사이클링 선수의 슬관절각에 따른 하지동작의 운동학적 분석

류창엽,최성진,박종진,강순용 한국운동역학회 2001 한국운동역학회지 Vol.11 No.3

This study set out to evaluate the appropriateness of the height of a cycle saddle which was usually set based on a cyclist's experience and simple judgment. For this purpose, there was aroused a need to study what a cyclist's leg movements were according to the knee joint angle, that is, to study how a cyclist's leg joint angles and angular velocity would change at each pedaling. Seven male college cyclists were selected, and their pedaling movements were divided into four phases. The images were taped at 60fields/sec, using two video cameras. The KWON 3D 2.1 program was adopted to calculate and synchronize the 3D coordinates values which were calculated with DLT(Direct Liner Transformation), in order to analyze kinematical factors. The results were as follows: 1) There was found no difference between foot joint angles according to changes of knee joint angles in each phase. But it became clear that Phase 1 and 2 where the foot angle got bigger were the area where the foot joint was expanded and that Phase 3 and 4 where the foot angle got smaller were the area where the foot joint was bent. Accordingly, the area which gives a great indirect impact to the changes of foot joint angles is considered to be the first part of Phase 3 at which point the cycle of pedaling starts. 2) In terms of the difference of foot joint angular velocity according to knee joint angles, there was found a relatively stable deceleration in the decelerating area(Phase 3 and 4) while you could detect faster changes in the acceleration area(Phase 1 and 2) than in the decelerating area. 3) The changes in the angle difference of knee joints according to each knee joint angle showed almost similar patterns for every knee joint. But the patterns had the graph model of the opposite shape to that of the angle difference of foot joints. 4) The research went on to see what kind of difference the knee joint angle made as knee joint angular velocity changed. The changes were unlike the foot joint angular velocity and thus showed relatively slow deceleration and acceleration. And the higher the saddle was set, the bigger the difference of the angular velocity was. 5) The difference of hip joint angles according to knee joint angles made a graph pattern which showed no big correlation with the height of a saddle. 6) In considering how hip joint angular velocity would change according to knee joint angles, the higher a saddle was set, the bigger angular velocity was found in Phase 1 and 2, the area of joint expansion and the smaller angular velocity in Phase 3 and 4, the area of joint bending. Comparisons and analysis were made based on the results above mentioned. The conclusion was that the lower a saddle which was one of the three experiment conditions was set, the smoother the pedaling turned and the bigger the angular velocity was resulted. In other words, when you take a long road cycling with your saddle fixed at a little lower height than the average one, you will consume less physical strength and expect better performance.

아세틸 콜린 유발 검사시 허혈성 심전도 변화와 흉통의 발생이 내피세포 기능장애에 미치는 영향

최철웅(Cheol Ung Choi),나승운(Seung-Woon Rha),김선원(Sun Won Kim),나진오(Jin Oh Na),임홍의(Hong Euy Lim),김진원(Jin Won Kim),김응주(Eung Ju Kim),한성우(Seong Woo Han),박창규(Chang Gyu Park),서홍석(Hong Seog Seo),오동주(Dong Joo Oh) 대한임상노인의학회 2010 대한임상노인의학회지 Vol.11 No.4

