키토산이 백서 태자 두개관세포에 미치는 영향

김정경,정현주,김영준,김옥수,Kim, Jeong-Kyung,Chung, Hyun-Ju,Kim, Young-Joon,Kim, Ok-Su 대한치주과학회 2004 Journal of Periodontal & Implant Science Vol.34 No.4

The effect of chitosan, a carbohydrate biopolymer extracted from chitin, on periodontal regeneration is of particular interest. The purpose of this study was to evaluate the effect of chitosan on primary rat calvarial cells in vitro, with special focus on their proliferative properties by cell activity and the amount of total protein synthesis. The experimental groups were cultured with chitosan in concentration of 0.01, 0.1, 1.0, 2.0 and 5.0 mg/ml for MTT assay. In the experimental groups, cells were cultured with chitosan in concentration of 0.01, 0.1, 1.0 and 2.0 mg/ml. Each group was characterized by examining alkaline phosphatase activity at 3 and 7 days and the ability to produce mineralized nodules of rat calvarial cells at 14 and 21 days. The results were as follows: 1. The cell activity was not reduced in the concentration of $0.01{\sim}1.0$ mg/ml whereas the cell activity was reduced in the concentration of 5.0 mg/ml than the control at day 1 and 3 (p<0.05). 2. Primary rat calvarial cells treated with chitosan in the concentration 0.01 mg/ml and 0.1 mg/ml showed more protein synthesis than the control at day 3 (p<0.01), But primary rat calvarial cells treated with chitosan showed more protein synthesis than in control but they didn't have statistically difference among groups at day 7. 3. At 3 and 7 days, alkaline phosphatase activity was significantly increased in the concentration of 0.01 mg/ml. 0.1 mg/ml and 1.0 mg/ml (p<0.05). 4. The percentage of mineralized bone nodule was more in the concentration of chitosan 0.1 mg/ml and 1.0 mg/ml than the control. These results suggested that chitosan has a positive effect on the bone formation of primary rat calvarial cells in the concentration of 0.1 mg/ml and 1.0 mg/ml.

나트륨-물 반응에 의한 전열관 표면에서의 부식과 반응특성에 대한 연구

정경채 ( Kyung Chai Jeong ),정지영 ( Ji Yong Jeong ),김병호 ( Byung Ho Kim ),김태준 ( Tae Joon Kim ),최종현 ( Jong Hyeun Choi ),김의식 ( Eui Sik Kim ) 한국공업화학회 2003 공업화학 Vol.14 No.1

본 연구에서는 증기발생기 전열관 재질로 예상되는 페라이트 강을 사용해서, 액체 나트륨 분위기에서 미량 물누출 실험을 수행하여, 시편의 누출 부위와 표적표면에서 발생되는 재질의 부식현상. 나트륨-물 반응에 의한 온도 상승현상 등에 대한 특성을 관찰하였다. 실험결과, 시편의 누출구멍 주변은 나트륨부위에서 나트륨-물 반응에 의해 발생되는 부식 및 침식에 의한 wastage 현상에 의해 손상을 입어 누출 구멍의 직경이 확대되었으며, 누출 부위에서의 손상은 초기 누출구멍 크기인 150㎛에서 200㎛정도로 확대되었고, 표적표면에 나타난 손상부위의 크기는 약 1000㎛ 정도로 분석되었다. 또한, 표적표면에서의 온도는 나트륨-물 반응에 의해 형성되는 반응열에 의해 약 70-80℃ 정도 상승하였으며, 손상부위 표명을 EPMA 및 EDX로 분석한 결과, 나트륨 산화물과 전열관의 모지 금속을 구성하는 Fe이나 Cr 등의 원소와 반응하여 (NaOH+Na_2O)ㆍFe_xO_y나 (NaCrO_2+Na_2Cro_4) 같은 형태의 복합산화물을 형성하는 것으로 판명되었다. In this study we observed and analyzed the corrosion phenomena in a leak site and he effect of temperature at the target surface of heat transfer tube material by sodium-water reaction through water leakage in liquid sodium atmosphere. Surrounding of the leak hole of the specimen was damaged by the wastage phenomena due to corrosion and erosion of material, and the hole size, by damage of leak site, was extended from 150㎛to about 200㎛. Also, the damaged size appeared in the target surface was observed to be about 1000㎛ diameter. The temperature of target surface increased about 70~80℃ by the heat of sodium-water reaction even with a small leakage of 15mL water. From the results of EPMA and EDX analysis, damaged areas are found to be covered with complex compounds such as (NaOH+Na_2O)·Fe_xO_y or (NaCrO_2+Na_2CrO_4) mixed up with the sodium oxides by sodium-water reaction and the Fe or Cr element by matrix of tube material.

