Micronucleus test를 이용한 수종 결합용레진과 상아질결합제의 돌연변이 유발에 관한 연구

이용근,전혜림,김철위,윤숙진 大韓齒科器材學會 1992 대한치과재료학회지 Vol.19 No.1

The purpose of this study was to evaluate the mutagenicity of the bonding resins of dental composites and the dentin bonding agents. Eight bonding resins, six dentin bonding agents and distilled water (negative control) were administered orally and cyclophosphamide (positive control) was administered intraperitoneally to the mice. The mice were killed by cervical dislocation at 24 hours after administration and the femurs were removed and dissected. The bone marrow cells were collected and smeared on glass slides and stained with haematoxylin-eosin staining method and were observed with light microscope(X450). The following results can be drawn: 1. The bonding resins of dental composites and the dentin bonding agents were tested in this study seemed to be non-mutagenic. 2. The numbers of micronucleated polychromatic erythrocytes were similar both in the bonding resins of dental composites and the dentin bonding agents. 3. In the case of some products(AP, SC' and AA), the number of micronucleated polychromatic erythrocs was high beyond other products.

교정용 선재와 브라켓 사이의 마찰력에 관한 연구

김철위,박영준,이용근 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2

Mechanical friction makes the orthodontic tooth movement require greater force than the biological tooth movement. Friction is affected by the size, shape, and material of both the bracket and the wire. This study was designed to investigate the effect of material or size of orthodontic brackets and orthodontic wires on the amount of frictional forces generated during simulated tooth movement. A testing apparatus was designed to simulate the clinical situation in which the center of resistance of a tooth is not on the same plane as that of bracket, thereby resulting in some tipping of the bracket slot relative to orthodontic wire (100 gram weight was suspended). In angulated and non-angulated experimental condition, the orthodontic wires were drawn through the testing apparatus with the speed of 2mm/minute. The results were as follows : 1. In both of the cases of the metal bracket and ceramic bracket, the frictional forces were greater in angulated experimental group than non-angulated group. In both of the non-angulated and angulated experimental group, the frictional forces of ceramic brackets were greater than those of metal brackets. In most of cases, these differences were statistically significant(p<0.05) with a few exceptions. 2. In general, the frictional forces of orthodontic wires with circular cross-cut surface were lower than those wires with rectangular cross-cut surfaces. But there was no statistically significant correlation between the size of orthodontic wire and frictional forces. 3. There was no difference between the frictional of the stainless-steel orthodontic wires and those of the cobalt-chromium orthodontic wires, but the frictional forces varied depending on the measuring condition or brand of the wires. 4. The frictional forces of β-titanium orthodontic wires were significantly higher than those of stainless-steel orthodontic wires were cobalt-chromium orthodontic wires.

시차주사열량분석기를 이용한 치과용 접착시멘트의 경화기전 및 반응열에 관한 연구

김철위,이용근,윤태호,김효종,남세진 大韓齒科器材學會 2000 대한치과재료학회지 Vol.27 No.3

The working time of dental cement has a close relation with the setting time, where the setting reaction can be said as the result of the chemical reaction between cement liquid and powder. The purpose of this experiment was to investigate the setting characteristics and setting rate of dental cements by measuring the exothermic heat(Joule/gram) from the setting reaction at specified times using a differential scanning calorimeter (Differential Scanning Calorimeter, DSC 204, TASC 414/3A Controller, Netzche, Germany). Graphs of time-exothermic heat at 37℃ isothermal condition, showing the setting reaction of dental cements were plotted. Three types of luting cements studied were zinc-phosphate cement (ZPC), polycarboxylate cement (PCC), and glass ionomer cement (GIC). The effects of powder-liquid ratio on the setting characteristics of cements were also included. The amount of heat (calory) released per one gram of cement was calculated at each specified time, and was analyzed. ANOVA and Scheff's multiple comparison test (p=0.05) were used for statistical analysis using SPSS/PC+. The setting rate of cement was not constant during the setting reaction, and different setting characteristics were observed depending on the type of cement and powder/liquid ratio. Generally, 70∼90% of the setting reaction, measured by the exothermic heat release, occurred within 5 minutes after mixing. The exothermic heat released by ZPC was very high immediately after mixing, and the duration of the heat release was prolonged compared with other cements. The exothermic heat release of PCC finished most rapidly. It was generally observed that the amount of heat release (rise in temperature) per one gram of cement was highest for ZPC, followed by GIC, and then PCC. However, heat release during the first 2∼5 minutes after mixing was highest for GIC, followed by ZPC and then PCC. According to the Scheff's multiple comparison test, the duration of the total setting reaction did not show any significant difference among the cements(p>0.05), and also among the different power/liquid ratio groups(p>0.05). It was observed that more heat was released with the lower powder/liquid ratio than the higher powder/liquid ratio.

