door-to-puncture, and puncture-to-recanalization times of 88 patients (45 treated with conventional pre-COVID-19 protocol and 43 with COVID-19 protection protocol) were retrospectively analyzed. The recanalization time, success rate of mechanical thrombectomy, and modified Rankin score of patients at discharge were assessed. A multivariate analysis was conducted to identify variables that significantly influenced the time delay in the door-to-puncture time and total procedure time. Results : The door-to-imaging time significantly increased under the COVID-19 protection protocol (p=0.0257) compared to that with the conventional pre-COVID-19 protocol. This increase was even more pronounced in patients who were suspected to be COVID-19-positive than in those who were negative. The door-to-puncture time showed no statistical difference between the conventional and COVID-19 protocol groups (p=0.5042). However, in the multivariate analysis, the last-normal-to-door time and door-to-imaging time were shown to affect the door-to-puncture time (p=0.0068 and 0.0097). The total procedure time was affected by the occlusion site, last-normal-to-door time, door-to-imaging time, and type of anesthesia (p=0.0001, 0.0231, 0.0103, and 0.0207, respectively). Conclusion : The COVID-19 protection protocol significantly impacted the door-to-imaging time. Shortening the door-to-imaging time and performing the procedure under local anesthesia, if possible, may be required to reduce the door-to-puncture and door-to-recanalization times. The effect of various aspects of the protection protocol on emergency thrombectomy should be further studied.

• Journal of Preventive Medicine and Public Health
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• v.30 no.1 s.56
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• pp.171-179
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• 1997

This study was performed to see whether neurobehavioral tests was affected by the exposure-free time in the workers chronically exposed to organic solvents. Thirty-four female workers were participated and four items among neurobehavioral core test battery of World Health Organization, including digit span, Santa Ana Dexterity, digit symbol and Benton Visual Retention, were administered to the workers. Test was conducted three times-preshift on Monday, preshift on Weekday and during shift on Weekday-per person and the interval of tests was 2 weeks. Digit span forward, Santa Ana Dexterity, digit symbol, and Benton Visual Retention showed significant decrements by performing time, especially during shift on Week-day versus preshift on Monday and preshift on Weekday. In addition, the score at preshift on Weekday was significantly lower than preshift on Monday, in preferred Santa Ana Dexterity and digit symbol. Generally, those who were exposed to high concentration, over 50 years and under 6 years of education showed marked decrease of score at during shift. So, it would be desirable that neurobehavioral test is conducted at preshift on Monday and items related to short term memory could be considerable to be done at preshift on Weekday.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1723-1727
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• 2005

A generalized fractional diffusion equation (FDE) is presented, which describes the time-evolution of the spatial distribution of a particle performing continuous time random walk (CTRW) on a fractal lattice. For a case corresponding to the CTRW with waiting time distribution that behaves as $\psi(t) \sim (t) ^{-(\alpha+1)}$, the FDE is solved to give analytic expressions for the Green’s function and the mean squared displacement (MSD). In agreement with the previous work of Blumen et al. [Phys. Rev. Lett. 1984, 53, 1301], the time-dependence of MSD is found to be given as < $r^2(t)$ > ~ $t ^{2\alpha/dw}$, where $d_w$ is the walk dimension of the given fractal. A Monte-Carlo simulation is also performed to evaluate the range of applicability of the proposed FDE.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.283-285
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• 2003

We have developed an optimization algorithm based formulation for performing efficient time driven simultaneous place and route for FPGAS. Field programmable gate array(FPGAS) provide of drastically reducing the turn-around time for digital ICs, with a relatively small degradation in performance. For a variety of application specific Integrated circuit application, where time-to-market is most critical and the performance requirement do not mandate a custom or semicustom approach, FPGAS are an increasingly popular alternative. This has prompted a substantial amount of specialized synthesis and layout research focused on maximizing density, minimizing delay, and minimizing design time.

• Journal of the Korean Society of Safety
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• v.8 no.3
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• pp.44-49
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• 1993

The spontaneous ignition induction time and temperature distribution were observed by performing experiments for granulated activated carbon. As the results of the experiments at the same amplitude, the critical spontaneous ignition temperature was decreased with increase of the time period, while, the ignition induction time was increased with the increase of the time period. The critical spontaneous ignition temperature was decreased with the increase of the amplitude for the shorter period. The temperature distribution of the sample showed the highest around ignition-point at center of the vessel and after ignition the highest temperature was moved toward surface of the vessel.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.343-344
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• 2012

With the increase of sensitive data and their secure transmission and storage, the use of encryption techniques has become widespread. The performance of encoding majorly depends on the computational time, so a system with less computational time suits more appropriate as compared to its contrary part. Double Random Phase Encoding (DRPE) is an algorithm with many sub functions which consumes more time when executed serially; the computation time can be significantly reduced by implementing important functions in a parallel fashion on Graphics Processing Unit (GPU). Computing convolution using Fast Fourier transform in DRPE is the most important part of the algorithm and it is shown in the paper that by performing this portion in GPU reduced the execution time of the process by substantial amount and can be compared with MATALB for performance analysis. NVIDIA graphic card GeForce 310 is used with CUDA C as a programming language.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.224-231
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• 2006

A six-degree-of-freedom dynamic model with time-varying mesh stiffness/damping and friction has been developed for the dynamic analysis of a gear driving system. This model includes a spur gear pair, bearing, friction and prime mover. Using Newton???s method, equations of motion for the gear driving system were derived. Two computer programs are developed to calculate mesh stiffness, transmission error and friction force and analyze the dynamics of the modeled system using a time integration method. The influences of mesh stiffness/damping, bearing, and friction affecting the system were investigated by performing eigenvalue analysis and time response analysis. It is found that the reduction of the maximum peak magnitude by friction is decided according to designing the positions of pitch point and maximum peak in the responses.

• Journal of the Semiconductor & Display Technology
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• v.11 no.3
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• pp.45-50
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• 2012

In this paper, we propose a real-time ECG monitoring system for personal health records. This study aims to provide services that help patients to monitor their own physical condition and manage their own health records consistently, whereas existing medical services are Medical Institute-Centric model. The system is composed of web server, smart phone, and ECG meter, and web page. Without time and space restraints, It provides us with managing personal health records by performing patient's ECG measurement and real-time monitoring. And also Real-time bidirectional communication between smart phone and web page can be performed rapidly by applying the ECG monitoring with WebSocket Technology that follows HTML5 standard. Through this system, It can handle patient in need immediately.