상아질 접착에서 collagenase와 esterase가 미세인장결합강도에 미치는 영향

정영정,현홍근,김영재,김정욱,이상훈,김종철,한세현,장기택 대한소아치과학회 2007 大韓小兒齒科學會誌 Vol.34 No.2

상아질-레진 접착강도에 대한 collagenase와 esterase의 영향을 살펴보기 위해, 소구치의 교합면 상아질에 Single Bond 2와 Clearfil SE Bond로 접착을 시행하고 미세 시편을 제작하여 PBS, collagenase 용액, esterase 용액에 4주간 보관한 후 미세인장결합강도를 측정, 비교하여 다음과 같은 결론을 얻었다. 1. 모든 보관 용액에서 Single Bond 2의 미세인장결합강도는 Clearfil SE Bond보다 유의하게 낮았다(p<0.05). 2. Single Bond 2의 미세인장결합강도는 collagenase군이 PBS군, esterase군보다 낮았다(p>0.05). 3. Clearfil SE Bond의 미세인장결합강도는 esterase군이 PBS군에 비해 낮았으나(p>0.05), collagenase군보다는 높았다(p>0.05). Collagenase군은 PBS군에 비해 유의하게 낮은 미세인장결합강도를 보였다(p<0.05). The purpose of this study was to evaluate the effect of collagenase and esterase on the microtensile bond strength (μTBS) in dentin bonding. After resin composites were bonded to occlusal dentin, μTBS specimens were formed and stored in PBS, collagenase, or esterase solution. After 4-week storage, μTBS was determined and, the results were as follows: 1. μTBS values of Single Bond 2 were lower than those of Clearfil SE Bond for all storage medium (p<0.05). 2. In single Bond 2 group, collagenase solution lowered bond strength more than PBS and esterase solution (p>0.05). 3. In Clearfil SE Bond group, esterase solution lowered bond strength more than PBS(p>0.05). Collagenase solution lowered bond strength more than esterase solution(p>0.05) and PBS(p<0.05).

심실 중격 결손에 의한 감염성 심내막염 환자의 치과치료

양정현,현홍근,김영재,김정욱,장기택,이상훈,한세현,김종철 대한소아치과학회 2007 大韓小兒齒科學會誌 Vol.34 No.3

농촌지역 노인들의 우울증상에 관련된 요인들의 특성

송미숙,전기홍,송현종,김정은,박승구,신상건,이동훈,정성현,최연주,최완철,최민규,황재철,홍지만 아주대학교 1997 아주의학 Vol.2 No.2

This study was performed to identify risk factors for depression among the elderly in a rural area. A survey was done for the elderly living in Gosam-myenn, Ansung-kun during the period of July 28, 1997 and July 30, 1997. Demographic and sodoeconornic characteristics, and functional and health Status were assessed using a structured questionnaire, and the level of depression was measured by GDS score. The data obtained were analyzed by frequencies, percentage, t-test, ANOVA, and multiple regression, and the results were as follows: 1. The total sample consisted of 133 elderly. Of them, 47 elderly (35.4%) showed significant depressive Symptoms. 2. The GDS score was the highest for the group over 85 years of age (p < 0.05). Those living alone or widowed showed lower GDS score than those living with someone or married (p < 0.05). 3. The GDS score was the highest in the absolutely dependent group, followed by the partially dependent group, and the independent group (p < 0.01). The elderly who perceived their health Status as excellent showed the lowest GDS score. In contrast, those who had more than five chronic diseases showed the highest GDS score. 4. The elderly receiving financial and emotional support from their family or friends showed lower GDS score compared to those without any support. 5. The economically dependent group showed higher GDS score than that of independent group. 6. The elderly who involved in leisure activities showed lower GDS score than those without any involvement. 7. In terms of risk factors for depression, we found that perceived health Status, subjective economic Status, leisure activities, living arrangement and financial support were inversely associated with GDS score, whereas labor support was positively associated with GDS score. Based upon the above findings, this study suggests that these risk factors for depression in the elderly should be taken into consideration for a comprehensive mental health program for the elderly living in the rural area.

