유기용제 취급근로자들의 요중대사물질과 말초임파구 자매염색분체교환 발현빈도에 관한 조사연구

김돈균,황인경,류철인,이수일,정갑열,이용환,이충렬,현원일,김석봉,전용덕 大韓産業醫學會 1990 대한직업환경의학회지 Vol.2 No.1

저자들은 유기용제 취급여성근로자 90명을 대상으로 1988년 7월부터 1989년 8월까지 말초혈액임파구에서의 자매염색분체교환의 발현빈도를 조사하고 이들의 업종, 근속연수, 요중마뇨산 농도등이 자매염색분체교환의 발현빈도에 미치는 영향을 조사하였으며 그 결과를 요약하면 다음과 같다. 1. 유기용제 취급근로자들의 말초혈액임파구에서의 자매염색분체교환의 발현빈도는 대조군에 비하여 유의하게 증가되었다. 2. 말초혈액임파구에서의 자매염색분체교환의 발현빈도가 가장 높은 업종은 프라스틱제품 제조업이었다. 3. 근속연수가 말초혈액임파구에서의 자매염색분체교환의 발현빈도에 미치는 영향은 현저하지 않았다. 4. 요중마뇨산농도와 말초혈액임파구에서의 자매염색분체교환의 발현빈도간에는 유의한 상관관계가 있었다. In order to know the possibility of utilizing the sister chromatid exchanges as an index which could evaluate the effect of organic solvents on the health in industrial workers, the authors studied the effects of the inductivity of sister chromatid exchanges in peripheral lymphocytes from 90 female workers expoxed to organic solvents and 20 non-exposed female workers. The results obtained were as follows : 1. The frequency of sister chromatid exchanges in peripheral lymphocytes from 90 female workers exposed to organic solvents was significantly increased in comparison with 20 control subject. 2. The frequency of sister chromatid exchanges was significantly increased in the workers who were employed in the manufacture of plastic materials than the other manufactures. 3. There were no significant differences in the frequency of sister chromatid exchanges by carriers of the exposed workers.

초음파속도법을 이용한 혼화재 및 섬유 사용 콘크리트의 압축강도 추정에 관한 연구

김정섭,신용석,노성열 朝鮮大學校 建設技術硏究所 2007 建設技術硏究 Vol.27 No.1

This study aims to estimate strength approximate to actual concrete strength by presenting appropriate non-destructive strength estimation expression with admixtures such as fly ash, blast furnace slag and silica fume which are used as cement substitute and polypropylene fiber and steel fiber and owing to their s of cement owing to their equal conditions to blending characteristics of concrete used for domestic structures and their recyclable properties. In case of ultrasound velocity, equation by Japanese Architecture Society was estimated 4%~11% higher than destructive strength till 60 days of age, but as age progresses, i is estimated to 15% lower than destructive strength and remaining suggested equation was estimated 3%~27% lower than destructive strength in almost age. As a result of comparing error rates between conventional suggested equations and this estimation equations, there are a little differences by age, but error rate of this study was reduced to 0.6%~18.6% by ultrasound velocity method and it is judged that it is desirable to be used for concrete using admixture and fiber

순환골재를 사용한 콘크리트 보의 구조적 특성에 관한 연구

김정섭,신용석,노성열 朝鮮大學校 建設技術硏究所 2007 建設技術硏究 Vol.27 No.1

This study identified materials and dynamic characteristics of reclaimed aggregates affecting reinforced concrete through materials and supplementary tests to use broken red bricks and waste concrete as substitutes of concrete and obtained the following results. As a result of the bending specimen test according to types of reclaimed aggregates, it was found that when normal concrete was compared with reclaimed concrete. RBA 30% specimen showed 99-104% of yield load and RCA 30% specimen showed 102-104% of yield load, which were the yield load and the largest yield load of normal concrete. Therefore, it is believed that RBA 30% and RCA 30% specimens has almost similar bending strength to ormal concrete. To sum up the results of material and supplementary tests, the mixed aggregates showed almost the same compressive strength and bending strength compared to that of normal concrete when 30% of broken red bricks and waste concrete were mixed. So this study suggests that they can be applied as thick aggregates.

