악관절 수술후 안면신경 손상에 대한 임상적 연구

주재동,이의웅,김준배,박광호,김형곤 大韓顎顔面成形再建外科學會 1994 Maxillofacial Plastic Reconstructive Surgery Vol.16 No.4

Authors have studied retrospectively the facial nerve injury after TMJ surgery through the preauricular approach routine. The study material used was 4 patients of all 113 patients who were diagnosed as internal derangement and have been operated from March 1989 to February 1991 in Youngdong severance hospital, and were induced postoperatived facial nerve injury. The patient group who had the postoperative injured facial nerve was recognized degree of injury using the diagnostic method, Electromyography(EMG) and Nerve conduction test(NCT) which are used widely at present and was treated as conservative care and we identified the recovery time as the same method. The results as follows : 1. The meticulous care and precious surgical technique are needed in both operation and postoperation. During the TMJ surgery, the excessive retraction of the flap and frequent use of nerve stimulator and electric surgical knife should be avoided as possible and postoperative hematoma and swelling should be minimized. 2. The 4 patients were experienced with the postoperative facial nerve injury of all 133 patients who had been operated the TMJ surgery through the routine preauricular approach on our hospital. And the incidence of postoperative facial nerve injury happened was about 0.3% and its incidence was relatively low comparing with any other previous reports. 3. EMG and NCT were considered as useful methods which can diagnose the nerve injury objectively and identified the effect of treatment and recovery time. 4. The faical nerve-injured patients who were induced postoperatively after TMJ surgery, were diagnosed as second-degree nere injury through the EMG and NCT. And the patient group was treated well as conservative physical therapy for about 2 to 4 months.

Effect of μ-precipitates on the microstructure and mechanical properties of non-equiatomic CoCrFeNiMo medium-entropy alloys

Bae, Jae Wung,Park, Jeong Min,Moon, Jongun,Choi, Won Mi,Lee, Byeong-Joo,Kim, Hyoung Seop Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.781 No.-

<P><B>Abstract</B></P> <P>Non-equiatomic Co<SUB>17.5</SUB>Cr<SUB>12.5</SUB>Fe<SUB>55</SUB>Ni<SUB>10</SUB>Mo<SUB>5</SUB> (Mo5) and Co<SUB>18</SUB>Cr<SUB>12.5</SUB>Fe<SUB>55</SUB>Ni<SUB>7</SUB>Mo<SUB>7.5</SUB> (Mo7.5) medium-entropy alloys were synthesized by vacuum induction melting, cold rolling, and subsequent annealing treatment at various temperatures (900–1200 °C) and they were investigated to exploit the precipitation strengthening in addition to solid solution strengthening of alloys. The effect of annealing temperature and Mo content on the microstructure and mechanical properties are systematically analyzed. From the microstructural analysis, a Mo-rich μ phase is observed in the face-centered cubic (fcc) matrix. Increasing the Mo content and low annealing temperature enhance the formation of μ phase, which is consistent with the thermodynamic calculation results. The formation of μ phase effectively enhances the strength of the Mo7.5 alloy by precipitation strengthening, and suppression of grain growth and recrystallization by Zener pinning effect. These lead to superior combination of tensile strength as high as 1100 MPa and large ductility. Our results provide insights not only into μ-phase strengthening of fcc-structured alloys, but also into the future development of high-performance MEAs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of μ-precipitates in the non-equiatomic CoCrFeNiMo alloys is discussed. </LI> <LI> Further addition of Mo and decrease in annealing temperature enhances the formation of μ phase. </LI> <LI> Formation of μ phase retards the recrystallization and grain growth by Zener pinning effect. </LI> <LI> The present non-equiatomic CoCrFeNiMo alloys exhibits superior tensile properties by multiple strengthening mechanisms. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Trade-off between tensile property and formability by partial recrystallization of CrMnFeCoNi high-entropy alloy

Bae, Jae Wung,Moon, Jongun,Jang, Min Ji,Yim, Dami,Kim, Daeyong,Lee, Sunghak,Kim, Hyoung Seop Elsevier 2017 Materials science & engineering. properties, micro Vol.703 No.-