김치에서 분리한 Lactobacillus sp. JC-7과 Lactobacillus acidophilus 88간의 Electrofusion 최적조건 설정

조영배,최현정,백형석,전홍기 부산대학교 유전공학연구소 1997 분자생물학 연구보 Vol.13 No.-

김치 발효 숙성기간을 연장하고 신선도를 오랫동안 유지 할 수 있는 김치발효 starter의 개발을 목적으로 최적숙성기에 있는 김치로부터 bacteriocin생성능이 없는 유산균을 분리하여 동정하였으며, bacteriocin생성능이 우수한 L.acidophilus 88을 융합시키기 위해 electrofusion에 대한 최적 조건을 검토하였다. 분리균주는 Lactobacillus속으로 동정되어 Lactobacillus sp. JC-7이라 명명하였다. Electrofusion에 의해 생성된 융합주를 식별하기 위해 streptomycin(2.5㎎/ml)에 내성을 나타내는 Lactobacillus sp. JC-7변이주와 kanamycin(600㎍/ml)에 내성을 나타내는 L.acidophilus 88변이주를 분리하였다. Electrofusion을 100V/㎝, 120msec(72ohms,1670 capacitance) 에서 수행했을 때 융합효율이 가장 양호하였으며 전기장의 세기와 시간이 중가할수록 융합 효율이 현저히 감소하였다. 2가 양이온은 농도가 중가할수록 대체적으로 융합효율을 감소시키는 경향을 나타내었으나 1mM MGCl_2에서는 대조군에 비해 융합효율이 약간 증가하였다. PEG매개에 의한 융합법의 융합효율을 비교한 결과, 융합효율은 chemical fusion<electrofusion<electrofusion+20% PEG순을 나타내었다. Evaluation of Optimum Conditions for the Electrofusion between Lactobacillus sp. JC-7 Isolated from Kimchi and Lactobacillus acidophilus 88. Young-Bae Jo, Hyun-Jung Choi, Hyung-Suk Baik and Hong-Ki Jun*. Department of Microbiology, Pusan National University, Pusan 609-735,Korea-A lactic acid bacterium was isolated from kimchi. The isolated strain was identified as the genus Lactobacillus thrugh its morphological characteristics and named as Lactobacillus sp. JC-7. The optimum conditions for the electrofusion between streptomycin(2.5㎎/ml)resistant mutant of Lactobacillus acidophilus 88 and kanamycin(600㎍/ml) resistant mutant Lactobacillus sp. JC-7 were evaluated. The highest number of fusants were obtained at a capacitance value of 120msec(1670㎌), a field strength of 100V/㎝,and a pulse controller setting of 72Ω. The potimum pH of elecroporation buffer was 7.5 and the concentration of divalent cation was 1mM MG^2+. Electrofusants were efficiently obtained by addition 20% polyethylene glycol to electroporation buffer. The yield of fusion was better than that of using polyethylene glycol mediated chemical induction.

법랑질 표면처리방법에 따른 치면열구전색재의 미세누출에 관한 비교연구

현홍근,김정욱,이상훈 대한소아치과학회 2001 大韓小兒齒科學會誌 Vol.28 No.3

최근 air-abrasion기술이 새로운 법랑질 표면처리법으로 소개되고 있는데, 이것이 산부식 처리한 것보다 치면열구전색 전처리에 있어 더 나은 결과를 보이는지 연구할 목적으로.저자들은 표면처리법 및 재료에 따른 미세누출도의 차이를 비교해 보고자 하였다. 9개의 군으로 나눈 시편치아에 산부식(1, 4, 7군). air-abrasion(2. 5, 8군). ail·-abrasion후 산부식(3. 6. 9군) 처리한 후, 3종의 치면열구전색재(1∼3군 : Teethmate-F.4∼6군 Ultraseal XT plus, 7∼9군 : DenSeal)로 전색, 중합하여 색소침투도를 관찰하였으며, 각 시편의 전색재를 분리, 주사전자현미경으로 관찰하여 다음과 같은 결과를 얻었다. 1 표면처리법에 따른 미세누출도는 air-abrasion군, 산부식군 air-abrasion 후 산부식군 순으로 작아졌다(p<0.05) . 단. 7군과 9군간의 유의차는 없었다. 2.미세누출도는 산부식군에서 7군, 4군, 1군, air-abl·asion군에서 8군, 5군, 2군, air-abrasion후 산부식군에서 9군, 3군. 6군 순으로 작아졌으나. 각각 4군과 7군 2군과 5군 3군과 6군간의 유의차는 없었다. 3. SEM상에서, 산부식군은 비교적 긴 레진돌기가 규칙적으로, air-abrasion군은 �裏�레진돌기가 불규칙적으로, air-abrasion후 산부식군에서는 이들이 혼재되어 있는 모습으로 관찰되었다. Recently, the reintroduction of air-abrasion technology in dentistry has added a new potential method of pre-treating teeth prior to placing sealants. The purpose of this in vitro study was to investigate microleakages of several pit and fissure sealants following various surface pre-treatment methods to the enamel , because there was a question concerning the validity of claim that this method was better than the conventional acid etching. Permanent molars were divided randomly into nine groups and treated accordingly: acid etching(group 1, 4, 7), airabrasion(group 2, 5. 8), acid etching after airabrasion(group 3, 6, 9). Then the authors placed and cured the three kinds of sealants(group 1∼3 : Teethmate-F, group 4∼6: Ultraseal XT plus, group 7~9: Denseal) according to the manufacturer's order. They were observed to determine the degree of microleakage . And these specimens were separated from the corresponding enamels and examined by Scanning Electron Microscope. The following results were obtained : 1. In comparing microleakage among tooth surface treatment methods. air-abrasion group (group 2, 5, 8) showed the greatest microleakage. while combination(air-abrasion + acid etching) group showed the least (p<0.05) . However, no significant differences were found between group 7 and 9. 2. The mean microleakages were ranked as follows(p<0.05) : In acid etching groups. group 7> group 4> group 1. In air-abrasive groups. group 8 > group 5 > group 2. In combination groups, group 9 > group 3 > group 6. However. no significant differences were found between group 4 and 7. between group 2 and 5, and be-tween group 3 and 6. 3. SEM showed that comparably longer resin tags were distributed regularly in acid etching groups and that shorter ones irregularly in airabrasion groups. It also showed that these two kinds of tags were distributed simultaneously in combination groups.