반발경도법에 의한 혼화재 및 섬유사용 콘크리트의 압축강도 추정

김정섭,신용석,노성열,김정훈 朝鮮大學校 建設技術硏究所 2007 建設技術硏究 Vol.27 No.2

This study aims to estimate strength approximate to actual concrete strength by presenting appropriate rebound method strength estimation expression with admixtures (fly ash, blast furnace slag, silica fume) which are used as cement substitute and polypropylene fiber and steel fiber and owing to their s of cement owing to their equal conditions to blending characteristics of concrete used for domestic structures and their recyclable properties. In case of rebound hammering, equation by Japanese Architecture Society was estimated 26~40% higher than destructive strength and remaining suggested equation was estimated 2%~18% lower. In case of ultrasound velocity, equation by Japanese Architecture Society was estimated 4%~11% higher than destructive strength till 60 days of age, but as age progresses, is estimated to 15% lower than destructive strength and remaining suggested equation was estimated 3%~27% lower than destructive strength in almost age. In case of complex methods, all suggested equations were estimated to 24%~94% higher than destructive strength. Since application of existing expression of normal concrete against concrete using admixtures and fiber causes error rate, this study suggests the following estimation expression depending on the kind of admixtures and fiber of concrete using them and position of non-destructive experiment. C-N f_(cu)=1.6R-25.43(R²=0.90), C-FA f_(cu) = 1.07R-8.76 (R²=0.82), C-BF f_(cu)=1.46R-23.09(R²=0.92) C-SF f_(cu) = 1.55R-22.96(R²=0.89), C-PP f_(cu) = 1.16R-12.24(R²=0.73), C-S f_(cu)=0.99R-8.07(R²=0.86)

티타늄의 산화 조건에 따른 산화막의 특성 및 인산칼슘 생성에 미치는 영향

김인,양홍서,박연준,송호준,이용렬 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.3

The objective of this study was to evaluate the changes of micro morphology, roughness and crystalline structure of titanium surface after various oxidation treatments. Moreover, the effect of titanium surface oxide characteristics on the formation of calcium phosphate in Eagle's MEM. Commercially pure Ti disks were treated at various thermal conditions of 530℃ (Ti-530), 600℃(Ti-600), 700℃(Ti-700), 800℃(Ti-800), 900℃(Ti-900), and 1000℃(Ti-1000), respectively, and as received cp Ti (AS-R) and passivated cp Ti (PAS) were used as comparison groups. Surface characteristics were investigated using FE-SEM, profilometer and XRD. After immersing each sample in MEM for 7days, calcium phosphate (Ca-P) formation was evaluated using FE-SEM and EDS. Crystallites of 10~30nm-size were observed on the surface of Ti-530 and Ti-600 samples. Needle-like crystals were formed on Ti-700 samples, and the crystal grain size was increased dramatically as the temperature increased higher than 800℃. The roughness of Ti-530 was higher comparing to AS-R and PAS, and the roughness decreased in the treatment range of 530-700 with dense crystalline oxide formation. However, at treatment temperatures higher than 800℃, the roughness increased and its degree was depended to the size of the crystals. The anatase structures were observed in Ti-530 and Ti-600, and anatase and rutile structures were co-existed in Ti-700 specimen. Only rutile TiO_(2) were observed in Ti-800, Ti-900 and Ti-1000 specimens. The Ca-P formation on AS-R and PAS specimens was low in MEM solution. However, the Ca-P formation was well observed on heat-treatedgroups, and its degree of formation and micro-morphology was different by the specimen groups. The crystalline and chemical structure, micro-morphology, and surface roughness of titanium were various by the conditions of heat treatments, and the grain size and crystal structure of titanium oxide affected on the degree of Ca-P formation on Ti samples in MEM solution