<P><B>Abstract</B></P> <P>In this work, a high-entropy alloy of equiatomic CrMnFeCoNi was processed by vacuum induction melting followed by rolling. After cold rolling, annealing for one hour was conducted during which the annealing temperature was varied from 650 to 1000°C. This was done to investigate the effect of microstructure on tensile properties and stretch formability (defined as the capability of materials to undergo plastic deformation under biaxial stretching). The strengthening effect of partial recrystallization, with a remaining small fraction of sigma phase particles, led to improved yield and tensile strengths while minimizing the loss of ductility. Fully recrystallized microstructure resulted in a slight increase in ductility, and a considerable decrease in strength, during a tensile test. On the other hand, the results for stretch formability suggest that partial recrystallization had exactly the opposite results. In this regard, the present results raise a new issue to consider when utilizing partial recrystallization for improvement of mechanical properties.</P>

Exceptional phase-transformation strengthening of ferrous medium-entropy alloys at cryogenic temperatures

Bae, Jae Wung,Seol, Jae Bok,Moon, Jongun,Sohn, Seok Su,Jang, Min Ji,Um, Ho Yong,Lee, Byeong-Joo,Kim, Hyoung Seop Elsevier 2018 Acta materialia Vol.161 No.-

<P><B>Abstract</B></P> <P>High-entropy alloys (HEAs) are a newly emerging class of materials that show attractive mechanical properties for structural applications. Particularly, face-centered cubic (fcc) structured HEAs and medium-entropy alloys (MEAs) such as FeMnCoNiCr and CoNiCr alloys, respectively, which exhibit superior fracture toughness and tensile properties at liquid nitrogen temperature, are the potential HEA materials available for cryogenic applications. Here, we report a ferrous Fe<SUB>60</SUB>Co<SUB>15</SUB>Ni<SUB>15</SUB>Cr<SUB>10</SUB> (at%) MEA exhibiting combination of cryogenic tensile strength of ∼1.5 GPa and ductility of ∼87% due to the multiple-stage strain hardening. Astonishingly, detailed microstructural observations at each stage reveal the sequential operation of deformation-induced phase transformation from parent fcc to newly formed bcc (body-centered cubic) phases. No compositional heterogeneity is observed at phase boundaries, indicating diffusionless phase transformation, as confirmed by atom probe tomography. The transformation to bcc phase occurs predominantly along grain boundaries (GBs) at the early stage of plastic deformation. Simultaneously, numerous deformation-induced shear bands (SBs) having stacking faults associated to the Shockley partial dislocations and thin hcp plates, form within fcc grains. Further deformation leads to the intense nucleation and growth of the bcc phase at the intersections of SBs within fcc grains. These micro-processes consecutively enhance the strain hardening rate, which play a key role in the multiple strain hardening behavior. The in-situ neutron diffraction studies make it clear that the martensite formation and the concurrent load partitioning between the fcc and bcc phases play an important role in the increase in strength. Furthermore, replacing high-cost alloying elements cobalt and nickel with iron, as well as introduction of metastability-engineering at liquid nitrogen temperature, distinguishes the new ferrous MEAs from previously reported equiatomic HEAs. This result underlines insights to provide expanded opportunities for the future development of HEAs for cryogenic applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

<i>In situ</i> neutron diffraction study of phase stress evolution in a ferrous medium-entropy alloy under low-temperature tensile loading

Bae, Jae Wung,Kim, Jung Gi,Park, Jeong Min,Woo, Wanchuck,Harjo, Stefanus,Kim, Hyoung Seop Elsevier 2019 Scripta materialia Vol.165 No.-

<P><B>Abstract</B></P> <P>Phase stress evolution of face-centered cubic (FCC) and deformation-induced body-centered cubic (BCC) phases was measured in recently developed ferrous medium-entropy alloy. This was done during tensile deformation at −137 °C using <I>in situ</I> neutron diffraction measurement for the quantitative interpretation of the role of martensitic transformation on the improved low-temperature tensile properties. The strain-hardening rate curve exhibits two-stage hardening behavior, and the phase stress and stress contribution from the BCC phase increases significantly while that from FCC phase decreases during plastic deformation. This is a direct demonstration that BCC phase contributes significantly to the increase in strength and strain hardening.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