연구배경: 아세틸 콜린 유발 검사시 발생하는 흉통과 허혈성 심전도 변화가 아세틸 콜린에 의해 발생하는 관상동맥의 내피세포 기능에 어떤 영향을 주는지 알아보고자 했다. 방법: 흉통으로 내원하여 관상동맥 조영술과 아세틸 콜린 유발검사를 시행받은 1,085명의 환자를 대상으로 하였다. 아세틸 콜린 유발 검사를 하는 동안 허혈성 심전도 변화 및 흉통의 발생 유무에 따른 관상동맥 내피세포 기능의 특징을 비교하였다. 결과: 539명의 환자에서 아세틸 콜린 검사시 내피세포 기능 장애가 발생 하였다. 허혈성 심전도 변화가 있었던 그룹이 심전도 변화가 없었던 그룹보다 흉통이 더 많았고(78.1% vs. 60.8%, P=0.007), 관상동맥 조영술상 다발성 관상동맥 경련이 빈번하였고(59.4% vs. 40.6%, P=0.004), 관상동맥의 경련 정도도 더 심하였다(64.1% vs. 46.5%, P=0.006). 흉통이 있었던 그룹이 흉통이 없었던 그룹보다 허혈성 심전도 변화의 빈도가 더 높았다(14.7% vs. 7.5%, P=0.007). 또한 흉통이 있었던 그룹이 관상동맥 경련이 다발성으로 발생하는 경우가 많았고 (50.7% vs. 29.5%, P<0.001), 미만성으로 발생하는 경우가 많았고(87.1% vs. 75%, P<0.001), 관상동맥의 경련의 정도도 더 심하였다(51.6% vs. 43.5%, P=0.041). 결론: 아세틸 콜린 유발검사시 발생하는 허혈성 심전도 변화와 흉통은 관상동맥 경련의 정도와 경련이 발생하는 관상동맥 개수와 연관이 있다. Background: ECG changes and chest pain during acetylcholine (Ach) provocation tests may constitute important clinical parameters for Ach-induced endothelial dysfunction. We investigated the association between ischemic ECG changes and chest pain during the Ach-provocation test and angiographic characteristics of Ach-induced endothelial dysfunction. Methods: A total of 1,085 patients with anginal symptoms underwent diagnostic coronary angiography (CAG) and Ach-provocation tests. We compared angiographic characteristics of Ach-induced endothelial dysfunction according to the presence of ECG change and chest pain. Results: A total of 539 patients experienced Ach-induced endothelial dysfunction. Patients who experienced ECG change group suffered more frequent chest pain (78.1% vs. 60.8%, P=0.007), angiographically more frequent multiple coronary artery spasm (59.4% vs. 40.6%, P=0.004), and more severe coronary artery spasm (64.1% vs. 46.5%, P=0.006) than patients without ECG change. However, there was no difference in the length of endothelial dysfunction between the groups. The incidence of ischemic ECG changes in patients with chest pain was higher than in patients without chest pain (14.7% vs. 7.5%, P=0.007). Patients who experienced chest pain more often experienced multiple (50.7% vs. 29.5%, P<0.001), diffuse (87.1% vs. 75%, P<0.001), and severe coronary artery spasm (51.6% vs. 43.5%, P=0.041) than patients without chest pain. Conclusion: Ischemic ECG changes and chest pain during the Ach-provocation test are associated with multi-vessel involvement and severe coronary artery spasm. Chest pain is associated with the length of endothelial dysfunction, but ischemic ECG change is not.

Projections of summertime ozone concentration over East Asia under multiple IPCC SRES emission scenarios

Lee, Jae-Bum,Cha, Jun-Seok,Hong, Sung-Chul,Choi, Jin-Young,Myoung, Ji-Su,Park, Rokjin J.,Woo, Jung-Hun,Ho, Changhoi,Han, Jin-Seok,Song, Chang-Keun Elsevier 2015 Atmospheric environment Vol.106 No.-

