• International Journal of Internet, Broadcasting and Communication
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• 제13권1호
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• pp.143-151
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• 2021

The purpose of our study is to confirm the trend of the muscle activity of the trunk and lower limb muscles by the attack method and phase during volleyball exercise. To achieve this purpose, spike serve and spike were conducted for 9 male middle school students, and at that time, it was divided into four phase, such as run jump, take off, impact, and follow, and the rectus abdominis, erector spine, and left rectus femoris, left biceps femoris, left anterior tibialis, left gastrocnemius midialis, right rectus femoris, right biceps femoris, right anterior tibialis, right gastrocnemius midialis, were examined. Spike serve and spike were each performed three times, and randomly cross-allocated to extract accurate data. We was no difference in all muscles according to the attack method, and the muscle activity of the rectus abdominis was highest in the impact phase and the muscle activity of the vertebral spine muscle was highest in the close-up phase. In addition, all of the measured left and right lower limb muscles showed the highest muscle activity between the assisted devices. As a result, We found out that regardless of the method of spike serve and spike, the lower limbs in the run-up phase for a high jump, the vertebrae in the take off phase, the preparation phase for hitting the ball strongly, and in the impact phase at the moment of hitting the ball. It can be seen that it exerts the greatest power in the rectus abdominis.

• 한국운동역학회지
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• 제19권4호
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• pp.671-680
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• 2009

본 연구는 실제 경기에서 프로 배구선수 스파이크 서브의 성공과 실패 동작을 3차원 영상분석을 통해 비교 분석하여 과학적인 자료를 현장에 제공하고, 기술의 향상에 기여하고자 실시하였다. 스파이크서브를 수행하는 3명을 대상으로 카메라 4대를 이용하여 60 fields/s의 속도로 촬영하였다. 3차원좌표의 계산은 DLT(Direct Linear Transformation)방법을 사용하였으며, Kwon3D(v.3.1) 프로그램을 이용하여 분석하였으며, 그 결과 다음과 같은 결론을 얻었다. 총 소요시간은 구간별 차이가 나타나지 않았다. 신체중심 수직위치는 성공 시 1.87 m로 실패 시의 1.91 m 보다 낮게 나타났고, 최대 볼 높이는 성공 시 6.31m로 실패 시의 6.42m 보다 낮은 볼 위치를 나타냈다. 임팩트 시점의 손 높이는 성공과 실패 시기에서 차이가 나타나지 않았다. 점프하기 직전까지 신체중심의 전후속도를 높였다가 점프하는 시점에서 수직속도로 빠르게 이동시키는 것으로 나타났고, 임팩트 시 손 속도(17.11m/s)와 임팩트 직후 볼 속도(23.74m/s)는 성공 시기에서 빠르게 나타났다. 성공 시기에서 견관절을 신전시키면서 타점을 놀게 하고, 주관절은 적절한 각도를 유지시키면서 빠르고 정확한 임팩트를 하는 것으로 나타났다. 또한, 동체를 전후로 크게 움직이지 않고 어깨의 회전을 원활하게 하는 것이 중요한 것으로 나타났다.

• The Korean Journal of Physiology and Pharmacology
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• 제3권2호
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• pp.119-125
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• 1999

Mammalian gastric smooth muscles generate spontaneous rhythmic contractions which are associated with slow oscillatory potentials (slow waves) and spike potentials. Spike potentials are blocked by organic $Ca^{2+}-antagonists,$ indicating that these result from the activation of L-type $Ca^{2+}-channel.$ However, the cellular mechanisms underlying the generation of slow wave remain unclear. Slow waves are insensitive to $Ca^{2+}-antagonists$ but are blocked by metabolic inhibitors or low temperature. Recently it has been suggested that Interstitial Cells of Cajal (ICC) serve as pacemaker cells and a slow wave reflects the coordinated behavior of both ICC and smooth muscle cells. Small segments of circular smooth muscle isolated from antrum of the guinea-pig stomach generated two types of electrical events; irregular small amplitude (1 to 7 mV) of transient depolarization and larger amplitude (20 to 30 mV) of slow depolarization (regenerative potential). Transient depolarization occurred irregularly and membrane depolarization increased their frequency. Regenerative potentials were generated rhythmically and appeared to result from summed transient depolarizations. Spike potentials, sensitive to nifedipine, were generated on the peaks of regenerative potentials. Depolarization of the membrane evoked regenerative potentials with long latencies (1 to 2 s). These potentials had long partial refractory periods (15 to 20 s). They were inhibited by low concentrations of caffeine, perhaps reflecting either depletion of $Ca^{2+}$ from SR or inhibition of InsP3 receptors, by buffering $Ca^{2+}$ to low levels with BAPTA or by depleting $Ca^{2+}$ from SR with CPA. They persisted in the presence of $Ca^{2+}-sensitive$ $Cl^--channel$ blockers, niflumic acid and DIDS or $Co^{2+},$ a non selective $Ca^{2+}-channel$ blocker. These results suggest that spontaneous activity of gastric smooth muscle results from $Ca^{2+}$ release from SR, followed by activation of $Ca^{2+}-dependent$ ion channels other than $Cl^-$ channels, with the release of $Ca^{2+}$ from SR being triggered by membrane depolarization.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.303-303
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• 2022

