• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.120-126
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• 2018

The traffic accident types are largely classified into vehicle to vehicle accident, vehicle-to-person accident and single-vehicle. Especially, the single-vehicle accident types are severe when the vehicle crashed into road facilities such as bridge, piers, utility poles. The severity of single-vehicle accidents are ten times higher than that of all other accidents types. It is needed to consider to reduce accident severity. This study was conducted to develop crash worthy safety design facility to ensure the vehicle occupant safety. The simulation and the crash tests were conducted for assessment of the safety performance to check the criteria of CC2(Crash Cushion 2) level. THIV(Theoretical Head Impact Velocity) and PHD(Post-impact Head Deceleration) were used to assess occupant impact severity for crashes. The non-redirection collision test conditions for 900 kg and 1,300 kg-head on crash tests, 900 kg-1/4 offset crash tests, 1,300 kg-head on crash test with $15^{\circ}$angle were conducted. The simulation and experiment test result showed that THIV values were below 44 km/h criterion, PHD values were below the 20G. The development non-redirective crash cushion is expected to be used for the fixed object such as bridge piers for assuring occupant safety.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.781-783
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• 2014

Mobile ad hoc network(MANET) consists of node that has mobility. MANET has increased overhead that caused by frequent topology changes. For reducing overhead, hierarchical network that communicates through cluster head node has been researched. When traffic is concentrated on cluster head node, cluster member node can't send message. To solve this problem, we proposed Step Parent algorithm. Proposed algorithm, cluster member node checks traffic of cluster head node using route path of other cluster head node in efficient coverage area. When cluster head node has increased traffic, cluster member node make a new route path by route path by routing path to another cluster head node. So cluster member node sends a message to destination node, we check improving delivery ratio.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.506-507
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• 1992

When it comes to the 'Leak Detector System' generally, our country has a large income 'Rotary Type Leak Detector' of foreign goods. The completed development of the 'Line Type Leak-Detector' system was produced to check Whether the containers for small and large on the filling line are auto defective. This system is applied to the filling package Processing during the production and contributed to inproving competiveness of domestic containers manufactures of all society of Industry. Also, high precision and realiablity, very compact size, low cost and Easy set-up etc. by checking the experimental data directly plan, Design and making for '1 Compression Head Control Leak Detector System'. This flexcible system can be equipped with multiple Compression heads depending on the requested prodution test rate and test precision.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.20-25
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• 2012

A Crankshaft multi grinding machine is developed for manufacturing of high precision crankshaft. The grinding head part of the developed machine should be moved precisely during grinding of work materials. In this paper, structural and modal analysis for the crankshaft multi grinding machine is carried out to check the design criteria of the machine. The analysis is carried out by FEM simulation using the commercial software. The machine is modeled by placing proper shell and solid finite elements. The results of structural and modal analysis confirmed that the structural characteristics of grinding machine and the structural safety are considered secure.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1147-1151
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• 2013

A Crankshaft Multi Grinding Machine is developed for manufacturing of high precision crankshaft. The grinding head part of the developed machine should be moved precisely during grinding of work materials. In this paper, structural and modal analysis for the crankshaft multi grinding machine is carried out to check the design criteria of the machine.

• The Mathematical Education
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• v.45 no.4 s.115
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• pp.481-491
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• 2006

Diffy is a simple mathematical puzzle that provides elementary-school students with subtraction practice. The idea appears to have originated in the late nineteenth century with E. Ducci of Itali. Thirty years ago Professor J. Copley of the University of Houston introduced the diffy game to teachers in elementary schools and it widely spreaded out. During the diffy activity we naturally guess many interesting conjectures. First, does diffy always end? Second, does the head of diffy always exist? Third, for an arbitrary given natural number n, is there any possible method to find the diffy with the given length n? In this study I give the necessary and sufficient condition for the existence of the head of diffy. Using this condition I classify all possible heads of diffy and provide an algorithm to find the diffy with any given length n. With this algorithm I find four natural numbers with diffy length 200. To ensure my numbers are correct, I make a diffy program for Mathematica and check they are correct. I suggest the diffy game is good for enlarging the mathematical thinking to all graded students, especially gifted and talented students, It will produce rational consideration and synthetic judgement.

• Korean Journal of Head & Neck Oncology
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• v.7 no.1
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• pp.45-51
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• 1991

최근 횡문근육종을 치료함에 있어서 수술적 요법, 방사선 치료, 강암 약물요법을 적절히 병행함으로써 치료에 따르는 후유증을 극소화하면서 괄목할만한 생존율 향상을 가져오게 되었다. 특히 두경부의 횡문근육종은 소아에서 다발하고 병소의 위치에 따라서 각각 다른 임상적 특성을 가지며 수술적 절제를 했을 때 기능 및 외견상 결손이 크므로 별도의 연구 대상이 되어 왔으며 수술적 방법보다는 방사선 치료 및 항암 약물요법이 강조되고 있다. 저자들은 1976년부터 1987년까지 두경부 횡문근육종으로 진단받고 연세 암센터에서 항암 약물요법 및 방사선 치료를 받은 22명의 환자를 대상으로 하여 발생 부위, 조직 병리, 병기별 분포 및 생존율, 치료 방법에 따른 생존율을 후향성으로 분석하였다. 22명의 환자중 10 세 미만이 12 예로 가장 많았고, 13명이 배아세포형이였으며, 임상병기는 병기 III 이 가장 많아서 14 예였다. 병소의 위치는 안와가 6명으로 가장 많았고, 뇌수막주변부가 7명 (상악동 3명, 중이도 2명, 비강 l명, 비인강 1명), 기타 9명 (경부 5명, 이하선 2명, check 2명) 이었다. 5년 무병 생존율은 안와 종양에서 가장 높아서 50% 였고, 안와외 두경부가 37.5%, 뇌수막주변부가 16.7% 로 가장 낮았으며, 낮은 병기(병기 III), 배아세포형, 항암 약물 요법 병용군에서 상대적으로 높은 생존율이 관찰되었다.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.58-60
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• 2007