<P><B>Abstract</B></P> <P>We have developed the Integrated Climate and Air Quality Modeling System (ICAMS) through the one-way nesting of global–regional models to examine the changes in the surface ozone concentrations over East Asia under future climate scenarios. Model simulations have been conducted for the present period of 1996–2005 to evaluate the performance of ICAMS. The simulated surface ozone concentrations reproduced the observed monthly mean concentrations at sites in East Asia with high R<SUP>2</SUP> values (0.4–0.9), indicating a successful simulation to capture both spatial and temporal variability. We then performed several model simulations with the six IPCC SRES scenarios (A2, A1B, A1FI, A1T, B1, and B2) for the next three periods, 2016–2025 (the 2020s), 2046–2055 (the 2050s), and 2091–2100 (the 2090s). The model results show that the projected changes of the annual daily mean maximum eight-hour (DM8H) surface ozone concentrations in summertime for East Asia are in the range of 2–8 ppb, −3 to 8 ppb, and −7 to 9 ppb for the 2020s, the 2050s, and the 2090s, respectively, and are primarily determined based on the emission changes of NO<SUB>x</SUB> and NMVOC. The maximum increases in the annual DM8H surface ozone and high-ozone events occur in the 2020s for all scenarios except for A2, implying that the air quality over East Asia is likely to get worse in the near future period (the 2020s) than in the far future periods (the 2050s and the 2090s). The changes in the future environment based on IPCC SRES scenarios would also influence the change in the occurrences of high-concentrations events more greatly than that of the annual DM8H surface ozone concentrations. Sensitivity simulations show that the emissions increase is the key factor in determining future regional surface ozone concentrations in the case of a developing country, China, whereas a developed country, Japan would be influenced more greatly by effects of the regional climate change than the increase in emissions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Change in ozone level is determined by the combination of NO<SUB>x</SUB> and NMVOC emissions. </LI> <LI> Ozone level over East Asia would get worse in the near future (the 2020s) than far future. </LI> <LI> A high-concentration event generally increases and more frequently occurs in the future. </LI> <LI> Change in ozone air quality in a developing country depends more on emissions change. </LI> <LI> Change in ozone air quality in a developed country depends more on climate change. </LI> </UL> </P>

Changes of Sugar Composition and Related Enzyme Activities during Fruit Development of Asian Pear Cultivars ‘Niitaka’ and ‘Whangkeumbae’

Jin-Ho Choi,Jang-Jeon Choi,Chang-Seok Bang,Jung-Sup Lee,Dong-Woog Choi,Hye-Sun Cho,Jun Cheul Ahn 한국원예학회 2009 Horticulture, Environment, and Biotechnology Vol.50 No.6

We report on the seasonal changes of soluble sugar accumulation and several enzyme activities related to sugar metabolism, in two Asian pear cultivars (Pyrus pyrifolia) cultivars ‘Niitaka’ and ‘Whangkeumbae’. Soluble sugar content increased as the fruit developed and its total contents in matured fruits were 104.6 and 95.1 ㎎ㆍg?¹ fresh weight for ‘Niitaka’ and ‘Whangkeumbae’, respectively. However, the fructose-glucose-sucrose-sorbitol ratio was not significantly changed. Sorbitol-6-phosphate dehydrogenase activity was maintained at high level in leaves and low in fruits throughout the fruit development, although the enzyme activity highly fluctuated in young and mature fruits. NAD-dependent sorbitol dehydrogenase activity increased sigmoidally in both leaves and fruits during fruit development, and correlated with accumulation of total sugar in fruits. Sucrose synthase and sucrose phosphate synthase (SPS) activities remained low in leaves, but higher with two peak fluctuations in fruits. The change of soluble sugar contents positively correlated with SPS activity, based on the seasonal fluctuation of SPS activity and soluble sugar accumulation.

조혈모세포이식 환자에서 발생한 Cytomegalovirus 질환의 특징 : 일개 대학변원에서 최근 10년간의 경험

최수미,이동건,박선희,김시현,김유진,민창기,김희제,이석,최정현,유진홍,김동욱,이종욱,민우성,신완식,김춘추 대한감염학회 2009 감염과 화학요법 Vol.41 No.1

