• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1994년도 특별강연 및 추계학술발표 개요집
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• pp.74-76
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• 1994

• 한국안전학회지
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• 제16권2호
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• pp.13-21
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• 2001

The effect of water spray for the fire sprinkler depends on droples distribution over maximum possible floor area. The present study are carried out for the characteristics of water spray and droplets experimentally and numerically km two fire sprinkler heads which are CHM head and CHl heal CHl head is self-production and CHl head is widely used up to date. As the result of using CHM head, water spray and droplets are distributed over large area because CHM head has smooth surface and non-flamed shape. When the pressure of fire sprinkler head is low, SMD(sauter mean diameter) is large and when the pressure of fire sprinkler head is high, SMD is small.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1165-1169
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• 2003

This paper presents an approach to optimally design the air-bearing surface (ABS) of the optical flying head for near-field recording technology (NFR). NFR is an optical recording technology using very small beam spot size by overcoming the limit of beam diffraction. One of the most Important problems in NFR is a head disk interface (HDI) issue over the recording band during the operation. A multi-criteria optimization problem is formulated to enhance the flying performances over the entire recording band during the steady state. The optimal solution of the slider, whose target flying height is 50 nm, is automatically obtained. The flying height during the steady state operation becomes closer to the target values than those fur the initial one. The pitch and roll angles are also kept within suitable ranges over the recording band. Especially, all of the air-bearing stiffness are drastically increased by the optimized geometry of the air bearing surface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1428-1429
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• 2008

In this study the formula of electromagnetic field s by dipole antenna theory were applied to 3 phase power lines and effect of over-head earth lines was calculated and analyzed.

• 대한물리치료과학회지
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• 제30권3호
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• pp.23-30
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• 2023

Background: Flexion of cervical and lumbar joints is required when viewing a smartphone screen. Thus, these joints are overused, together with the surrounding joints and muscles. Long-term use of smartphones will cause changes in cervical and lumbar posture. The effect on forward head posture will vary, depending on the angle of cervical flexion start position in relation to the smartphone. This study investigated how forward head posture changes over time when using a smartphone at 20° and 40° cervical flexion start positions. Design: Cross-sectional study. Methods: Twenty-five subjects with a forward head posture angle of 35° or less participated in the study. A Forward Head Posture app on the participants' smartphones measured forward head posture 5 and 10 minutes after watching videos on their smartphones. Cervical range of motion was used to set a smartphone watching start posture of 20° and 40° of cervical flexion. Results: There was no significant difference in forward head posture, irrespective of cervical flexion start position, but the angle of forward head posture increased more at cervical flexion of 40° than at cervical flexion of 20°. There was no significant difference in what according to smartphone video viewing times, but the angle of forward head posture increased over time. Conclusion: An increase in forward head posture over time with smartphone usage poses a potential risk of neck and shoulder pain. Therefore, smartphone users should avoid prolonged screen time.

• 한국전문물리치료학회지
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• 제30권1호
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• pp.23-31
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• 2023

Background: Several factors contribute to shoulder pain, including abnormal neck posture, repeated use of the upper limbs, work involving raising the upper limbs above the head, and the effects of vibration. However, previous study has reported that constant vibration exposure could impact improvement of the stability on joints related with muscle recruitment and activation. For this difference reason, we need to verify for the complex study of relationship with repetitive upper limb movements, poor head posture, and constant vibration exposure. Objects: Our study was made to investigate the influence of vibration exposure on the shoulder muscle activity during forward-head and over-head tasks with isometric shoulder flexion. Methods: In a total of 22 healthy subjects, surface electromyography (EMG) data were collected from shoulder muscles (upper/lower trapezius, serratus anterior, and lumbar erector spinae) on tasks (neutral-head task [NHT], forward-head task [FHT], and over-head task [OHT]) with and without vibration exposure. Results: In all tasks, the EMG data of the upper trapezius and serratus anterior significantly increased with vibration exposure (p < 0.05). Furthermore, the EMG data of the lumbar erector spinae significantly increased with vibration exposure in the NHT and FHT (p < 0.05). Conclusion: We suggest that continuous vibration exposure during the use of hand-held tools in the tasks could be associated with harmful effects in the workplace. Lastly, we clinically need to examine the guidelines regarding the optimal posture and vibration exposure.