결핵성 육아종에서 Thioredoxin peroxidase-2 의 발현

박근호,유형륜,정영진,윤기중,한원철,유대열,문형배 圓光大學校 醫科學硏究所 1999 圓光醫科學 Vol.15 No.2

Background: Thioredoxin peroxidase(TPX) is a kind of recently discovered antioxidant enzyme which react as rapid hydrogen ion donor for the removal of hydroperoxide. The action and distribution of the TPX was poorly understood in the human diseases. This experiments were designed for the study about the distribution of the TPX in the chronic granulomatous inflammation and about the correlation between the expression of TPX and the site of inflammation, histological activities of tuberculous inflammation or existence of mycobacterium in the inflammatory foci. Methods: The immunohistochemical stains were performed for the localization of the TPX-2 in the epithelioid cells, giant cells and lymphocytes in the chronic granulomatous inflammation. The tissue sections were obtained from the paraffin blocks of the 54 cases of tuberculosis (lung 21 cases, lymph node 12 cases, bone and soft tissue 12 cases, kidney 9 cases; active 33 cases, inactive 21 cases by the histologic classification; presence of mycobacterium 15 cases, no mycobacterium 39 cases by PCR reaction). Results: The expression of TPX-2 was 16.7% in the giant cells, 27.8% in the epithelioid cells and 100% in the lymphocytes of tuberculous inflammations. The expression of TPX-2 in the giant cells and epithelioid cells of the tuberculosis were 28.6% and 57.1% of the pulmonary tuberculosis; 33.3% in each cells of the renal tuberculosis; 0% in each cells of the lymph node or bone and soft tissue tuberculosis. The expression of TPX-2 in the giant cells and epithelioid cells were 9.1% in each cells of the active tuberculosis and were 28.6% and 57.1% in each cells of the inactive tuberculosis by histologic classification. The expression of TPX-2 in the giant cells and epithelioid cells was 40% in each cells of tuberculosis which mycobacteria were detected and the expression of TPX-2 was 7.7% and 23.1% in each cells which mycobacteria were not detected by PCR reaction in the paraffin embedded tissue. Conclusions: The above results were summarized that the TPX-2 in the giant cells and epithelioid cells were more frequently expressed in the inactive tuberculosis than in the active tuberculosis. These results suggest that the TPX-2 is a kind of regulating or suppressing factors in the activity of the tuberculosis.

치과용 저채도, 고투명도 콤포짓트레진의 색상특성에 관한 연구

이용근,임범순,김철위 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.1

최근 개발된 저채도 및 고투명도 색상의 콤포짓트레진을 대상으로 미중합 상태, 중합후 및 열순환 후의 색상을 측정하여 중합 과정과 열순환 후의 변색도를 기존 색상의 콤포짓트레진과 비교하였고, Vita 색조가이드 및 Bioform 색조가이드의 색상과의 관계를 보았다. 또한 색측정 방법 및 색상을 측정할 때 사용하는 표준광원의 종류에 따른 색상의 차이를 분석하였다. 2종의 콤포짓트레진을 대상으로 분광광도계(CM-3500d, Minolta, Japan) 로 정반사광 제거방식 (SCE) 및 정반사광 포함방식 (SCI) 등 두 종의 측정방법과 색상측정용 광원으로 표준광원 C, A 및 D65 를 이용하여 색상을 측정하였다. 시편의 열순환은 5~55 ℃에서 3,000 회 실시하였다. 색조가이드의 색상은 색조 탭의 순면을 2,400 번까지 사포로 연마하여 분광광도계의 측정광의 직경인 3mm 이상의 평평한 면을 만든 후 측정한 바, 다음과 같은 결과를 얻었다. 1.표준광원의 차이에 의한 색차(ΔE*)는 저채도 색상이 기존 색상의 콤포짓트레진보다 중합전, 중합후 및 열순환 후 조건에서 모두 크게 나타났으며, 표준광원 A는 C와 D65 와 차이가 큰 것으로 나타났다. 또한 SCE 방식과 SCI 방식으로 측정한 색차는 유사하였다. 2.중합전과 중합후의 색차 및 열순환 후의 변색도는 저채도 색상군의 경우가 표준광원의 종류와 무관하게 기존 색상군의 콤포짓트레진보다 유의하게 높았으며 (p〈0.05), SCE 방식으로 측정한 색차는 SCI 방식으로 측정한 색차보다 높았다. 3.색조가이드의 색좌표중 CIE L*과 CIE b* 는 표준광원 A로 측정한 값은 다른 광원을 사용하였을 때보다 높았고, CIE a* 는 표준광원 A와 D65로 측정한 값이 C로 측정한 경우보다 높았다. 4.Vita 색조가이드의 색상계열(A, B, C, D)은 SCE 방식으로 측정한 L* 값 및 a* 값과 음의 상관관계가 있었으며 다중회귀계수는 0.87이었다. 또한 Chromascop 색조가이드의 색상계열 (100, 200 등) 은 SCI 방식으로 측정한 L* 값과 음의 상관관계를 보였다. 5.저채도 및 고투명도 색상을 포함하는 체계적인 색조가이드의 개발이 필요하다.

