에코콘크리트의 독성시험

宋昌燮,李信昊,金明煥 忠北大學校 農業科學硏究所 2003 農業科學硏究 Vol.20 No.-

This study was performed to analyze the toxic effects fo ecoconcrete which was developed to be applicate the farm road and agricultural structure's backfill materials To this ends, a series of test was conducted for the soil picked in Hagso, located in Chungbuk province The mixture ratio of ESC was 10%, 20% and 30% by weight of dry soil Produced sample was observed through state of fish by intervals of time From the first toxic test result, singularity symptoms were observed to fish increases with ESC mixture ratio Common symptoms were observed impaired digestion, difficulty in breathing, body color change Specially, singularity symptoms were observed the most notedly in aquarium which mixture ratio 20% After 18 days the second toxic test result, it was found that in number of survival of fish could not observed change in aquarium, excepted ESC mixture ratio 20% Therefore, developed ecoconcrete does not influenced in number of survival of fish

HELLP증후군의 임상양상과 예후에 관한 연구

이창환,손성경,이석수,이윤이 충남대학교 의과대학 지역사회의학연구소 1999 충남의대잡지 Vol.26 No.2

The syndrome of hemolysis, elevated liver enzymes and low platelet count during pregnancy (HELLP syndrome) is recognized as a serous, multisystemic disease and associated with poor maternal and perinatal outcome. The purpose of this study is to elevate the clinical appearance and the maternal and perinatal outcome with HELLP syndrome. It was a retrospective study that maternal outcome and perinatal variables and the clinical course of eight cases HELLP syndrome in 234 cases with pregnancy induced hypertension who visited the Department of Obstetrics and Gynecology, Chungnam National University Hospital from January 1995 to December 1998. The results were as follows; 1. The incidence of the HELLP syndrome among patient with pregnancy induced hypertension was 3.4%(8/234) and mean age, mean gestational age was each 29.7 year-old, 36.7 weeks and there was 3 primigravidas and 5 multipara(38% vs 62%). 2. In the abnormal elevated laboratory finding on admission, mean platelet count, sGOT, sGPT, total bilirubin, LDH, BUN, and creatinine was each as 74,000/㎣, 2231U/ℓ, 1941U/ℓ, 1.7mg/㎗, 10951U/ℓ, 22.3mg/㎗ and 2.0mg/㎗. 3. About the coagulation system, PT and aPTT were all within the normal limit but in 38% of patient with HELLP syndrome fibrinogen was decreased, in 50% FDP was increased and in 25% patient was made diagnosis of DIC. 4. The 6 cases were perceived as immediate delivery, one case was vaginal delivery only and others cesarean section and maternal complication was placenta abruption, severe pulmonary edema, acute renal insufficiency, acute toxic hepatitis and cardiomyopathy but there was no maternal mortality in all cases. 5. The mean birth weight 2,374g, 50% of fetus were delivered before 38 weeks, the IUGR was found in 25% and the perinatal mortality rate was 25%. 6. Neonatal complication was neonatal asphyxia, RDS(> 2 grade), sepsis, hyperbilirubinemia, hypermagnesemia, TTN and major handicaps of PVL. These findings suggest that infants born to HELLP syndrome mother have an increased need for resuscitation at delivery and aggressive management for mothers. Thus obstetricians should be identified promptly and need for appropriate management of nowborn infant and mothers with HELLP syndrome.

