• Journal of Ecology and Environment
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• 제41권10호
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• pp.281-289
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• 2017

Background: In this study, the growth and reproductive response of seedlings, grown in plastic pots with sand, to moisture and nutrients were analyzed in order to study the environmental conditions required to create an alternative habitat for Epilobium hirsutum L., an endangered plant. Results: Vegetative and reproductive growths of Epilobium hirsutum L. are accelerated with increase in moisture and organic matter content in the soil. Among vegetative organs, the number of runners related to asexual reproduction was the highest when the moisture content was over 25% and nutrient content between 7 and 14% in the soil. But the number of flowers related to flowering responses, among reproductive organs, was the highest when the moisture content was maintained at 75% and when nutrient content was 21% in the soil. The number of seeds, related to sexual reproduction, was the highest when the moisture content was over 25% and nutrient content between 14 and 21%. Conclusions: The study results show that a place with high moisture and nutrient content in the soil is advantageous to asexual and sexual reproduction of Epilobium hirsutum L. Therefore, we must serve periodically nutrient and seeds to sustain population in in situ conservation. Furthermore, it is advisable to create in riverside where abundant nutrient content have, making alternative habitat of Epilobium hirsutum L. Also, we must find species that have high contribution degree index through vegetation survey.

• 응용통계연구
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• 제29권2호
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• pp.321-330
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• 2016

감독이 작전을 구사하는 상황이나 타자의 타격 가치를 평가하는데 유용하게 사용될 수 있는 지표로서 미국프로야구에 대해서는 기대득점과 기대승리확률, 타격의 득점가치, 타격의 승리가치 등이 제시되었다. 기대득점은 각각의 아웃카운트와 주자 상황에서 그 이닝이 끝날 때까지 얻는 점수의 기댓값이다. 기대승리확률은 이닝, 점수차, 아웃카운트, 주자상태가 주어진 상태에서 경기를 계속 한다고 할 때, 공격하고 있는 팀이 승리할 확률이다. 타격의 득점가치는 타격전 상황의 기대득점과 타격결과에 의하여 변화된 상황의 기대득점 사이의 차이를 말한다. 타격의 승리가치는 타격 전후 상황의 기대승리확률간의 차이로서 타격 결과가 승리에 미치는 영향을 나타낸다. 한국프로야구에서는 장기간 축적된 자료의 부족으로 총 발생횟수에 대한 특정 상황의 상대돗수를 이용하여 구한 이들 지표가 통계적인 의미를 갖지 못하는 경우가 종종 나타난다. 이와 같은 문제점을 극복하기 위하여 본 논문에서는 마르코프연쇄를 이용하여 한국프로야구에서 기대득점, 기대승리확률, 득점가치와 승리가치를 구하는 방법을 제시한다.

• 한국운동역학회지
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• 제18권3호
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• pp.93-105
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• 2008

본 연구는 스타팅 블록 유형에 따른 운동학적 변인을 분석하기 위하여 남자 단거리 선수 8명을 대상으로 스타팅 블록간의 거리를 세 가지(25cm, 40cm, 35cm)유형으로 구분하여 분석하였다. 본 연구에 참여한 평균 신장 180cm의 선수들에게는 출발선과 앞 블록의 거리 45cm, 블록간의 거리 40cm의 출발 유형이 100m 기록 단축을 위해서 유리한 스타팅 블록의 유형이라 할 수 있다. 이상의 결론을 종합해보면 100m 출발은 정지 상태에서 짧은 시간에 가능한 큰 추진력을 얻는 데 있으며, 중요한 기술적 요점은 출발 신호에 재빠르게 반응하고, 강한 킥에 의해 큰 추진력을 얻어 전경각과 중력을 잘 이용하여 빠른 시간 내에 최고의 속도에 도달하는데 있다. 본 연구에서는 B유형의 출발법이 기록 향상을 위해 효과적인 분석 결과를 보여주고 있다.