유방암에서 p53유전자변이의 염기서열분석

배정원,이은숙,조민영,구범환,황정웅,김인선,박설희,이민재 고려대학교 의과대학 1998 고려대 의대 잡지 Vol.35 No.2

Breast cancer presents the third common malignancy in Korean women. The etiology of breast cancer involves very complex factors such as genetic, hormonal, and dietary. The peak age of Korean women's breast cancer is more earlier, about ten years, than western women. Extensive genetic analysis of breast cancer have been done trying to correlate these genetic alterations with the disease. p53 gene is a tumor suppressor gene. Mutations eliminating or altering the p53 protein function are the single most common genetic alteration in nearly all types of human cancers. The product of the p53 gene is hypothesized to maintain genomic stability by blocking cell replication or by initiating apoptosis after DNA damage. This study investigated to determine p53 gene mutations detected at the DNA level. Abnormalities of the p53 genes were examined in 27 primary freshed breast cancer tissues. Mutations in p53 exons 5-7 were identified in 2 of 27 cases(7%) using a polymerase chain reaction-single strand conformational polymorphism(PCR-SSCP) analysis: one is frameshift mutation which is the addition of c(gcc→Cgcc) at codon 159, exon 5, the other is missense mutation which substitutes tcc to tGc at codon 241, exon 7. In conclusion, mutant biology of p53 gene in Korean women's breast cancer is missense and frameshift. It is necessary to perform further study in mutation of other exons 2, 8, 9, and 11 of p53 gene.

Boron doped ultrastrong and ductile high-entropy alloys

Seol, Jae Bok,Bae, Jae Wung,Li, Zhiming,Chan Han, Jong,Kim, Jung Gi,Raabe, Dierk,Kim, Hyoung Seop Elsevier 2018 Acta materialia Vol.151 No.-

<P><B>Abstract</B></P> <P>A new class of materials called high-entropy alloys (HEAs) constitutes multiple principal elements in similar compositional fractions. The equiatomic Fe<SUB>20</SUB>Mn<SUB>20</SUB>Cr<SUB>20</SUB>Co<SUB>20</SUB>Ni<SUB>20</SUB> (at%) HEA shows attractive mechanical properties, particularly under cryogenic conditions. Yet, it lacks sufficient yield and ultimate tensile strengths at room temperature. To strengthen these materials, various strategies have been proposed mainly by tuning the composition of the bulk material while no efforts have been made to decorate and strengthen the grain boundaries. Here, we introduce a new HEA design approach that is based on compositionally conditioning the grain boundaries instead of the bulk. We found that as little as 30 ppm of boron doping in single-phase HEAs, more specific in an equiatomic FeMnCrCoNi and in a non-equiatomic Fe<SUB>40</SUB>Mn<SUB>40</SUB>Cr<SUB>10</SUB>Co<SUB>10</SUB> (at%), improves dramatically their mechanical properties, increasing their yield strength by more than 100% and ultimate tensile strength by ∼40% at comparable or even better ductility. Boron decorates the grain boundaries and acts twofold, through interface strengthening and grain size reduction. These effects enhance grain boundary cohesion and retard capillary driven grain coarsening, thereby qualifying boron-induced grain boundary engineering as an ideal strategy for the development of advanced HEAs.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

