• 한국운동역학회지
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• 제25권2호
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• pp.149-155
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• 2015

Purpose : Recently, many researchers and golf coachers demonstrated that X-factor and X-factor stretch had a co-relationship with driving distance. However, its relationship is still controversial and ambiguous. Thus, the aim of this study was to examine the relationship among X-factor, X-factor stretch and swing-related factors, including driving distance in elite golfers. Method : Seventeen male elite golfers (handicap: ${\leq}4$) with no history of musculo-skeletal injuries participated in the study. Thirty spherical retro-reflective markers were placed on including the middle point of PSIS, the right/left ASIS, the right/left lateral acromion of the scapula, driver head and shaft grip. All motion capture data was collected at 100Hz using 6 infrared cameras. Carry distance, club speed, ball speed, smash factor, launch angle, and spin rate were collected from radar-based device, TrackMan. Results : Pearson's correlation coefficient method was used to find the correlations among X-factor, X-factor stretch and swing-related factors. Positive correlations between driving distance and other swing-related factors which include club speed(r=.798, p<.001), and ball speed(r=.948, p<.001) were observed. In contrast to the swing-related factors, X-factor and X-factor stretch had no relationship to driving distance. Conclusion : These results indicate that X-factor and X-factor stretch are not key regulators in driving distance.

• 한국철도학회논문집
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• 제10권5호
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• pp.582-588
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• 2007

분기기 시스템은 기존선의 속도향상을 저해하는 요소들 중에 하나이며, 우리나라에서는 안전을 위하여 분기기 직선측 통과속도를 130km/h로 제한하고 있어 기존선 속도향상을 위해서는 반드시 개선되어야할 사항이다. 본 연구에서는 기존 및 개량 분기기 궤도 성능을 평가 기 위해 동적윤중 현장계측 데이터를 이용하여 충격계수가 산정되었으며, 수치해석을 이용하여 분기기 하부 노반의 지지력을 평가하였다. 그 결과 분기기 개선에 따른 노반응력 저감효과를 확인 할 수 있었으며, 기존 및 개량 분기기에서 발생한 노반응력은 허용지지력 이하로 나타났다.

• 한국운동역학회지
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• 제22권3호
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• pp.269-276
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• 2012

The purpose of This study's aim is to examine the difference in the changes of body segment movement, variables for ball quality, and carry at golf driver swing according to the ball quality using comparative analysis. Regarding the impact variables according to the ball quality using the track man and carry, club speed was the fastest at draw shot, ball speed was the fastest at straight shot, and smash factor was the lowest at draw shot. About the vertical launch angle, the fade shot showed the highest launch angle while the max height of the ground and ball was the highest at fade shot. And carry was the longest at draw shot. For the flight time, it was the longest at draw shot. The landing angle was the largest at fade shot. About the club head position change and trajectory, at the overall event point, the fade shot drew a more outer trajectory at the point of the follow through(E6) than the straight or draw shot. Regarding the angular speed of shoulder rotation, at the overall event point, the fade shot showed the greatest angular speed change in the follow through(E6). Also, about the angular speed of pelvic rotation, at the overall event point, the draw shot showed the greatest angular speed change at the point of down swing(E4). Concerning the stance angle change, both straight and fade shots were open as the concept of open stance whereas the draw shot was close as that of close stance. Regarding the previous study, the most important factor of deciding Ball Quality is the club face angle's open and close state at Impact. In short, the Ball Quality and carry were decided by this factor.

• International Journal of Advanced Culture Technology
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• 제11권4호
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• pp.302-309
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• 2023

Wearable devices, attached to the human body, track and enhance users' activities, health, and communication. Therefore, considering ergonomic factors in product design is crucial. However, previous research has somewhat overlooked the importance of integrating ergonomic design elements into a broad spectrum of design factors. This study aims to examine the impact of physical attributes inherent in smart wristbands and smartwatches on the perceived functional value, specifically, perceived usefulness, ease of use, and fit. A survey was conducted among 289 US adults who had experience using smart wristbands or smartwatches. The collected data were analyzed using descriptive statistics, factor analysis, Cronbach's alpha, t-test, MANOVA, and regression analysis in SPSS version 29. The results showed that the shape of the front display significantly influenced perceived ease of use, and the product's weight had a substantial impact on both perceived ease of use and fit. Furthermore, distinct technical features on the front display had varied effects on perceived usefulness, ease of use, and fit. Notably, the presence of activity tracking, alarm, and calendar functionalities led to distinct differences in ease of use and fit. Features such as distance tracking, phone call, social media notifications, text messaging, and time display functions showed significant influences on the perception of fit. These findings provide insights into the physical values of smart wristbands and smartwatches as perceived by users.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.259-269
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• 2017

