석출상 입자의 기지 금속 결정립 성장에 미치는 영향

권해욱 嶺南大學校 工業技術硏究所 1990 연구보고 Vol.18 No.2

The continuity equations for the growths of precipitate particles and matrix grains were solved by using the continuous distribution functions. The average size of precipitate particles at a given time was equal to the critical size at that time and the average grain size of steady state was 8/9 of the critical grain size for the given time. From the interactions between those two, abnormal grain growth appeared to occur when r=9R.This result was applied to the austenite grain growth under the influence of AIN particles.

고주파 유도로 라이닝용 마그네시아계 내화 재료 개발

권해욱,이해성 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.1

The abilities and fading behaviors of 5 different inoculants were evaluated by the thermal analyses of the melts which were held at constant temperature after addition in induction furnace. The silicon content was preserved at the high holding temperature of 1450∼1500℃, which reduced by oxidation at the low one. The inoculation temperature should be higher to obtain better and reproducible result. The inoculation performance of Ba-Si was the best on the bases of effect and fading behavior

引張拘束 龜裂試驗에 依한 ABS EH32鋼 熔接部의 低溫龜裂 感受性

權海旭,金大憲,金星秀 영남대학교 공업기술연구소 1984 연구보고 Vol.12 No.1

Cracking of the welded zone of high strength steel is one of the most important factors of weldability and many kinds of test methods have been proposed to study that. In this study, cold cracking susceptibility of welded zone for high strength steel (ABS EH32 steel) with the shielded metal are welding was investigated by the tensile restraint cracking test. Effects of diffects of diffusible hydrogen contents on root cracking, lower critical stress, crack initiation and fracture method, hardness distribution of the welded zone and fractography were mainly investigated. The wet electrodes with higher diffusible hydrogen contents showed lower the critical lower stress level than the dried ones. Because of the hydrogen embrittlement, the heat affected zone by using the wet electrodes had higher hardness values than that by using the dried ones. Fracture surface of the heat affected zone with the wet electrodes showed mainly brittle fracture (intergranular and cleavage) and that of the weld metal also showed partially that due to the hydrogen embrittlement.

주철의 기계적 성질을 제어하기 위하여 고려하여야 할 몇 가지 기본 인자

권해욱 한국주조공학회 2003 한국주조공학회지 Vol.23 No.4

鑄鐵의 熔接 : 1970年代 文獻 小考 A Survey during 1970's

權海旭 嶺南大學校 工業技術硏究所 1985 연구보고 Vol.13 No.1

. This study was initiated as a literature search for the paper on the subject published during 1970's. The difficulties most encountered in the welding of iron castings were identified. The problems included: (1) solidlfication and fusion of the weld and base metals, (2) solid state transformation in the heat affected zone, and (3) weld-metal dilution. Solidification was controlled by using low heat input, inoculations, weld metal composition with carbon equivalent close to eutectic, and by slow cooling rates not higher than 10℃/s. Fusion of the base metal was controlled by buttering and low heat input so that a narrow fusion zone with isolated white iron colonies could be obtainted. A direct relationship between preheating, cooling rate and peak HAZ herdness was established. Low heat input, "Quench-weld" techniques, buttering, and the use of nickel electrodes were found to relieve shrikage stress, thus preventing HAZ cracking. Replacing silicon by aluminum/calcium as inoculants were reported to result in a more weldable iron casting. Controlled addition of niobium, which formed stable carbide in the fusion zone and HAZ, was found to improve the weldability in D2 irons which contained 18-20% nickel. weld-metal dilution could be controlled by buttering and limiting heat input. Post-weld heat treatment was found to be less important amidst the improvements in the state of art of iron casting welding. Yet the weldment could still be benefited by a moderate post-weld heat treatment in improving dimensional stability, ductility, and resistance to stress-corrosion cracking. White iron formed in the weldment were found to decompose faster than white iron formed in the casting process, making it possible to take advantage of a production heat-treatment as a concurrent post-weld heat treatment. The technical and economical feasibility of automated iron casting welding was also discussed and was considered to be eminent due to the introdution of flux- cored electrodes, submerged are welding with specific flux additions, and other improvements in conventional technologies.