Background : Studies on cytomegalovirus (CMV) diseases in Korean hematopoietic stem cell transplant (HSCT) recipients are lacking and do not reflect the recent trends of advances and changes. Therefore, we tried to analyze the clinical features of CMV diseases in HSCT recipients over the past 10 years at a tertiary university hospital in Korea. Methods : Retrospective review of medical records was done for all adult HSCT patients who received transplant at the Catholic HSCT Center from January 1998 to January 2008. Results : Forty-four cases (2.2%) of CMV diseases were identified. CMV pneumonia was diagnosed in 17 patients, retinitis in 16 patients, enterocolitis in 7 patients, esophagitis 1 patient, gastritis in 1 patient, duodenitis in 1 patient, and hepatitis in 1 patient. The median onset of symptom was 90 days after transplantation. Late CMV diseases accounted for 47.7%. CMV related death varied from 0 to 58.8% according to the involved organ. CMV retinitis was diagnosed relatively later in the course of transplantation mostly in patients who had chronic graft versus host disease (GVHD). On the contrary, CMV enterocolitis mainly occurred in patients who suffered from acute GVHD. The overall concurrent CMV reactivation was documented to be 63.6%: the concurrent CMV reactivation was observed only in 37.5% of patients with retinitis. Conclusions : We observed some differences in the pattern of CMV disease manifestation according to the involved organ and reconfirmed the fact that CMV pneumonia is the most common and fatal disease in HSCT recipients. Additionally, CMV retinitis was not uncommon in HSCT recipients. Since specific marker does not exist in predicting retinitis, regular ocular examination should be done thoroughly, especially in patients with chronic GVHD.

Kainic Acid에 의한 흰쥐 해마 신경원 가지돌기의 독성변화에 대한 광학 및 전자현미경 연구

최진영,김경용,이원복,김동창 대한해부학회 1993 Anatomy & Cell Biology Vol.26 No.4

Investigation of high contrast and reversible luminescence thermochromism of the quantum confined Cs₄PbBr₆ perovskite solid

Choi, Jin Woo,Cho, Namchul,Woo, Hee Chul,Oh, Byeong M.,Almutlaq, Jawaher,Bakr, Osman M.,Kim, Sung-Hoon,Lee, Chang-Lyoul,Kim, Jong H. The Royal Society of Chemistry 2019 Nanoscale Vol.11 No.12

<P>Thermochromism of organic/inorganic halide perovskites has attracted particular interest due to their potential applications as photoluminescence (PL)-based temperature sensors. However, despite the outstanding PL characteristics, their use as a thermochromic material in practical temperature ranges has been limited because of their poor thermal stability. In this study, we used the quantum confinement effect and exceptional PL quantum efficiency of the Cs4PbBr6 perovskite to demonstrate their high on/off ratio (20) and reversible PL thermochromism in the solid state in practical temperature ranges including room temperature (RT). Systematic photophysical and optical characterization studies, including exciton-phonon scattering, exciton binding energy, exciton decay dynamics, and crystal structure change, were performed to investigate the origin of this unique thermochromic PL property. The results showed that the efficient and highly reversible thermochromic PL emission of the Cs4PbBr6 perovskite is due to its desirable optical properties such as highly luminescent emission, efficient PL quenching at high temperatures, and thermally reversible structural changes.</P>

Sphingosine 1-Phosphate and Sphingosine Kinase Activity during Chicken Embryonic Development

Choi, Chang-Hwan,Jeong, Ji-Seon,Yoo, Bo-Im,Jin, You-Xun,Moon, Dong-Cheul,Yoo, Hwan-Soo,Oh, Seik-Wan,Hong, Seon-Pyo,Lee, Yong-Moon 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.4

The chicken embryo has been weil used in studies of the developmental process, and during development sphingosine and sphingosine 1-phosphate (So1P) are considered critical mediators of cell death and survival. In this study, we compared the sphingolipid contents of chicken embryos during the early embryonic development period from day 3 to day 6. HPLC analyses of sphingosine and So1P in chicken embryos revealed that sphingosine levels were greatly reduced on day 4 whereas So1P levels were not significantly changed. Sphingosine kinase(Sphk) activities, which require sphingosine as substrate to produce So1P, were also greatly reduced on day 4. Collectively, we found sphingosine levels and Sphk activities, but not So1P levels are changed in early stage of chicken embryos development.