산화툴륨의 결함구조와 전기전도성에 대한 연구

최재시,정원양,김진호,이창환 연세대학교 자연과학연구소 1985 學術論文集 Vol.14 No.-

산화툴륨의 전기전도도를 400~1100℃의 온도영역과 10^-6~10^-1atm의 산소분압범위에서 측정하였다. 일정한 산소분압에서 전기전도도의 대수값을 절대온도의 역수에 대하여 도시한결과 직선관계를 얻었으며 inflection point가 나타났다. 활성화에너지는 고온영역에서 34.5kcal/mole, 저온영역에서 19.3kcal/mole이었다. 전기전도도의 산소분압의존성은 직선관계를 나타내었으며 600~1100℃의 온도영역에서 σ∝Po_2^1/5.3, 400~600℃의 온도영역에서σ∝Po_2^1/6.3이었다. 고온영역에서의 주결함은 V_??이며, 저온영역에서는 O_?? 임이 밝혀졌다. 전도도의 온도 및 산소분압의존성을 해석하였으며, 전도메카니즘을 제시하였다. The electrical conductivity of thulium sesquioxide has been measured from 400 to 1100℃ under oxygen partial pressure (Po_2) of 10^-6 to 10^-1 atm. Plots of log conductivity vs. 1/T at constant Po_2 are found to be linear with inflection point and the activation energies obtained from the slopes are 34.5kcal/mole in the higher temperature region and 19.3kcal/mole in the lower temperature region. The Po_2 dependences of the electrical conductivity are found to be linear and closely approximated by σ∝Po_2^1/5.3 in the temperature range of 600-1100℃ and σ∝Po_2^1/6.3 in the range of 400-600℃. The dominant defect is V_?? in the higher temperature region and O_?? in the lower temperature region. The interpretations of conductivity dependences on temperature and Po_2 are presented and conduction mechanisms are suggested to illustrate the data.

Vitamin C facilitates dopamine neuron differentiation in fetal midbrain through TET1- and JMJD3-dependent epigenetic control manner.

He, Xi-Biao,Kim, Mirang,Kim, Seon-Young,Yi, Sang-Hoon,Rhee, Yong-Hee,Kim, Taeho,Lee, Eun-Hye,Park, Chang-Hwan,Dixit, Shilpy,Harrison, Fiona E,Lee, Sang-Hun AlphaMed Press 2015 Stem Cells Vol.33 No.4

<P>Intracellular Vitamin C (VC) is maintained at high levels in the developing brain by the activity of sodium-dependent VC transporter 2 (Svct2), suggesting specific VC functions in brain development. A role of VC as a cofactor for Fe(II)-2-oxoglutarate-dependent dioxygenases has recently been suggested. We show that VC supplementation in neural stem cell cultures derived from embryonic midbrains greatly enhanced differentiation toward midbrain-type dopamine (mDA) neurons, the neuronal subtype associated with Parkinson's disease. VC induced gain of 5-hydroxymethylcytosine (5hmC) and loss of H3K27m3 in DA phenotype gene promoters, which are catalyzed by Tet1 and Jmjd3, respectively. Consequently, VC enhanced DA phenotype gene transcriptions in the progenitors by Nurr1, a transcription factor critical for mDA neuron development, to be more accessible to the gene promoters. Further mechanism studies including Tet1 and Jmjd3 knockdown/inhibition experiments revealed that both the 5hmC and H3K27m3 changes, specifically in the progenitor cells, are indispensible for the VC-mediated mDA neuron differentiation. We finally show that in Svct2 knockout mouse embryos, mDA neuron formation in the developing midbrain decreased along with the 5hmC/H3k27m3 changes. These findings together indicate an epigenetic role of VC in midbrain DA neuron development. Stem Cells2015;33:1320-1332</P>

MATLAB 연계를 통한 EMTP/ATPDraw의 성능 향상 방안에 관한 연구

김창환(Chang-Hwan Kim),서훈철(Hun-Chul Seo),김규호(Kyu-Ho Kim),김철환(Chul-Hwan Kim),이상봉(Sang-Bong Rhee) 한국조명·전기설비학회 2016 한국조명·전기설비학회 학술대회논문집 Vol.2016 No.5

EMTP를 이용한 빌딩용 직류 배전 시스템

김창환(Chang-Hwan Kim),서훈철(Hun-Chul Seo),김규호(Kyu-Ho Kim),김철환(Chul-Hwan Kim),이상봉(Sang-Bong Rhee) 한국조명·전기설비학회 2014 한국조명·전기설비학회 학술대회논문집 Vol.2014 No.11

Enhancement of Mechanical Property on Sputtered TiN_x Films with Various Deposition Temperatures

Park, Chang-Hwan,Jang, Bu-Seong,Lee, Chang-Hyun,Sohn, Sunyoung,Rhee, Byung-Roh,Kim, Hwa-Min American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.11