전위된 상악 견치 및 하악 측절치의 치험례

권해숙,현홍근,김영재,김정욱,장기택,김종철,한세현,이상훈 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.4

Tooth transposition is an anomaly of eruption characterized by the interchanged positions of two adjacent teeth, which is divided into complete and incomplete transposition. There are three common approaches for treating transposition: aligning the involved teeth in their transposed positions, moving them to their correct anatomic position in the arch and extracting one of the transposed teeth. Considerations in treatment plans are esthetic, function, risk of jeopardizing the roots and damaging the supporting structures, position of the root apex, developmental stages of teeth and expected compliance. The presented case reports described one maxillary canine-the first premolar transposition and two mandibular lateral incisor-canine transpositions. The former transposed teeth were arranged in their transposed position, and the latter transposed teeth were rearranged into their normal position. 치아전위란 인접한 두 치아의 위치가 서로 바뀐 치아 위치 이상을 말하며, 치관과 치근의 위치에 따라 완전전위와 불완전전위로 나눌 수 있다. 하악보다는 상악에 편측성으로 호발하며, 특히 상악 견치에서 자주 발생한다. 전위는 발견 시기와 전위된 양상에 따라 치료방법이 달라질 수 있다. 본 증례는 상악 견치와 제1소구치 간의 전위가 일어난 10세 7개월의 환아와 하악 측절치와 견치 간의 전위가 일어난 8세 11개월 환아와 8세 9개월 환아의 교정치료에 대한 것으로 양호한 치료 결과를 얻었고, 증례 별로 치료방법의 차이점에 관한 고찰을 하였기에 이를 보고하는 바이다.

접종능이 우수하고 페이딩 속도가 느린 구상 흑연 주철용 접종제 개발

권해욱,안종헌,최훈영 嶺南大學校 工業技術硏究所 2003 工業技術硏究所論文集 Vol.31 No.1

The performance of inoculant for ductile cast iron was investigated. The ability and fading rate of inoculant were evaluated through thermal analysis during holding the cast iron melt after the nodularizer and inoculant had been added. The effect of the addition of minor elements was also examined.

유치 수복물에 따른 주변 법랑질의 탈회 저항성 : QLF를 이용한 연구

권해숙,현홍근,김영재,김정욱,장기택,김종철,한세현,이상훈 大韓小兒齒科學會 2010 大韓小兒齒科學會誌 Vol.37 No.1

본 연구에서는 유치 수복물의 불소 방출 여부에 따른 주변 법랑질의 탈회 저항성과 재광화 효과를 살펴보고자 하였다. 건전 유전치 48개를 16개씩 임의로 세 군으로 나누어, FiltekTM Z250(1군), F2000(2군), KetacTM N100(3군)을 사용하여 제조사의 지시에 따라 충전하였다. 3일 동안 인공 우식 병소를 유발한 후, 14일 동안 인공 타액에 담가 재광화를 유발하였다. Quantitative light-induced fluorescence(QLF)를 이용하여 실험 단계와 시간에 따른 무기질 소실량(ΔQ)의 변화를 관찰한 결과는 다음과 같다. 1. 탈회가 일어난 인공 우식 병소의 ΔQ 값은 3군, 2군, 1군 순으로 작게 나타났고, 이 중 3군은 1군에 비해 유의한 탈회 저항성을 보였다. 2. 1군, 2군, 3군 모두 재광화 1일 후부터 초기 인공 우식 병소의 ΔQ 값과 비교 시 유의한 차를 보였으며, 관찰 기간 동안 지속적인 증가 양상을 나타내었다. 3. 재광화 속도를 의미하는 Δ(ΔQ)/일 값은 각 군에서 처음 1일 동안 유의성 있게 크게 나타났으며, 그 이후 급속히 감소하였다. 4. 수복 재료에 따른 재광화 정도는 각 군 간에 유의한 차이가 없었다. The objective of this in vitro study was to detect and monitor demineralization and remineralization of primary teeth according to restorative materials using quantitative light-induced fluorescence (QLF). A single bur hole was drilled on the each sound forty eight primary anterior teeth, and the specimens were divided into three groups. The cavity was restored with FiltekTM Z250(Group 1), F2000(Group 2), KetacTM N100(Group 3) following the manufacturer's instructions. The teeth were subjected to the demineralizing buffer for 3 days, and then subjected to a remineralizing buffer for 14 days. The change of mineral loss(ΔQ) according to the stages was evaluated by QLF and the following results were obtained: 1. When demineralization was done, ΔQ was increased as follows. : Group 1 (-110.79 ± 27.77) < Group 2 (-104.84 ± 28.95) < Group 3 (-90.16 ± 21.87) : Resistance to demineralization was statistically significant in Group 3. 2. There was a statistically significant increase in ΔQ of all groups since 1st day of remineralization 3. The rate of remineralization, Δ(ΔQ)/day, showed significant high value in each group on the 1st day then decreased rapidly. 4. There was no statistically significant difference in the degree of remineralization among restorative materials.

주철의 미세조직 결함과 그 원인

권해욱 한국주조공학회 2002 한국주조공학회지 Vol.22 No.4

투과전자현미경 투영상의 크기 분포로부터 입자 크기의 공간분포의 결정

권해욱 嶺南大學校 工業技術硏究所 1991 연구보고 Vol.19 No.1

An iterative method to determine the spatial size distribution of particles with simple polyhedral shapes from their projected images using extraction replicas has been developed. This method was applied to the size distributions of rod-shaped AIN particles and indicated that the lognormal distribution function described the spectral size distribution better than it did the distribution function of projected images.