합작기업의 지식습득에 영향을 미치는 요인에 관한 연구 : 한국에 진출한 국제합작투자기업을 중심으로

박영렬,박용석,김민정 한국국제경영학회 2002 國際經營硏究 Vol.13 No.2

본 연구는 한국기업과 외국기업이 투자하여 설립된 국내 국제합작기업에서 신제품개발과 관련된 지식 또는 노하우를 습득하는 데 영향을 미치는 요인들을 지식관련, 합작기업관련, 파트너관련변수로 분류하여 각 요인과 지식습득정도와의 관계에 대한 가설들을 자원·지식기반관점과 거래비용이론에 근거하여 도출하였다. 본 연구는 67개의 설문응답을 기초로 진행되었으며, 실증분석 결과 합작기업관련 요인인 학습역량과 합작동기가 지식습득정도와 정의 유의한 관계에 있음이 검증되었다. 또한 파트너관련 요인인 파트너간의 갈등이 높을수록 지식습득의 정도가 낮을 것이라는 가설도 유의수준 내에서 채택되었다. This paper understands cross-border joint ventures as one of the means to absorb knowledge from partners. Based on a resource-based perspective, a knowledge-based viewpoint, and transaction costs theory, determinants of knowledge acquisition within international joint ventures (IJVs) are grouped as knowledge-, IJV, and relation-specific. We have gathered 67 survey questionnaires, which were used to test hypotheses with multiple regression model. The test results indicate that firms' absorptive capacity and motivation of IJV have positive relations with the degree of knowledge acquisition. Conflict among partners has a negative impact on knowledge acquisition as expected.

티타늄 상에 강유전성 barium titanate 박막 형성과 분극처리에 의한 유사체액 내에서의 calcium phosphate 생성 증진

박영준,이용렬,황규석,김은주,임용무,이기헌 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.2

This study was performed to fabricate a ferroelectric barium titanate (BaTiO₃, BTO) thin film on Ti substrate and to evaluate the effect of poling treatment for the improvement of calcium phosphate (Ca-P) formation. BTO thin-film was spin-coated on Ti substrate by dipping-pyrolysis technique using coating sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-heating temperature of the BTO thin film was performed at 500℃ because organic-solvent was completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 650, 700, 750, 800, 850℃, respectively. By repeating the coating and pre-heating procedure gor 20 times, homogeneous thin film of 0.7㎛ thickness could be fabricated, and it performed well during the poling treatment without breakdown. The final heating treatment of the BTO thin film at 750℃ produced a homogeneous crystalline structure without heterogeneous TiO₂formation, which was confirmed by field emission scanning electron microscope (FE-SEM) and X-ray diffraction analyser (XRD). An average grain size of 20∼30 ㎚ were confirmed by SEM observation. The final heat-treated BTO thin-films were polarized (Ep = 5 V/㎛) from 160℃ to 25℃ in heating chamber for 2 h. The negatively poled BTO thin film (N-BTO), non-poled BTO thin film (BTO), Ti substrate (Ti), and 600℃ heat-treated Ti (Ti-O) were immersed in SBF and Eagle's MEM solution for 15 days at 37℃. After the immersion period, the morphological and compositional changes of the surfaces were investigated using a FE-SEM and an energy dispersive X-ray spectrometer (EDX). After immersion in simulated body fluid (SBF), sodium chloride (Nacl) crystals were formed on Ti, Ti-O, and BTO surfaces due to anion adsorption (Cl), while Ca-P crystals were formed on N-BTO surfaces. We assumed that rapidly adsorded cations (Ca²□ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals. In MEM, sodium chloride (NaCl) was formed on Ti, and Ca-P layer including NaCl was formed on Ti-O. Weak and sparse Ca-P layers were formed on BTO, while thick, homogeneous, and dense Ca-P layer was formed on N-BTO, which was confirmed by FE-SEM and EDX. These results demonstrated that introducing a N-BTO on Ti is an effective method for the improvement of Ca-P formation in SBF and MEM. In conclusion, negatively charged ferroelectric BTO thin-film on Ti would improve the possibility of implant osseointegration.