중도탈락 후보 지지층과 응답유보층 보정을 통한 선거결과 예측

김정경 ( Jeong-kyung Kim ),박민규 ( Mingue Park ) 한국조사연구학회 2023 조사연구 Vol.24 No.2

본 연구에서는 NBS 선거여론조사 결과를 활용하여 2022년 3월에 실시한 20대 대통령선거의 당선자를 예측하는 통계적 방안을 살펴보았다. 20대 대통령선거의 경우 투표일 1주일 전까지 지지 gnqh자를 결정하지 못한 응답유보자가 약 20%에 달하였으며, 선거일 직전에 안철수 후보의 사퇴가 있었던 점을 고려하여 응답유보자와 안철수 후보 지지자를 지도학습 방법을 통해 분류한 후각 후보의 득표율을 예측하였다. 지도학습 도구로는 로지스틱 회귀분석, 의사결정나무 그리고 랜덤포레스트 방안을 고려하였다. 득표율의 예측에 있어서는 랜덤포레스트 방안이 가장 좋은 성능을 보였으며, 모든 방안이 1, 2위 후보자 득표율의 비율을 유사하게 예측하였다. 선거일에 가까울수록 예측의 정확도는 대체로 높아졌으나, 응답률이 상대적으로 낮았던 시점의 예측오차는 매우 크게 나타났다. 여론조사 공표보도 금지기간이 해제되어 투표일 직전 자료를 활용한 응답유보자 분류가 가능하다면 선거여론조사를 활용한 득표율 예측은 더욱 정교해질 것으로 기대된다. This study examines a statistical plan to predict the winners of the 20th presidential election held in March 2022 using the results of the NBS election poll. About 20% of respondents in the 20th presidential election could not decide their supporters until a week before the voting date. Considering that Ahn Cheol Soo resigned just before the election day, the percentage of votes for each candidate was predicted after classifying them through supervised learning. The supervised learning tools considered were logistic regression analysis, decision tree, and random forest measures. The Random Forest method showed the best performance in predicting the vote rate, and all measures similarly predicted the ratio of the vote rate of the first and second candidates. The accuracy of the prediction increased as the election date approached, but the prediction error at the time when the response rate was relatively low was very large. If the prohibition period for reporting public opinion polls is lifted and thus it is possible to classify respondents using data just before the voting day, the prediction of the vote rate using election polls is expected to be more sophisticated.

고온가스로용 핵연료 중간화합물 제조에 대한 연구

김연구,서동수,정경채,오승철,조문성,Kim, Yeon-Ku,Suhr, Dong-Soo,Jeong, Kyung-Chai,Oh, Seung-Chul,Cho, Moon-Sung 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.11

In this study the preparation method of the spherical ADU droplets, intermediate compound of a HTGR nuclear fuel, was detailed-reviewed and then, the characteristics on an ageing and a washing steps among the wet process and the thermal treatment process on the died-ADU${\rightarrow}UO_3$ conversion with the high temperature furnaces were studied. The key parameters for spherical droplets forming are a precise control of feed rate and a suitable viscosity value selection of a broth solution. Also, a harmony of vibrating frequency and amplitude of a vibration dropping system are important factor. In our case, an uranium concentration is $0.5{\sim}0.7mol/l$, viscosity is $50{\sim}80$ centi-Poise, vibration frequency is about 100Hz. In thermal treatment for no crack spherical $UO_3$ particle, the heating rate in the calcination must be operated below $2^{\circ}C$/min, in air atmosphere.

고온가스로용 핵연료 UO₂ Kernel 입자제조

정경채,김연구,오승철,조문성,Jeong, Kyung-Chai,Kim, Yeon-Ku,Oh, Seung-Chul,Cho, Moon-Sung 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.8

The broth solution was prepared by the mixing of an uranyl nitrate, THFA, PVA, and water. The uranium concentration of the broth solution was $0.5{\sim}0.8$ mole-U/L and the viscosity of it was $30{\sim}80cSt$. The droplets of this broth solution were farmed in air and ammonia by the vibrating nozzle with the frequency of 100 Hz at the amplitude of $100{\sim}130V$. The diameter of the droplet was about $1900{\mu}m$ from using the nozzle diameter of 1 mm. The diameter of the aged gel was about $1400{\mu}m$ after aging in ammonia solution at $60{\sim}80^{\circ}C$, and the dried gel with the diameter of about $900{\mu}m$ was obtained after drying at room temperature or partially vacuum condition. The diameter of the calcined $UO_3$ microsphere after calcination at $600^{\circ}C$ appeared about $800{\mu}m$ in air atmosphere. Although the droplets of the same sizes were formed, the calcined microspheres of different sizes were manufactured in the case of the broth solutions of the different uranium concentration. The droplets of the desired diameters were obtained by the change of the nozzle diameters and the broth flow rates.