Sphingosine 1-Phosphate and Sphingosine Kinase Activity during Chicken Embryonic Development

Chang-Hwan Choi,정지선,Bo-im Yoo,You-Xun Jin,문동철,유환수,오세관,홍선표,이용문 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.4

The chicken embryo has been well used in studies of the developmental process, and during development sphingosine and sphingosine 1-phosphate (So1P) are considered critical mediators of cell death and survival. In this study, we compared the sphingolipid contents of chicken embryos during the early embryonic development period from day 3 to day 6. HPLC analyses of sphingosine and So1P in chicken embryos revealed that sphingosine levels were greatly reduced on day 4 whereas So1P levels were not significantly changed. Sphingosine kinase (Sphk) activities, which require sphingosine as substrate to produce So1P, were also greatly reduced on day 4. Collectively, we found sphingosine levels and Sphk activities, but not So1P levels are changed in early stage of chicken embryos development.

A two-photon ratiometric probe for hydrogen polysulfide (H₂S_n): Increase in mitochondrial H₂S_n production in a Parkinson’s disease model

Choi, Hyeon Jin,Lim, Chang Su,Cho, Myoung Ki,Kang, Ji Su,Park, Soo Jin,Park, Sang Myun,Kim, Hwan Myung Elsevier 2019 Sensors and actuators. B, Chemical Vol.283 No.-

<P><B>Abstract</B></P> <P>Hydrogen polysulfide (H<SUB>2</SUB>S<SUB>n</SUB>, n>1), which is primarily generated during the crosstalk between H<SUB>2</SUB>S and reactive species (ROS and RNS), is receiving increasing attention in biochemical research. H<SUB>2</SUB>S<SUB>n</SUB> is mostly generated in the mitochondria, and abnormal mitochondrial function and oxidative stress are directly related to many disorders including Parkinson's disease (PD). We now report a two-photon fluorescent probe (<B>SPS-M1</B>) for in situ detection of H<SUB>2</SUB>S<SUB>n</SUB> and its application to a PD model to account the H<SUB>2</SUB>S<SUB>n</SUB> levels. The probe exhibited selective and fast response to H<SUB>2</SUB>S<SUB>n</SUB> along with a marked blue-to-green color change. <B>SPS-M1</B> is sensitive enough to quantitative detection of endogenous H<SUB>2</SUB>S<SUB>n</SUB> content in mitochondria using two-photon microscopy (TPM). Ratiometric TPM imaging of live neurons and brain slices using <B>SPS-M1</B> revealed that H<SUB>2</SUB>S<SUB>n</SUB> production is increased to a greater extent in the A53 T α-synuclein (α-syn) overexpressing model than in the wild-type control. These findings suggest that the interactions of H<SUB>2</SUB>S and the increased ROS caused by α-syn overexpression may generate more H<SUB>2</SUB>S<SUB>n</SUB>. By employing our recently published TP probe for mitochondrial H<SUB>2</SUB>S, we also found the relationship between the H<SUB>2</SUB>S<SUB>n</SUB> and H<SUB>2</SUB>S; increased H<SUB>2</SUB>S<SUB>n</SUB> and decreased H<SUB>2</SUB>S levels, indicating that H<SUB>2</SUB>S and H<SUB>2</SUB>S<SUB>n</SUB> may play a significant role in the pathogenesis of PD. This result may be useful to biomedical studies, including PD.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A two-photon excitable and emission ratiometric probe for hydrogen polysulfide (H<SUB>2</SUB>S<SUB>n</SUB>) in mitochondria was developed. </LI> <LI> The probe is able to direct visualization of the endogenous H<SUB>2</SUB>S<SUB>n</SUB> level using two-photon microscopy (TPM). </LI> <LI> Ratiometric TPM imaging revealed that H<SUB>2</SUB>S<SUB>n</SUB> production is increased in a Parkinson’s Disease model. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>