The purpose of this study was to evaluate agronomic characteristics and identify the useful traits to utilize the wheat genetic resources for breeding programs by understanding the phenotypic variation among germplasm through multivariate analysis. In this study, a total of 394 wheat accessions were characterized for 15 agronomic traits using the National Agrobiodiversity Center (NAC) descriptor list, of which 31 accessions from 6 species and 363 unidentified accession (Triticum spp.) available at the NAC, Rural Development Administration (RDA), Korea. Growth characteristics such as leaf width, culm length, spike length, spikelet length, solid stemmed, days to heading, days to maturity, grain-filing period, and also seed characteristics such as width, height, area, perimeter, circle, solidity, and germination percent were studied. Among the 15 agronomic characteristics, the germination percent showed the smallest variation between resources (CV = 0.4%), and the spikelet length (CV = 66.5%) showed the highest variation. A strong positive correlation was found between seed traits such as seed height and seed area (r = 0.90), seed height and seed perimeter (r = 0.87) and seed length and width (r = 0.80). Principal component analysis (PCA) was conducted and the first five principal components comprised 76.7% of the total variance. Among the first five PCs, PCI accounted for 28.5% and PC2 for 20.0%. Wheat resources (394) were classified into four clusters based on cluster analysis, consisting of 215 resources(I), 117 resources(II), 48 resources(III), and 14 resources(IV). Among the clusters, the resources belonging to Cluster III showed the lowest seed width, height, area, and perimeter characteristics compared to other clusters. The wheat resources belonging to cluster IV had small seed width and low germination percent, but took longer to form heads and mature than resources in other clusters. These results will serve as the basis for further genetic diversity studies, and important agronomic characteristics will be used for improving wheat, including developing high-yielding and resistant varieties to biotic and abiotic stresses via breeding programs.

• 한국수자원학회논문집
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• 제56권3호
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• pp.225-233
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• 2023

도시하천은 급속한 경제성장과 개발 등 여건변화로 본연의 모습과 가치를 잃고 인공적인 모습으로 변해왔다. 이로 인해 도시민의 삶의 질과 만족도 또한 하락되고 있다. 본 연구에서는 부산의 대표적 도시하천인 수영강을 대상으로 도시하천 수질 개선을 위한 도시민의 지불의사액을 추정하였다. 비시장가치 추정을 위해 조건부가치측정법(Contingent Valuation Method, CVM)을 적용하여 수질개선을 위한 지불의사액(Willingness To Pay, WTP)를 파악하고 경제적 가치를 추정하였다. 가상시나리오는 EPA, 수질사다리(waterquality ladder)의 개념을 이용하여 현재 수영강 수질이 오염된 물(4등급)이라고 가상시장을 설정하고 낚시가 가능한 수준(2등급)까지 개선을 시키고자 할 때의 지불의사를 조사하였다. 이때 지불수단은 기부금의 형태로 지불기간은 연 1회 향후 5년간으로 설정하였다. WTP는 한국개발연구원(Korea Development Institute, KDI)에서 제시하고 있는 로지스틱 분포와 스파이크 모형을 사용하여 추정하였다. 지불의사 추정결과 수영강 인접 지역주민의 지불의사가 상대적으로 높게 추정되었다. 또한 부산시민의 절반 이상(56.5%)이 '자연 및 생태보전'을 수영강의 주요 기능으로 인지하고 있음을 고려할 때, 하천환경개선을 위한 지불의사의 상승은 도시하천의 가치 향상을 위한 정책적 의사결정 기준으로 작용할 것으로 판단된다. 또한 도시민의 삶의 질 향상 기대수준 충족과 더불어 도시하천 경제적 가치상승을 위한 재원 조달 방안을 마련할 수 있을 것이다.