Magnetic Resonance Imaging(MRI) has become a very widely used medical procedur e. Clo.sed and open systems are typically used with static magnetic fields at or below 2 Tesla. BWhole body SAR(specific absorbsion rate) is the value of SAR averaged over the entire body of the patient over any period of 15 minutes. Head SAR is the value of SAR averaged over the head of the patient for any period of 10 minutes. SAR is a measure of the absorption of electromagnetic energy in the body' (typically in watts per kilogram (W/kg)). The normal operating mode comprises values of head SAR not higher than 3 W/kg. The second level controlled operating mode comprises values higher than 3 W/kg. Current FDA guidance limits the SAR in the whole body. including the head to a range of 1.5 to 4.0 W/kg, depending on the patient's clinical condition. SAR, limit restrictions are incorporated in all MRI systems. and domestic' s guidance limits the SAR in a part body. including the head to 3.2w/kg and less. The purpose of this study is to evaluate on change of head SAR in using MRI pulse sequence and to check if exceed 3.2(w/kg) level in domestic a part exposure through measured head SAR. 23 patient's the average head SAR of pulse sequence is that T2WI sagittal is 0.5375. T2WI axial(FSE) is 0.4817, T1WI axial(SE) is, 0.8179. FLAIR axial is 0.4580. GRE axial is 0.0077, Diffusion is 0.0824w/kg. The head SAR exposed per patient was proved 2.3845w/kg less than the international standard. Coefficient of correlation for the relations body weight and SAR or for the relations ETL(echo train length) and SAR is 1 value. Coefficient of correlation for the relations between TR(time to repeat) and SAR is -0.602 value. so SAR increased relative to weight body and ETL. But the relations between TR and SAR is negative definite.

• Journal of the Ergonomics Society of Korea
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• v.36 no.4
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• pp.267-280
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• 2017

Objective: The aim of this study is to investigate key user experience factors of interactions for Head Mounted Display (HMD) devices in the Virtual Reality Environment (VRE). Background: Virtual reality interaction research has been conducted steadily, while interaction methods and virtual reality devices have improved. Recently, all of the virtual reality devices are head mounted display based ones. Also, HMD-based interaction types include Remote Controller, Head Tracking, and Hand Gesture. However, there is few study on usability evaluation of virtual reality. Especially, the usability of HMD-based virtual reality was not investigated. Therefore, it is necessary to study the usability of HMD-based virtual reality. Method: HMD-based VR devices released recently have only three interaction types, 'Remote Controller', 'Head Tracking', and 'Hand Gesture'. We search 113 types of research to check the user experience factors or evaluation scales by interaction type. Finally, the key user experience factors or relevant evaluation scales are summarized considering the frequency used in the studies. Results: There are various key user experience factors by each interaction type. First, Remote controller's key user experience factors are 'Ease of learning', 'Ease of use', 'Satisfaction', 'Effectiveness', and 'Efficiency'. Also, Head tracking's key user experience factors are 'Sickness', 'Immersion', 'Intuitiveness', 'Stress', 'Fatigue', and 'Ease of learning'. Finally, Hand gesture's key user experience factors are 'Ease of learning', 'Ease of use', 'Feedback', 'Consistent', 'Simple', 'Natural', 'Efficiency', 'Responsiveness', 'Usefulness', 'Intuitiveness', and 'Adaptability'. Conclusion: We identified key user experience factors for each interaction type through literature review. However, we did not consider objective measures because each study adopted different performance factors. Application: The results of this study can be used when evaluating HMD-based interactions in virtual reality in terms of usability.

• Korean Journal of Head & Neck Oncology
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• v.37 no.2
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• pp.19-24
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• 2021

Background/Objectives: The aim of this national population-based retrospective study was to analyze the status and treatment outcome in patients with hypopharyngeal cancer. Materials & Methods: Participants were included in the KNHIS national sample cohort who received a KNHIS health check-up in 2008 and 2009, and we followed these individuals until 2017. Patients were defined as having hypopharynx cancer if they had admissions records for hypopharynx cancer in their national health insurance data from 2010 to 2017. Results: The study cohort included 3,922 patients. According to our nationwide data, 3,533(90.1%) were male with a median age of 65.03±11.04 years at the time of diagnosis. Among parametric models for hypopharyngeal cancer prognosis, old age (Hazard ratio [HR]:1.92; 95% confidence interval[CI]:1.76-2.09), female (HR:0.77; 95% CI:0.66-0.89), and low socioeconomic status (HR:1.216; 95% CI:1.114-1.327) were significantly associated with survival. Compared with concurrent chemoradiotherapy, patients who received no treatment (HR, 1.88; 95% CI, 1.31-2.70), neoadjuvant chemotherapy followed by surgery (HR, 1.21; 95% CI, 1.04-1.41), and chemotherapy alone (HR, 1.16; 95% CI, 1.03-1.27) showed poor prognosis in hypopharyngeal cancer. Conclusion: Our data indicated that age, sex, and income were significant predictors of lifetime survival in patients with hypopharyngeal cancer. Treatment modalities were also associated with prognosis. The data have implications for treatment investigations and prevention strategies.