치과주조용합금의 물성에 관한 비교연구

김철위,이용근 大韓齒科器材學會 1992 대한치과재료학회지 Vol.19 No.1

The purpose of this study was to evaluate the characteristics of five gold-silver-palladium alloys, six H.E dental casting alloys, three dental casting nickel-chromium alloys, four porcelain metals and four dental casting cobalt-chromium alloys being used in Korea. The following properties were studied: Vicker's hardness, ultimate tensile strength, elongation rate, melting temperature and yield strength. These tests were performed according to the KDA Specification No. 6: Dental casting cobalt-chromium alloys, KSP 5101: Dental nickel-chromium alloy plate, RANSI/ADA Specification No. 5: Dental casting alloys, RANSI/ADA Specification No. 14: Dental base metal casting alloys, JIS T 6101: Dental casting gold-silver-palladium alloys, JIS T 6102: Dental nickel chromium alloy plate, ISO Specification No. 1562: Dental casting gold alloys and FDI Specification No. 7: Dental casting gold alloys. From the experiments, the following results can be drawn: 1) In case of the dental casting gold-silver-palladium alloys, the Vicker's hardness number was VHN 171 to VHN 229, the ultimate tensile strength was 633.1 ±148.5 MPa to 771.9 ±29.5 MPa, the elongation rate was 19.7% to 23.3%, the yield strength was 616.0+141.3 MPa to 751.0±20.4 MPa and the melting temperature range was 937℃ to 1,221℃. 2) In case of the H.E dental casting alloys, the Vicker's hardness number was VHN 120 to VHN 234, the ultimate tensile strength was 329.4 MPa to 681.5 MPa, the elongation rate was 14.0% to 38.9%, the yield strength was 304.9 MPa to 820.1 MPa and the melting temperature range was 899℃ to 1,125℃. 3) In case of the dental casting nickel-chromium alloys, the Vicker's hardness number was VHN 77 to VHN 106, the ultimate tensile strength was 473.6 ±34.0 MPa to 501.7 ±31.7 MPa, the elongation rate was 16.11% to 75.36% and the yield strength was 430.1 ±40.8 MPa to 450.9 ±48.6 MPa. 4) In case of the dental porcelain alloys, the Vicker's hardness number was VHN 206 to VHN 300, the ultimate tensile strength was 784.3 ±12.1 MPa to 1,114.8 ±24.5 MPa, the elongation rate was 20.40% to 39.10% and the yield strength was 749.2 ±11.3 MPa to 1,049.7 ±23.6 MPa. 5) In case of the dental casting cobalt-chromium casting alloys, the Vicker's hardness number was VHN 155 to VHN 266, the ultimate tensile strength was 671.8 ±339.8 MPa to 876.8 ±26.2 MPa, the elongation rate was 16.77% to 24.46% and the yield strength was 676.1 ±295.0 MPa to 841.7 ±34.6 MPa.

화상 환자에서 발생한 외과적 중재술을 요하는 감염성 심내막염 2예

김근숙,이태유,정연손,최창순,최민호,류제헌,김철홍,조구영,우흥정 대한감염학회 2003 감염과 화학요법 Vol.35 No.3

감염성 심내막염은 화상 후에 발생할 수 있는 치명적인 합병증이다. 임상 증상은 일반적으로 없는 경우가 대부분이고 지속되는 발열과 양성 혈액 배양 검사가 유일하다. 감염의 다른 확실한 원인 없이 발열과 양성 혈액 배양 검사가 있을 때는 감염성 심내막염을 강력하게 의심해야 하며 심장 초음파로 진단 가능하다. 감염성 심내막염은 사망률은 높지만 초기에 진단하면 항생제 정주를 지속하는 것으로 치료할 수 있다. 저자들은 화상환자에서 발생한 수술적 처치를 필요로 하는 감염성 심내막염 2예를 경험하였기에 보고하는 바이다. Infective endocarditis is a rare but fatal complication following burn injury. The clinical presentation is silent, but with persistent fever and positive blood culture. The manipulation of clinical care as well as the burn wound itself and immunosuppression caused by extensive bums puts the burn patients at risk of bacteremia. Staphylococcus aureus and Gram-negative bacilli are most common pathogens of infective endocarditis following burns. We report herein two cases of infective endocarditis in the burn patients who requires surgical intervention. The first case was caused by Pseudomonas aeruginosa with complication of multifocal pneumonia, and the second case by coagulase-negative stapylococcus with cerebral hemorrhage.