치과주조용 Ti-Zr-Cr계 합금에서 Cr 함량변화가 부식저항성에 미치는 영향

박영준,강후원,이용렬,송호준,김민강 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.4

The purpose of this study was to develop new dental casting titanium (Ti) alloys having an excellent mechanical properties and good corrosion resistance as a substitute for c.p Ti and Ti-6Al-4V alloy (control groups). Ti-20Cr, Ti-2OZr and Ti-20Zr-XCr (X=2, 5, 10, 15) alloys (experimental groups) were designed for dental casting Ti alloys. Prior to casting prccedure, mother alloys were prepared by using vacuum arc melting with skull melting method. Argon-arc melting and argon/vacuum-pressure casting machine were used for making the specimens. The hardness, microstructure, and corrosion resistance were evaluated by using Vickers microhardness measurement, FE-SEM, and anodic polarization test. The results were as follows: 1. The Vickers microhardness (Hv) of Ti and Ti-6Al-4V alloy showed the values of 210 and 352, and Ti-20Cr and Ti-20Zr alloys showed the values of 341 and 259, respectively. As the Cr content increased from 0 to 15 % in Ti-20Zr-XCr (X=0, 2, 5, 10, 15) alloys, the Hv increased from 259 to 298, 457, 344, and 351, respectively. The microstructure of Ti-20Zr-XCr specimens showed significant difference by the concentration changes of Cr content showing acicular crystalline structure for Ti-20Zr-2Cr and Ti-20Zr-5Cr, and equiaxed crystalline structure for Ti-20Zr-10Cr and Ti-20Zr-15Cr. 2. Open-circuit potentials (E_(∝)) were rapidly decreased followed by steadiness as time elapse in all experimental groups except in Ti-20Z group. Ti-2OZr group showed an increase in E_(∝), from the first. 3. In potentiodynamic anodic polarization tests, all experimental groups showed more noble corrosion potential (E_(corr) than that of Ti-6Al-4V, and more basic E_(corr) than that of Ti. Especially, Ti-20Zr-10Cr alloy showed most favorable corrosion resistance among Ti-Zr-Cr alloys. 4. For Ti-20Zr-10Cr, Ti-20Zr-15Cr, and Ti-20Cr groups, which have more than 10% Cr content, the secondary corrosion potential shifted to noble direction in larger amounts than in the cases of control and other experimental groups. From these results, it was concluded that newly formulated Ti-20Zr-10Cr experimental alloy have adequate hardness and high corrosion resistance, and this alloy is promising candidate for a successful dental casting alloy.

활성화 수피를 이용한 중금속 흡착제 개발

박창진,양재의,유경열,장용선,김원일 한국환경농학회 2004 한국환경농학회지 Vol.23 No.4

The objective of this research was to develop the adsorbent for heavy metals by activating the bark sample. Barks from pine tree with diameters of 2~4 mm were activated in the muffle furnace under a high relative humidity condition at temperatures of 600~900℃. The removal efficiency of the activated bark (ACTBARK) for Cu and Cd was temperature dependent showing the order of 900℃ > 800℃ > 700℃ > 600℃. The critical temperature was considered to be 900℃ to become an efficient adsorbent for Cu and Cd. The bark samples activated at temperatures lower than 700℃ showed a less removal efficiency than the crude bark The ACTBARK activated at 900℃ removed more Cu and Cd from solution than the commercial activated carbon and charcoal. The ACTBARK (activated at 900℃) adsorbed all of the Cu and Cd in solution with concentrations less than 150 mg/L. The selectivity of the ACTBARK was in the order of Cu>Zn>Ni>Pb>Fe>Cd>Mn.

구리의 전기석출시 젤라틴이 물성에 미치는 영향

신석재,강현춘,안형환,강안수,김용렬,한성만,이한섭 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

In the electrodeposition of copper foil for preparing printed circuit boards, a little amount of gelatin as a addition agent has been used for the better characteristics of a coat of electroplating. Gelatin modifies the physical properties such as mechanical strength, matte-side roughness, ultimate tensile strength(U.T.S), and elongation of copper foil, furthermore gelatin have influence on the structure of electrodeposits and the cathode polarization. The electrolyte used was of a composition; CuSO₄·5H₂O 300g/ℓ, H₂SO₄ 100g/ℓ, NaCl 10 ppm as a brightner, and was gelatin 0-7 ppm as a addition agent. Current density was 50 A/dm², and the temperature of electrolytic bath was 50 to 52 ℃. Experiments showed that the optimum gelatin concentration was 5 ppm with the consideration of the numbers of electrodeposited nuclei. And the nuclei numbers was sharply increased under 5 ppm, but was almostly constant above 5ppm. Average matte-side roughness by Surfcorder was gradually increased with the increasing gelatine concentration up to 2 ppm, and maximum roughness was observed at 2ppm. The roughness showed gradual decrease within the concentration range of 2 to 4 ppm, and was almost constant above 4ppm . Within the gelatine concentration range of 0 to 7 ppm, as the concentration increased, UTS was increased and elongation was decreased logarithmically. Also, in comparison between UTS and elongation, gelatin was identified as an addition agent acting inversely.