자원 제약 조건이 공기-비용 교환 문제에 미치는 영향 분석

홍성준,류한국,유정호,이현수 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1

It has been generally accepted that cost and time are in reverse proportion. But, due to the resource constraints such as resource capacity, resource availability, resource continuity and resource level, time and cost could have unfixed relation and time-cost trade-off curves could take various forms. This study proposes the labor-related constraints affecting the time-cost trade-off problems and analyzes the effects.

리비아 대수로공사 지역의 지반특성

홍원표,남정만,김시현,이재호 중앙대학교 기술과학연구소 1996 기술과학연구소 논문집 Vol.26 No.-

리비아 사막지역의 지반특성을 연구하기 위하여 리비아 1단계 대수로공사가 실시된 지역의 지반특성을 검토하였다. 본 연구에서는 Sarir 취수원에서 Ajdabiya 저수조를 경유하여 Sirt 저수조까지의 대수로 공사지역을 따라 실시된 실내시험과 현장시험결과를 포함하고 있다. 이 지역은 내륙지역(Sarir 취수원에서 Ajdabiya 저수조까지)과 해안지역(Ajdabiya 저수조에서 Sirt 저수조까지)으로 구분하여 연구된다. 본 연구결과, 지표면 부근에 있는 모암(Cap rock)은 주로 Caliche나 석회사암(Calcarenite) 성분을 많이 띠고 있고, 이들의 깊이에 따른 강도변화는 발견할 수 없었다. 또한 모래에 대한 Ncl도 깊이에 대한 변화를 발견할 수 없었으나 이들을 종류별로 분류하였을 경우, N치가 약간 증가하는 추세를 보였다. 끝으로 해안지역의 점토에서는 지표면부근에서 조금 과압밀된 경향을 볼 수 있었으며, 내륙지역의 점토에서는 대단히 높은 팽윤포텐셜이 관찰되었다. To study geotechnical properties on Sahara desert of Libya, geotechnical characteristics in the region of the Great Man-made River Project were reviewed. A series of field and laboratory tests were carried out along the route of the conveyance lines from Sarir well field to Sirt end reservoir through Ajdabiya holding reservoir. In the view of geotechnical aspect, the research subject area can be divided into two areas ; one is the inland area(from Ajdabiya holding reservoir to Sirt reservoir). The results of this study showed that the cap rocks nearby ground surface were generally composed of caliche or calcarenite and variation of its strength according to depth could not find. Also, N value in sand did not show a trend of variation with depth however, the N value in the classified soil reveals tendency to increased. The clay of ground surface in the coastal area was slightly overconsolidated due to the desiccation of the surface soils. The clay in the inland area had high swelling potential.