Le Fort 3 골절단술: 문헌고찰

정경인 ( Kyung In Jeong ),문철웅 ( Chul Ung Moon ),김수관 ( Su Gwan Kim ),문성용 ( Seong Yong Moon ),오지수 ( Ji Su Oh ) 조선대학교 구강생물학연구소 2011 Oral Biology Research (Oral Biol Res) Vol.35 No.2

Patients who has craniofacial dysplasia and syndrome usually shows mid-facial hypoplasia. Reconstruction by Le Fort III osteotomy is most recommended for esthetic reconstruction of the face, improvement of occlusion and expansion of narrowed airway. Although there are various modifications of osteotomy, the most important thing is selection of the method for fixation after bone movement or distraction osteogenesis at each patient, in which age and growth of patients and stability after surgery must be considered. In this study, indication, proper time and surgical method of Le Fort III osteotomy were reviewed. Le Fort III osteotomy is the excellent surgical technique in which the relapse is low in the midfacial deformity patients although risk of the surgery is high.

변형 Sol-Gel 방법을 이용한 고온가스로 핵연료 미세구입자 제조

정경채,김연구,오승철,조문성,Jeong, Kyung-Chai,Kim, Yeon-Ku,Oh, Seung-Chul,Cho, Moon-Sung 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6

$UO_2$ microsphere particles, core material of HTGR(High Temperature Gas Reactor) nuclear fuel, were prepared using by the GSP(Gel Supported Precipitation) method which is a modified-method of the wet sol-gel process. The spherical shape of initial liquid ADU droplets from the vibration nozzle system was continuously kept till the conversion to the final $UO_2$ microsphere. But the size of a final $UO_2$ microsphere was shrunken to about 25% of an initial ADU droplet size. Also, we found that the composition of dried-ADU gel particles was constituted of the very complicated phases, coexisted the U=O, C-H, N-H, N-O, and O-H functional groups by FT-IR. The important factors for obtain the no-crack $UO_2$ microsphere during the thermal treatment processes must perfectly wash out the remained-$NH_4NO_3$ within the ADU gel particle in washing process and the selections of an appropriate heating rate at a suitable gas atmosphere, during the calcining of ADU gel particles, the reducing of $UO_3$ particles, and the sintering of $UO_2$ particles, respectively.

고온가스로용 핵연료 제조에서 열처리 조건이 우라늄산화물 입자 특성에 미치는 영향

김연구,정경채,오승철,서동수,조문성,Kim, Yeon-Ku,Jeong, Kyung-Chai,Oh, Seung-Chul,Suhr, Dong-Soo,Cho, Moon-Sung 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.2

The effects of thermal treatment conditions on ADU (ammonium diuranate) prepared by SOL-GEL method, so-called GSP (Gel supported precipitation) process, were investigated for $UO_2$ kernel preparation. In this study, ADU compound particles were calcined to $UO_3$ particles in air and Ar atmospheres, and these $UO_3$ particles were reduced and sintered in 4%-$H_2$/Ar. During the thermal calcining treatment in air, ADU compound was slightly decomposed, and then converted to $UO_3$ phases at $500^{\circ}C$. At $600^{\circ}C$, the $U_3O_8$ phase appeared together with $UO_3$. After sintering of theses particles, the uranium oxide phases were reduced to a stoichiometric $UO_2$. As a result of the calcining treatment in Ar, more reduced-form of uranium oxide was observed than that treated in air atmosphere by XRD analysis. The final phases of these particles were estimated as a mixture of $U_3O_7$ and $U_4O_9$.

Sol-gel 공정을 이용한 UO₂ kernel 제조에서 공정변수가 입자특성에 미치는 영향

김연구,정경채,오승철,서동수,조문성,Kim, Yeon-Ku,Jeong, Kyung-Chai,Oh, Seung-Chul,Suhr, Dong-Soo,Cho, Moon-Sung 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.4

In this study, we investigated the unit process parameters in spherical $UO_2$ kernel preparation. Nearly perfect spherical $UO_3$ microspheres were obtained from the 0.6M of U-concentration in the broth solution, and the microstructure of the $UO_2$ kernel appeared the good results in the calcining, reducing, and sintering processes. For good sphericity, high density, suitable microstructure, and no-crack final $UO_2$ microspheres, the temperature control range in calcination process was $300{\sim}450^{\circ}C$, and the microstructure, the pore structure, and the density of $UO_2$ kernel could be controlled in this temperature range. Also, the concentration changes of the ageing solution in aging step were not effective factor in the gelation of the liquid droplets, but the temperature change of the ageing solution was very sensitive for the final ADU gel particles.

선택적 UV필터를 이용한 전력기기고장 예측용 코로나방전 진단시스템 개발

정경열(Kyung-yul Chung),박창대(Chang-dae Park),임병주(Byung-ju Lim),한정은(Jeong-eun Han),김권태(Kwun-tae Kim),최대석(Dae-seok Choi),심상용(Sang-yong Sim),김용환(Yong-hwan Kim),김용식(Yong-sik Kim) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.10

In this paper, we propose electric corona discharge diagnosis system based on the selective UV optics to find discharging location and the electric facility degradation. And we have verify the system by lab tests and field tests and present the results.