광합성세균에 의한 미생물막의 형성

오광근,이철우,전영중,이재홍 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.6

홍색비유황 광합성세균인 Rhodopseudomonas capsulata를 선택하여 packed-bed reactor에서 미생물막을 형성할 때, porous ceramic bead가 다른 담체에 비해 우수하였고, 일정한 유입농도하에서 체류시간(hydraulic retention tiem, HRT)이 짧을수록 미생물막 형성이 양호하였으며, 그 때 반응기내의 세포농도는 11,400mg/l로 현탁처리시의 세포농도에 비하여 3~8배 증가하였다. PBR에서 미생물막의 형성은 cell attachment, microcolony formation, biofilm formation의 단계를 거쳐 형성되는 것으로 관찰되었으며, PBR이 FBR보다 안정적인 미생물 부착을 보였고 특히 PBR에서는 BOD용적 부하가 15gBOD/ℓ·day 이상이 되어도 미생물막의 부착비율은 90% 이상을 유지하였다. 전자현미경으로 담체의 표면 및 내부에 고정화된 광합성세균을 확인할 수 있었다. The formation of microbial films(biofilm) by a non-sulfur phototrophic bacteria, Rhodopseudomonas capsulata, on inorganic media was studied. Porous ceramic beads(PCB) were superior to other immobilizing media for the biofilm formation in a packed-bed reactor. It was found that the formation of microbial films favored a lower hydraulic retention time, showing a higher ratio of cells attatched to the media to those suspended in the solution. The cell concentration in the biofilm reactor was as high as 11,400 mg/ℓ, which is 8-folds of the cell concentration in a ordinary suspended treatment. It was observed that the formation of microbial film by R. capsulata followed a general serial process of cell attachment, microcolony formation, and biofilm formation. The microbial films thus formed was very stable even for an extremely high volumetric BOD loading rate of 15 gBOD/ℓ·day. The scanning electron micrographs of the microbial films showed that the cells were attached to both the surface and pores of the media.

색광원을 이용한 그림자식 무아레 토포그래피에서 물체의 높낮이 판별

陸根鐵 公州大學校 基礎科學硏究所 1994 自然科學硏究 Vol.3 No.-

2개의 색광원과 3개의 색광원을 이용해서 그림자식 무아레 무늬에서의 물체의 높낮이를 판별할 수 있는 2가지 실험법을 제안하고 실험하였다. 그 결과 2개의 색광원에 의한 실험법에서는 주기적 색구조로, 3개의 색광원에 의한 실험법에서는 무아레 후린지의 색배열에 의해 물체의 높낮이로 판별할 수 있음을 밝혔다. In this paper, The method for determining the depression and elevation in shadow moire fringes is proposed and experimently realized with two or three colored light sources. The experiments show that the depression and elevation of the object can be determined by the periodicity or the order of the colored fringes patterns.

감사인의 양적 중요성 판단 기준의 적용에 관한 연구

金大根,趙徹衍 韓日經商學會 2001 韓日經商論集 Vol.21 No.-

This thesis studied if, under the varied audit environment, there is any significant difference on the degree of strictness (rigidity) of an auditor's quantitative materiality judgement when an auditor formulates audit opinion regarding to the exception out of gathered evidence. This study defined the degree of strictness as : the lower the average of threshold between unqualified and qualified opinion, the stronger the degree of strictness of an auditor's quantitative materiality judgment. This research found the followings: First, there is no statistically significant difference in the degree of strictness of an auditor's quantitative materiality judgment affected by the scale of the auditor. Second, the scale of the client affects an auditor in the degree of strictness of an auditor's quantitative materiality judgment. Third, there is a significant difference in the degree of strictness of an auditor's quantitative materiality judgment for listed vs. non-listed corporation. Fourth, the higher the debt ratio of the client, the stronger the degree of strictness of an auditor's quantitative materiality judgment. Fifth, an auditor applied quantitative materiality judgment more strictly for the client corporation with any turnover between net profit and net loss.