서울시 노원구 일원의 자동판매기에서 판매되는 커피와 율무차의 온도와 pH 및 미생물 총균수

이재준,김태현,이종필,임관헌,송원경,김제중,정석진,배현웅,이영현 서울産業大學校 1998 논문집 Vol.47 No.1

서울시 노원구 일원의 공공 장소에 설치된 10곳의 자동 판매기에서 판매되는 밀크커피와 율무차의 온도와 pH 그리고 미생물 총균수를 계절별 (하절기 및 동절기)지역별로 조사하였다. 자판기에 표시된 온도 범위는 90∼96℃였지만 밀크커피와 율무차의 실제 온도 범위는 각각 63.1∼71.5℃과 65.9∼72.7℃ 그리고 동절기 62.8∼70.9와 64.5∼71.5℃였다. 계절에 따라 밀크커피의 온도차이가 존재하지 않았지만 율무차의 온도차이는 존재하였다. 밀크커피와 율무차의 온도는 자판기별로 차이가 있었다(P<0.01). 밀크커피와 율무차의 pH 범위는 하절기에는 각각 6.04∼6.57과 6.76∼7.01 그리고 동절기에는 각각 6.10∼6.86과 6.59∼7.16이었다. 계절에 따라 밀크커피와 율무차의 pH는 각각 존재하였다(P<0.01), 밀크커피와 율무차의 pH는 자판기별로 차이가 났다 (P<0.01). 밀크커피는 1㎤당 하절기 미생물 총균수(CFU, colony forming units)는 10 곳 중 8곳에서는 전혀 나타나지 않았거나 10미만 이였으며, 동절기에는 전혀 나타나지 않거나 10미만 이었다. 미생물 총균수가 많은 2곳의 log CFU/㎤는 2.90과 2.79였다. 율무차 1㎤ 당 log 미생물 총균수의 범위는 1.32∼3.44와 0.59∼2.51였으며 지역별로 차이를 나타냈다(P<0.01). 하지만 진균과 대장균은 검사한 어느 시료에서도 검출되지 않았다. 율무차의 미생물 총균수, pH, 온도간의 상호 상관관계를 분석한 결과, 동절기에는 율무차의 미생물 총균수와 온도간에 유의한 음의 상관관계를 분석한 결과, 동절기에는 율무차의 미생물 총균수와 온도간에 유의한 음의 상관관계(r=-173)를 갖고 있다(P<0.01), 그러나 율무차의 미생물 총균수 대 온도와 pH간의 중회귀분석을 한 결과 유의한 관계가 존재하지 않았다. The variation of temperature, pH, and microbial content of coffee and adlay drinks from 10 vending machines in Nowon-gu, Seoul were investigated. The temperature of coffee and adlay drinks ranged from 63.1 to 72.3℃ and from 65.9 to 72.7℃, respectively, though the water temperatures in the vending machines were shown between 90 and 96℃. The temperature of coffee and adlay drinks were significantly different depending on the location (P<0.01). The pH range of coffee and adlay drinks were 6.04~6.57 and 6.76~7.01. respectively with showing significant differenence depending on the location (P<0.01). Total plate counts (CFU, colony forming units) of coffee per 1 ㎤ were zero or less than 10 in eight locations out of ten. The log CFU/㎤ for rest of two were 2.90 and 2.79. The log CFU/㎤ of adlay drinks ranged from 1.32 to 3.44 and were significantly different depending on the location of the vending machines )P<0.05).Fungus and E . coli, were not detected in all samples tested. There was no significant ultiple correlation between total plate counts versus temperature and pH of adlay drinks.

Ultra-high tensile strength nanocrystalline CoCrNi equi-atomic medium entropy alloy processed by high-pressure torsion

Praveen, S.,Bae, Jae Wung,Asghari-Rad, Peyman,Park, Jeong Min,Kim, Hyoung Seop Elsevier 2018 Materials science & engineering. properties, micro Vol.735 No.-

<P><B>Abstract</B></P> <P>A nanocrystalline CoCrNi alloy of ~50 nm grain size with the ultra-high ultimate tensile strength of ~2.2 GPa and fracture strain of ~9% was fabricated using high-pressure torsion. The presence of high density of nano-twins, stacking faults, dislocations, and nano-grains is attributed to the superior mechanical properties.</P>

슬러리환원법에 의한 MLCC용 미세 니켈 분말 직접 제조

신기웅 ( Gi Wung Shin ),안종관 ( Jong Gwan Ahn ),김동진 ( Dong Jin Kim ),김상배 ( Sang Bae Kim ),안재우 ( Jae Woo Ahn ) 한국광물학회 2010 광물과 암석 (J.Miner.Soc.Korea) Vol.23 No.3

고순도 니켈 금속염으로부터 미세하고 입도가 균일한 니켈 분말 직접 제조 연구를 수행하였다. 구형의 형상을 갖는 미세한 니켈 분말을 제조하기 위하여 입도제어가 가능한 슬러리환원법을 사용하였다. 제조된 니켈 분말에 화학성분, 입도, X선회절, 주사전자현미경 분석을 실시하여 니켈 분발의 특성을 조사하였다. 환원제로 하이드라진(hydrazine)을 사용하고, 4.5 M NaOH에서 90분 반응시켜 약100~200 nm의 입도를 가진 분산도가 양호한 구형의 니켈 분말을 제조할 수 있었다. Fine nickel metal powder of uniform morphology, narrow size distribution, and high purity was prepared from high purity metal solution. Slurry reduction method for the synthesis of metal powder was applied with a special interest in their fine and spherical shape. The products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Well dispersed ultrafine nickel powder with the particle size range of 100~200 nm was produced from Ni-hydrazine precursor using hydrazine as a reductant for 90 min reaction in 4.5 M NaOH solution.