Gust load is a very important load factor in designing various structures of an aircraft and judging its stability. This is because the blast effect on the aircraft in operation increases the risk of damage to the structure of the aircraft and causes a negative impact such as shortening the fatigue life by generating vibration. Particularly in the case of wing, a change in angle of attack is caused by gust load, and an additional lift acts on the wing, thereby being exposed to various excitational environments. Severe structural damage to the aircraft may occur if the natural frequencies of the aircraft wing are close to or coincident with the frequencies of the gust load applied to the wing. Recent trends of research include flight dynamics analysis considering discontinuous gusts or structural optimization of the blades under gust load. A number of studies have been conducted to interpret gust load response in consideration of irregularities in gusts. In this paper, we tried to imagine the situation of the aircraft subjected to the gust load as realistic as possible, and proposed an algorithm to track back the critical gust profile according to given aircraft characteristics from the viewpoint of preliminary engineering prediction.

• 자동차안전학회지
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• 제14권4호
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• pp.70-76
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• 2022

This paper investigates the effects of age, gender, and situational factors on take-over performance in automated driving. The existing automated driving systems still consider a driver as a fallback-ready user who is receptive to take-over requests. Thus, we need to understand the impact of situations and human factors on take-over performance. 34 drivers drove on a simulated track, consisting of one baseline and four event scenarios. The data, including the brake reaction time and the standard deviation of lane position, and physiological data, including the heart rate and skin conductance, were collected. The analysis was performed using repeated-measures ANOVA. The results showed that there were significant age, gender, and situational differences in the takeover performance and mental workload. Findings from this study indicated that older drivers may face risks due to their degraded driving performance, and female drivers may have a negative experience on automated driving.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4096-4101
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• 2023

Radon is a radioactive gas produced from the uranium-238 series. Radon gas affects public health and is the second cause of lung cancer. The study samples were collected from one area of the city of Jazan, southwest of the Kingdom of Saudi Arabia. The influence of engineering and physical parameters on the emanation coefficient of gas and other gas parameters was studied. Parameters for radon were measured using a CR-39 Solid-State Nuclear Track Detector (SSNTD) through a sealed emission container. The results showed that the emanation coefficient was affected directly by the change in the grain size of the soil. All parameters of measured radon gas have the same behavior as the emanation coefficient. The relationship between particle size and emanation coefficient showed a good correlation. The values of the emanation coefficient were inversely affected by the mass of the sample, and the rest of the parameters showed an inverse behavior. The results showed that increasing the volume of the container increases the accumulation of radon sons on the wall of the container, which increases the emission factor. The rest of the parameters of radon gas showed an inverse behavior with increasing container size. The results concluded that changing the engineering and physical parameters has a significant impact on both the emanation coefficient and all radon parameters. The emanation coefficient affects the values of the radiation dose of an alpha particle.

• 대기
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• 제23권2호
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• pp.205-220
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• 2013