• 한국운동역학회지
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• 제30권2호
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• pp.145-154
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• 2020

Objective: The purpose of this study was to determine the relationship between impact and shear peak force, and tibia-accelerometer variables during running. Method: Twenty-five male heel strike runners (mean age: 23.5±3.6 yrs, mean height: 176.3±3.3 m/s, mean mass: 71.8±9.7 kg) were recruited in this study. The peak impact and anteroposterior shear forces during treadmill running (Bertec, USA) were collected, and impact shock variables were computed by using a triaxial accelerometer (Noraxon, USA). One-way ANOVA was used to test the influence of the running speed on the parameters. Pearson's partial correlation was used to investigate the relationship between the peak impact and shear force, and accelerometer variables. Results: The running speed affected the peak impact and posterior shear force, time, slope, and peak vertical and resultant tibial acceleration, slope at heel contact. Significant correlations were noticed between the peak impact force and peak vertical and resultant tibia acceleration, and between peak impact average slope and peak vertical and resultant tibia acceleration average slope, and between posterior peak (FyP) and peak vertical tibia acceleration, and between posterior peak instantaneous slop and peak vertical tibial acceleration during running at 3 m/s. However, it was observed that correlations between peak impact average slope and peak vertical tibia acceleration average slope, between posterior peak time and peak vertical and resultant tibia acceleration time, between posterior peak instantaneous slope and peak vertical tibial acceleration instantaneous slope during running at 4 m/s. Conclusion: Careful analysis is required when investigating the linear relationship between the impact and shear force, and tibia accelerometer components during relatively fast running speed.

• 한국산학기술학회논문지
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• 제15권5호
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• pp.2635-2640
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• 2014

리 릿나워와 래리 칼튼은 같은 세대를 풍미한 기타리스트이다. 그런 만큼 둘의 공통점을 찾아볼 수 있다. 또한 많은 경험과 노하우로 본인들의 음악을 퓨전 재즈라는 장르로 완성 시켰다. 퓨전이라는 장르의 특성을 살려 늘 새로운 시도를 해왔고, 시대적 상황에 맞춰 음악적 융합을 만들어 내는 컨템포러리 재즈(Contemporary Jazz)의 선두주자 임을 알 수 있다. 재즈라는 장르로 예술성과 상업성을 이룬 이 두 기타리스트의 업적은 매우 의미가 있다. 같은 장르, 같은 파트의 뮤지션이 이 같은 성공을 이룰 수 있었다는 것은 본인들의 음악적 표현 방식이 많은 사람들에게 공감을 주었다는 것이다. 본 논문에서는 이 두 기타리스트의 작품에서 나타나는 화성적인 부분과 편곡적인 부분을 분석하고, 이들의 대표적인 앨범이 가지고 있는 의미와 음악적 방향들을 살펴보았다. 그리고 이 두 기타리스트의 관계를 통해 어떠한 음악적 성장이 있었는지 중점을 두고 분석 했다.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.589-596
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• 2021

In this study, the optimum gating system was designed, and the two zinc alloy worm gears were manufactured in single process by applying a symmetrical gating system with 2 runners. The SRG ratio is set to 1 : 0.9 : 0.6, and the cross-sectional shapes such as sprue, runner and gate are designed. In order to determine whether the design of the gating system is appropriate, casting analysis was carried out. It takes 4.380 s to charge the casting 100%, 0.55 to 0.6 m/s at the gates and solidification begins after the casting is fully charged. The amount of air entrapment is 2% in the left gear and 6% in the right gear. Hot spots occurred in the center hole of the gear, and pores were found to occur around the upper part of the hole. Therefore, the design of the casting method is suitable for worm gears. CT analysis showed that all parts of worm gear were distributed with fine pores and some coarse pores were distributed around the central hole of worm gear. The yield strength and tensile strength were 220 MPa, 285 MPa, and the elongation rate was 8%. Vickers hardness is 82 HV.

• 대한스포츠의학회지
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• 제36권4호
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• pp.214-220
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• 2018

Purpose: The purpose of this research is to study changes in pituitary hormone in anterior lobe and thyroid hormone before, after, and during recovery time in severe 100 km ultramarathon. Methods: Healthy middle-aged runners (age, $52.0{\pm}4.8$ years) participated in the test. Grade exercise test is done, and then blood is taken from those participants before and after completing 100 km ultramarathon at the intervals of 24 hours (1 day), 72 hours (3 days), and 120 hours (5 days) to analyze their luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), and free thyroxine (Free T4). Results: For LH, it decreased more significantly at 100 km than pre-race. However, after 1 day result increased more than that of 100 km. At 3 days, it was significantly higher than pre-race and 100 km, recovering at 5 days. In terms of FSH, it decreased at 100 km, 1 day, and 3 days more than pre-race but recovered at 5 days. TSH was higher at 1 day and 5 days compared to pre-race. T3 was only higher at 100 km than pre-race. T4 was higher till 5 days at 100 km than pre-race. Free T4 increased more significantly at 100 km than pre-race. Conclusion: In terms of severe long distance running, LH and FSH which belong to hormone from anterior lobe as well as T3, T4, and Free T4 which belong to thyroid hormone showed their variation within the standard range. However, TSH showed abnormal increase from enhanced concentration of blood after marathon becoming hyper-activation even during the recovery period.