• 대한가정학회지
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• 제36권10호
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• pp.179-196
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• 1998

The purpose of this study was to analyze the financial status of Korean elderly households to make a financial plan for retirement preparation. The sample obtained from 1997 KHPS, consisted of 326 households of 55-64 aged and 210 households of 65 and over aged. Statistics employed for the analysis were frequencies, percentile, univariate analysis and logistic analysis. And Lorenz curve and Gini coefficient were used to compare the financial status. The results could be summarized as follows. First, total income, total expenditure, total debt and net worth of 55-64 aged group were higher than those of 65 and over group, while total asset of 55-64 aged group was similar to 65 and over group's Second, total expediture to total imcome ratio(R1) and total asset to total debt ratio(R4) of 55-64 aged group were higher than 65 and over group's, but net worth to minimum cost of living ratio(R2) and financial asset to monthly expenditure ratio(R3) of 65 and over group were higher than 55-64 aged group's . Third, R4's Gini coefficient was the highest and R1's Gini coefficient was the lowest among all Gini coefficients. Also, R1's and R4's Gini coefficients of 55-64 aged group were greater than 65 and over group's. ourth, variables affecting R1's stability of 55-64 aged group were household head's age, educatonal attainment and family type, while those of 65 and over group were household head's age, past economic experience and the number of children. There was no significant variable affecting R2's stability of 55-64 aged group, but there was only household head's pst economic experience affecting those of 65 and over group. The variable contributing to R3's stability of 55-64 aged group was residence while the variables of 65 and over group were household head's educational attainment, past economic experience and the number of children. The variables contributing to R4's stability of 55-64 aged group were the number of children and residence, and the number of children was one variable of contributing to R4's stability of 65 and over aged group.

• 한국응급구조학회지
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• 제20권1호
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• pp.7-15
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• 2016

Purpose: There are few studies on the quality of cardiopulmonary resuscitation (CPR) performed by a single rescuer using a bag-valve-mask device. The aim of this study is to compare CPR quality outcomes according to the rescuer's position or mask fixation grip method and to determine the optimal means of achieving therapeutic goals. Methods: The three CPR methods were defined as over-the-head, lateral-superior, and lateral-inferior, depending on the rescuer's position or mask fixation hand placement. CPR quality was estimated for 83 paramedic students who performed 5 minutes of CPR in a randomized sequence on a manikin using each of the three methods. Results: The over-the-head method showed no advantage for cardiac compression and ventilation quality, but minimized the rescuer's fatigue score. Conclusion: In contrast to previous studies or prevailing beliefs, the lateral-superior position is optimal for achieving therapeutic goals with moderate or minimal rescuer fatigue.

• 디자인융복합연구
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• 제17권4호
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• pp.17-29
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• 2018

완전 자율주행 단계에 이르기 전까지 부분 자율주행 차량에서는 시스템이 특정 상황에서 운전자에게 직접 운전을 하도록 요청하는 제어권 전환 요청(TOR)이 필수적이다. 이 연구의 목적은 인간-자동차 인터랙션 방식 중 HDD(Head-Down Display)보다 HUD(Head-Up Display)가 제어권 전환 요청 시 사용자 경험 인식에서 더 유리한지 비교하는 것이다. 운전 시뮬레이터 실험을 통해 참가자가 자율주행 상황에서 부가적 과업인 게임을 하다가 제어권 전환 요청을 인지하면 직접 운전을 수행하도록 하였다. 실험 결과, 반응시간과 주관적 작업 부하에서는 차이가 없었으나, '사용 용이성'과 '만족도'에서 HUD 방식이 HDD보다 더 우수한 것으로 나타났다. 자율 주행시 HUD를 통해 부가적 과업을 하도록 디자인하는 것이 제어권 전환 요청 기능의 사용자 경험을 개선하는 효과가 있었다. 이 연구는 자율주행 맥락에서의 사용자 경험 디자인 가이드라인 설정을 위한 실증 사례를 제시했다는 점에서 의의가 있다.

• 한국생산제조학회지
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• 제22권6호
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• pp.937-944
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• 2013

This paper describes an improved model that can be used for configuring a non-contact pneumatic head to handle a large sheet of glass. The cylindrical head model is of a large size (70 mm). It operates on vortex flow, which can simultaneously generate suction and repulsion over the flat object's surface. The head allows for the minimal non-contact lifting of objects weighing over 3N by using reference conditions (working pressure and head dimensions). Additionally, a functional flow-guide is applied for inducing a developing tangential vortex flow to increase suction and repulsion to the reference head. The cylindrical flow-guide is associated with relatively low tangential velocity. The improved model generates greater lifting force than the reference model, as verified experimentally.