Upper ocean response to typhoon Ewiniar (0603) and its impact on the following typhoon Bilis (0604) are investigated using observational data and numerical experiments. Data used in this study are obtained from the Ieodo Ocean Research Station (IORS), ARGO, and satellite. Numerical simulations are conducted using 3-dimensional Princeton Ocean Model. Results show that when Ewiniar passes over the western North Pacific, unique oceanic responses are found at two places, One is in East China Sea near Taiwan and another is in the vicinity of IORS. The latter are characterized by a strong sea surface cooling (SSC), $6^{\circ}C$ and $11^{\circ}C$ in simulation and observation, under the condition of typhoon with a fast translation speed (8m $s^{-1}$) and lowering intensity (970 hPa). The record-breaking strong SSC is caused by the Yellow Sea Bottom Cold Water, which produces a strong vertical temperature gradient within a shallow depth of Yellow Sea. The former are also characterized by a strong SSC, $7.5^{\circ}C$ in simulation, with a additional cooling of $4.5^{\circ}C$ after a storm's passage mainly due to enhanced and maintained upwelling process by the resonance coupling of storm translation speed and the gravest mode internal wave phase speed. The numerical simulation reveals that the Ewiniar produced a unfavorable upper-ocean thermal condition, which eventually inhibited the intensification of the following typhoon Bilis. Statistics show that 9% of the typhoons in western North Pacific are influenced by cold wakes produced by a proceeding typhoon. These overall results demonstrate that upper ocean response to a typhoon even after the passage is also important factor to be considered for an accurate intensity prediction of a following typhoon with similar track.

• 디지털융복합연구
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• 제18권9호
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• pp.125-133
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• 2020

본 연구는 중소 제조기업의 스마트 팩토리 구축 관련 대표 및 직원역량과 스마트 팩토리 수용의도 그리고 경영성과 사이의 영향관계를 확인하고 중소 제조기업의 스마트 팩토리 도입과 관련한 전략적 함의를 도출하기 위해 실시하였다. 중소 제조기업 중 스마트 팩토리를 도입한 기업을 대상으로 설문조사를 통해 수집된 310부의 자료를 바탕으로 요인분석, 신뢰성 및 타당성 분석을 실시하여 최종 확정된 연구 모형에 대해 구조방정식모형(SEM)분석으로 연구가설 검정을 실시하였다. 연구 결과, 대표 및 직원역량은 스마트 팩토리 수용의도에 유의한 영향을 미치고, 직원역량은 경영성과에 유의한 영향을 미치는 것을 확인되었다. 수용의도는 경영성과에 정의 영향을 미치고, 지역특성은 대표역량, 수용의도 및 경영성과 사이의 관계에 조절효과가 있는 것으로 확인되었다. 본 연구를 통해 기업역량은 스마트 팩토리 수용의도에 영향을 주는 주요 요인이며, 지역특성은 대표역량과 스마트 팩토리 도입의도 그리고 경영성과 간의 경로에 유의한 조절작용을 하는 것으로 나타났다. 향후 중소 제조기업 스마트 팩토리 수준별 연구와 업종, 규모에 따른 스마트 팩토리 도입기업의 특성 연구가 요구된다.

• 문화기술의 융합
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• 제8권5호
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• pp.515-524
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• 2022

도시철도 침목플로팅궤도(STEDEF)의 분기기는 콘크리트 도상에 매입된 목침목과 침목 하부의 침목방진패드로 구성된 방진궤도로서 침목방진패드의 열화 및 이에 따른 스프링강성의 변화가 침목지지조건의 변화를 초래할 수 있다. 현재 약 21년의 공용기간 동안 발생된 망간크로싱의 손상수량은 전체 부설수량 대비 약 17%로 조사되었으며, 사용 기간 15년 이후(누적통과톤수 약 5.5억톤)부터 손상 물량이 증가하는 것으로 분석되었다. 본 연구에서는 실물 망간크로싱과 차륜의 형상을 모사한 3차원 수치모델을 이용한 매개변수 해석(차륜의 위치, 침목지지조건 및 동적 윤중의 크기)을 수행하여 실제 현장에서 발생된 망간크로싱의 손상유형 및 발생원인을 분석하였다. 연구결과, 노즈부 주변 침목에 뜬침목이 발생된 경우, 설계 궤도충격계수가 적용된 동적윤중 작용 시 노즈부 단면의 발생응력이 항복강도를 초과하였으며, 이는 실제 현장에서 발생된 손상위치와 비교적 잘 일치하는 것으로 분석되었다. 따라서 망간크로싱의 손상을 최소화하기 위해서는 노즈부 주변의 침목지지조건을 일정한 수준으로 유지하고, 손상된 망간크로싱 교체 시에는 침목 하부 경계조건의 균일성 확보를 위해 침목방진패드를 함께 교체하는 것이 바람직할 것으로 분석되었다.