스쿼트 현상과 스트로크의 관계

김형찬 한국교통대학교 2021 한국교통대학교 논문집 Vol.56 No.-

When a player plays billiards game, they use various stroke techniques. Simple examples are the stroke that uses only the mass of the cue and a stroke in which the player holds the cue firmly. Depending on situations, players try to bent/twist the cue up/down. Sometimes, they accelerate/decelerate the cue when it touches the billiards ball. These acts are to endow with an appropriate velocity and rotation to the ball so that the ball moves properly when it strikes another ball or cushion. In this work, we analyze the following strokes: i) The cue moves parallel to the billiard pool. ii) Its trajectory is straight. Let us compares two cues of different mass but move with the same velocity. Using a heavier cue the ball gets less squirt, faster (angular) velocity. However, one has difficulty in controlling the movement of a heavier cue than a lighter one. In addition, it is not easy to make a fast shot for the cue. In other words, the heavier cue has difficulty in making various strokes freely. An equivalent way is to use a firm grip so that the cue moves with the hand. In effect, the firm grip plays the same role as using a heavier cue, because part of the hand's mass is added to that of the cue. Therefore, players should choose a cue of an appropriate mass and use various grip methods to make such effects.

당구에서 큐의 가속이 공에 미치는 영향

김형찬 韓國交通大學校 2022 한국교통대학교 논문집 Vol.57 No.-

When players play billiards game, they use various stroke techniques. Sometimes, they accelerate/decelerate the cue when it touches the billiards ball. These acts are to endow with an appropriate velocity and rotation to the ball so that the ball moves properly when it strikes another ball or cushion. In this work, we analyze the effect of the cue acceleration on the motion of the ball.

강한 중력하의 이상기체 엔트로피 문제에 대한 이해

김형찬 한국교통대학교 2016 한국교통대학교 논문집 Vol.51 No.-

We study the entropy of an ideal gas in the presence of a strong Newtonian gravity. It is known that the entropy has a problem that the entropy logarithmically decreases to be negative for large gravity, which must be an error. In this work, we try to understand the origin of this pathology and discuss that this problem does not happen for more general physical situations.

물질의 상태방정식과 중력

김형찬 한국교통대학교 2019 한국교통대학교 논문집 Vol.54 No.-

We investigate how an equation of state for matter is affected by a self gravity. For this purpose, we consider self-gravitating  -identical particles based on the Newtonian gravity. To describe the state of the system, we use the surface values of physical parameters such as density, temperature, pressure. Assuming that the system follows an adiabatic process further, we obtain a new relation between the averaged pressure and density, which differs from the conventional equation of state for the ideal gas in the absence of gravity or in the presence of a background gravity. The problem of entropy which was present for a system in a background gravity is shown to be cured

등가속 운동하는 조화진동자로부터의 복사

김형찬 한국교통대학교 2020 한국교통대학교 논문집 Vol.55 No.-

We present an exact treatment of the influences of a uniformly accelerating harmonic oscillator on a quantum scalar field in its Minkowski vacuum state induced by minimal coupling. The exact time evolution of the quantum operators for the field and the oscillator is given by means of the Ermakov-Lewis-Riesenfeld invariant method. The exact quantization of a time-dependent oscillator coupled to a massless scalar field is given. Once the coupling jumps, the oscillator absorbs energy quickly. Then, it slowly radiates the absorbed energy into the scalar field. Especially, when the coupling is comparable to the natural frequency of the oscillator, maximal energy is radiated away.

초등 과학 교육 포트폴리오 체제의 적용이 과학 성취도와 사회심리학적 교실 환경에 미치는 효과

김찬종,조선형 청주교육대학교 과학교육연구소 2000 科學과 數學敎育論文集 Vol.21 No.-

The purpose of the study is to investigate the effects of a portfolio system on elementary school students' science achievements and classroom environment. The participants were selected from seven schools located in central parts of Korea. Two classes were selected randomly at each school, and one class was assigned to experimental group and the other to control group. The total number of participants is 475. The research use pre-post test intact group design. Little difference is found in science achievement. However, statistically significant difference is found in classroom environment. The experimental group show meaningful gain in the sub-domains such as task orientation, equity, and teacher support. Considering that the portfolio system had been administered in relatively short period of time, it has high potential for the reform of science classroom.