• Safety and Health at Work
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• 제12권2호
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• pp.147-153
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• 2021

Background: In this study, the association of work and demographic characteristics with different traffic offenses committed by food delivery riders in Greece was examined. Previous research has identified various factors related to risky driving however, there is a need for exploring the complex interrelationship of work-related factors underlying risky driving behavior. Materials and Methods: A 2-items uestionnaire was used exploring delivery riders demographic characteristics, terms of employment, issues of concern during work and type of traffic offenses committed. In total, uestionnaires were analyzed using logistic regression in order to identify characteristics independently associated with serious traffic offenses, namely, red-light running and helmet non-use. Results: The analysis showed that: (i) typical health and safety measures had no effect on serious traffic offenses, (ii) young age was related to both offenses however (iii) different sets of work conditions were associated with reports of red-light running (i.e. low work experience, use of personal vehicle for work, and payment by hour) and helmet non-use respectively (i.e. intense work pace, high tip income per day and low concern about vehicle condition). Conclusion: The above findings provide evidence that serious traffic offenses are manifestations of underlying conflict experienced by the riders between safety and various performance criteria. Each one of the two offenses is related to different rider profiles aiming to satisfy different goals, namely, those mainly trying to maximize profit non-helmet users and those, mostly inexperienced ones, trying to cope with work pressure red light runners. Potential regulatory measures to alleviate risky practices are discussed.

• 운동영양학회지
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• 제25권3호
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• pp.16-22
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• 2021

[Purpose] Exercise-associated hyponatremia (EAH) is a well-known condition among endurance athletes at low altitudes. The incidence of EAH during ultramarathons at high altitudes warrants further investigation. This prospective observational study was conducted on the participants of the Leadville Trail 100 run, a 161-km race held at a high altitude (2,800 m-3,840 m). [Methods] Venous blood samples were collected before and immediately after the race. The participants completed an electronic survey after the race. Our main outcome measure was the post-race serum sodium ([Na⁺]) level. [Results] Of the 672 athletes who started the race, 351 (52%) successfully completed the event within the 30-hour cut-off. Post-race blood samples were collected from 84 runners (66 finishers). Both pre- and post-race blood samples were collected from 37 participants. Twenty percent of the post-race participants had EAH. Only one post-race participant had a [Na⁺] level of <130 mmol/L. All participants with EAH were asymptomatic. One participant had an abnormal pre-race [Na⁺] level (134 mmol/L). Female participants had a significantly higher rate of EAH than male participants (40% vs. 16%; p=0.039). Age, body mass index, weight changes, race completion status, nonsteroidal anti-inflammatory drug use, and urine specific gravity were not associated with the development of EAH. Lower postrace [Na⁺] levels were associated with higher serum creatine kinase values (R²=0.1, p<0.005). [Conclusion] High altitude (3,840 m peak) does not appear to enhance the incidence of EAH after an ultramarathon footrace. This suggests that ambient temperature (low temperatures reduce risk), sex (female predilection), endurance running, and overhydration are more prominent risk factors for EAH than high altitude.

• Tribology and Lubricants
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• 제39권2호
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• pp.81-85
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• 2023

This study presents an experimental investigation of the effects of surface roughness on gas foil thrust bearing (GFTB) performance. A high-speed motor with the maximum speed of 80 krpm rotates a thrust runner and a pneumatic cylinder applies static loads to the test GFTB. When the motor speed increases and reaches a specific speed at which a hydrodynamic film pressure generated within the gap between the thrust runner and test GFTB is enough to support the applied static load, the thrust runner lifts off from the test GFTB and the friction mechanism changes from the boundary lubrication to the hydrodynamic lubrication. The experiment shows a series of lift-off test and load-carrying capacity test for two thrust runners with different surface roughnesses. For a constant static load of 15 N, thrust runner A with its lower surface roughness exhibits a higher start-up torque but lower lift-off torque than thrust runner B with a higher surface roughness. The load capacity test at a rotor speed of 60 krpm reveals that runner A results in a higher maximum load capacity than runner B. Runner A also shows a lower drag torque, friction coefficient, and bearing temperature than runner B at constant static loads. The results imply that maintaining a consistent surface roughness for a thrust runner may improve its static GFTB performance.