<P>The mechanical properties, such as nano-indentation hardness, texture coefficient, and water contact angle of titanium nitride (TiNx) films by rf-magnetron sputtering system have been investigated as a function of various deposition temperatures. The TiNx films grown over 360 degrees C exhibits an intense compressive stress compared with the films grown below 360 degrees C. The orientation of TiNx film was changed toward (111) direction at 360 degrees C due to increased ion bombardment which favors low surface energy at (111) orientation. The increase of substrate temperature increases the mobility of adatoms promoting closed packing structures in near thermodynamic equilibrium conditions. Thus, for high adatom mobility the TiNx films expected to grow along the (111) orientation corresponding to that with the lowest surface free energy. On the other hand, for low adatom mobility the preferred orientation is the (200) in which the highest number of atoms per unit area can be incorporated at low energy sites. The mechanical properties of TiNx films grown at a pure N-2 atmosphere strongly dependent on the Ts. The highest hardness and the smallest friction coefficient of 26 GPa and mu = 0.13, respectively were in a TiNx film deposited at 400 degrees C. This film was found to be accompanied by a water repellent surface.</P>

고장 발생각을 고려한 비대칭 고장전류 저감을 위한 초전도 한류기 동작 방안

김창환(Chang-Hwan Kim),이상봉(Sang-Bong Rhee),김규호(Kyu-Ho Kim),김철환(Chul-Hwan Kim) 대한전기학회 2013 대한전기학회 학술대회 논문집 Vol.2013 No.7

비대칭 고장전류 저감 기능을 갖는 초전도 한류기 동작 방안

김창환(Chang-Hwan Kim),서훈철(Hun-Chul Seo),김규호(Kyu-Ho Kim),김철환(Chul-Hwan Kim),이상봉(Sang-Bong Rhee) 한국조명·전기설비학회 2014 조명·전기설비학회논문지 Vol.28 No.10

When fault currents contain decaying DC offset, the peak value of the fault current in the first cycle of the fault period is higher than the fault current during the steady-state period. To reduce the asymmetric fault current, this paper proposes an operation scheme using the series connection of two hybrid type Superconducting Fault Current Limiters (SFCLs) : an auxiliary SFCL and a main SFCL. The proposed method calculates the fault angle by comparing the zero-crossing time with fault detection time. According to the fault angle calculated, an auxiliary SFCL operates to reduce an asymmetric fault current during half a cycle after fault occurrence. After this process, the fault current is limited by a main SFCL. To confirm the usefulness of the proposed method, case studies using Electro-Magnetic Transients Program (EMTP)/Alternative Transient Program (ATP) Draw are perfomed.

The Influence of Spondylolisthesis Reduction on the Adjacent Lumbar Segment

Park Tae-Hwan,Choi Yunhee,Kim Tae-Shin,Kim Jun-Hoe,Lee Chang-Hyun,Kim Sum,Kim Young Rak,Ko Yong San,Yuh Woon Tak,Rhee John M.,Kim Kyoung-Tae,Chung Chun Kee,Kim Chi-Heon 대한말초신경학회 2023 The Nerve Vol.9 No.2

Objective: Mild to moderate stenosis at the adjacent level sometimes co-occurs with lumbar spondylolisthesis, but whether to include the adjacent level during surgery for the index level is a matter of debate. Spondylolisthesis causes anterior slipping of the vertebra and reduces the segmental angle at the index level, and the adjacent level may compensate for this change through hyperextension to maintain spinal balance. This study investigated the radiological changes and clinical outcomes of adjacent segment stenosis in patients with lumbar spondylolisthesis. Methods: Forty consecutive patients (12 men and 28 women, age 66.6±10.4 years) underwent single-level oblique lumbar interbody fusion for L4-5 or L5-S1 spondylolisthesis. Lumbar central stenosis at the cranial adjacent segment was present in 16 patients (stenosis group) and absent in 24 patients (no-stenosis group). Clinical and radiological parameters were longitudinally compared between the stenosis and no-stenosis groups. Results: Both groups showed similar and significant clinical improvement. The segmental angle at the index level significantly improved in both groups (p<0.05), but the segmental angle at the cranial adjacent segment significantly decreased only in the stenosis group (p<0.05). The spinal canal area at the adjacent level significantly improved only in the stenosis group (p<0.05). Conclusion: Realigned spondylolisthesis may reduce hyperextension of the adjacent segment. If mild lumbar spinal stenosis is present at an adjacent level to spondylolisthesis, it may not be essential to include it in surgery.