In situ hybridization과 염색체 미세해부에 의한 특정 염색체 띠에 대한 유전자 발굴

홍기정,김현수,전용혁,김현,박선화 고려대학교 의과대학 1996 고려대 의대 잡지 Vol.33 No.1

Recently surmountable amounts of genes are being cloned but it is hard to define the chromosomal location and functions of these genes. In this study, a new technique was developed for cloning genes expressed in the developing human brain with confirmed chromosomal location. The mRNAs were extracted from 18 week old human fetal brain, cDNAs were made by reverse transcription from these mRNAs and Uni-amp cDNAs having Uni-amp adapters a t both ends were made for subsequent PCR. To observe the distribution of the Uni-amp cDNAs on the chromosome, fluorescent in situ hybridization was performed with biotin labeled Uni-amp cDNAs. Among the chromosome bands showing strong hybridization with the cDNAs, lq21, lq25, lq32 and lq42 were microdissected from the chromosome hybridized with unlabeled Uni-amp cDNAs and amplified by PCR with Uni-amp primers. These amplified cDNA fragments were subcloned to plasmid vectors and the nucleic acid sequences were analysed. As a result 18 different clones were confirmed the chromosomal localization. They were categorized as 4 clones of well characterized genes, 3 clones showing low homology with known genes, 5 clones of simply registered uncharacterized human cDNAs, and 6 clones of unknown genes. The evidence suggests that the technique is very useful to clone the genes that express in the developing human brain, with confirmed chromosomal location. In addition, this cloning technique can be used to discover the new genes related with neuronal development in combination with functional screening method.

초음파 공명 분광법(RUS)을 이용한 SiC 입자강화 Al 기지복합재료의 탄성계수 해석

홍순형,주영상,정용무,정현규 韓國非破壞檢査學會 1999 한국비파괴검사학회지 Vol.19 No.3

SiC 입자강화 2124Al 금속복합재료의 강화재 부피분율에 따른 탄성 stiffness를 초음파 공명 스펙트로스코피(resonant ultrasound spectroscopy: RUS) 방법을 이용하여 측정하였다. RUS 방법은 한 개의 소형 시편으로 9개의 독립변수를 가진 사방정계(orthorhombic) 탄성계수를 간단한 실험으로 측정가능함을 보여주었다. SiC 강화재 부피분율 변화에 따른 탄성계수를 측정하였는데 이 경우 초기 추정 탄성계수를 구하기 위해서 부피분율에 따른 미세조직 사진으로부터 강화재의 형상(aspect ratio)과 방향을 고려한 유효 aspect ratio 개념을 도입하였고, Mori-Tanaka 이론식에 의한 계산결과를 이용하였다. 이로부터 계산된 공진주파수와 RUS의 측정 공진주파수 사이를 최소화함으로 정확한 탄성계수를 측정하였다. 측정된 stiffnesses로부터 공학적 탄성계수인 Young's modulus를 계산하였으며, 계산된 Young's modulus와 압출방향으로 인장시험한 Young's modulus를 비교분석하였다. SiC 입자의 부피분율이 증가함에 따라 탄성계수가 증가함을 나타내었고, 탄성 stiffness의 거동은 강화재가 많이 첨가될수록 횡등방성(transversely isotropic) 이 강하게 나타났으며 이것은 압출공정에 의해 강화재 입자의 방향성 재배열에 기인한다. 한편 일정크기 시편에 있어서 기본 공진주파수가 강화재 부피분율에 따라 고주파수 영역으로 이동하는 현상이 관찰되었으며, 이로 부터 비파괴적으로 강화재 부피분율을 예측할 수 있는 가능성을 제시하였다. The dynamic elastic properties of metal matrix composites were investigated by resonant ultrasound spectroscopy(RUS). The composites used in this study consisted of 2124 aluminum alloy reinforced with different concentrations of SiC particles. RUS can determine the nine independent elastic stiffness(C )for the orthorhombic symmetry on a small specimen simultaneously. The elastic constants were determined as a function of the volume fraction. A concept of effective aspect ratio, which combine the aspect ratio and the orientation of reinforcement, was used to calculate the initial moduli from Mori-Tanaka theory for the input of RUS minimization code. Young's moduli can be obtained from the measured stiffnesses. The results show that the elastic stiffness increases with increment of the particle content. The behavior of elastic stiffness indicates that the particle redistribution induced by the extrusion process enlarges the transversely isotropic symmetry as the fraction of reinforced particles increase. This relationship could be used for determination of the volume fractions of reinforcement as a potential tool of nondestructive material characterization.

주행속도에 따른 부상마그네트의 특성을 고려한 상전도 자기부상시스템의 부상제어에 관한 연구

玄東石,洪正杓,鄭因城,許眞,尹相伯 창원대학교 공작기계기술연구센터 1999 연구업적집 Vol.1 No.1

A collective controller for electromagnetic suspension (EMS) system considering the speed characteristics of electromagnets is presented. The speed characteristics of the electromagnet are analyzed by finite element method (FEM) and Neural Network algorithm is used for the controller considering speed. The proposed controller is examined and the dynamic characteristics are compared with those of other controllers. The simulation results show that proposed controller has a better performance at high speed.