지능형 미소비균일체 계수기의 성능개선

조시형,박찬원 江原大學校 産業技術硏究所 2009 産業技術硏究 Vol.29 No.B

This paper presents the development of smart counting system that is proper for grains with uneven unit weight or shape. This device can detect the small differences of a light beam and count the pulse from wave shape control, when the grain is going on the light screen, which is made by the light beam screen sensor. It can, different from the former conventional device, distinct the uneven grains for counting detect, by using the dedicated hardware and the software algorithm of the light sensor.

제주도 감귤원 토양의 V.A-mycorrhizae분포 및 사상균에 의한 인광석의 용해에 관한 연구

김형옥,유장걸,이신찬,R.M.N. Kucey 제주대학교 1984 논문집 Vol.17 No.-

The mycorrhizae spore densities (spore numbers/100g soil) were measured on six sites of citrus field by the floating method to estimate the mycorrhizae distniution on volcanic ash soil in Jejudo. Phosphate solubilizing fungi and bacteria in the soils were isolated and selected by the succesive pure culture in the potato dextrose agarcalcium phosphate (PDA-P) media. The phosphate solubilizing capacities of the sele-cted fungi were measured after incubating in the liquid media mixed with 200 mg of powdered rock phos-phate for one week. 1. The highest spore density (456/100g soil) was observed in the soil from the 6 years citrus field located on Samyangdong, Jeju-si and the next one (385/100g soil) from the 18 years citrus field at the same place. The soils from Topyeongdong, Seogwipo-si (1)(2) were found to contain lower mycorrhizae spores than other sampling sites, 256/100g soil at seven years citrus field and 166/10g soil at twenty one years citrus field. 2. Colony radii and halo radii of bacteria measured 4mm - 11mm and 6mm-22mm, and colony radii and halo radii of fungi were 8mm-12mm and 14mm-18mm respectively when they were incubated in PDA-P media for one week. 3. The selected fungi, based on the radius size of colony and halo, dissolved 0.46mg-2.64mg P_(2)0_(3) from 200mg of powdered rock phosphate in the liquid media.

상악동에 발생한 거대한 Cholesterol 육아종 1례

김승찬,박형욱,김용기,나한조,도남용 朝鮮大學校 附設 醫學硏究所 1991 The Medical Journal of Chosun University Vol.16 No.1

The cholesterol granuloma is not a specific clinical or pathologic entity but merely a term used to describe a tissue response to cholesterol crystal. The cholesterol granuloma in paranasal sinuses is rare disease. Recently the authors had experienced a case of huge cholesterol granuloma, which involved the right maxillary sinus. The cholesterol granuloma was removed successfully by mean of enucleation through the Caldwell-Luc approach. So, we report a case with brief review of the literature.

牧楡湯이 人體 肺癌細胞의 變化에 미치는 影響에 關한 分子生物學的 硏究

李炯周,金相贊,徐富一,金先熙,卞晟僖 대한본초학회 1999 大韓本草學會誌 Vol.14 No.1

This experimental study was performed to investigate the effects of Mokyou-Tang on cell cycle and gene expressions of human lung cancer cell. I examined the cell cycle progression and cell cycle-related gene expression in A549 using a flow cytometry and a quantitative PT-PCR analysis. The treatment groups, in accordance with concentration of Mokyou-Tang were classified as 3 group(MYT 100㎕/㎖, MYT 500㎕/㎖, MYT 1,000㎕/㎖), and according to treatment time, were classified as 2 group(24hours, 48hours). The results were summarized as follows; 1. In cell cycle stage, MYT 100㎕/㎖(48hours) and 1000㎕/㎖(48hours) groups were increased as compared with control group, especially 1000㎕/㎖(48hours) group showed eminent increase. 2. In p53 gene, MYT 500㎕/㎖(48hours) and 1000㎕/㎖(48hours) groups showed eminent suppressive effect to cancer cell. 4. CDKNI gene was decreased in all treatment groups, this mean that MYT has suppressive effect to proliferation of cancer cell. 4. In GADD45 gene was decreased in all treatment groups, this mean that MYT has suppressive effect to proliferation of cancer cell. The results suggest that MYT promotes G1 cell cycle arrest and suppresses the proliferation of cancer cell. Thus, it seems likely that MYT has suppressive effect to proliferation of lung cancer cell.