고온 코팅용 Cr-Al합금의 미세조직 및 특성에 미치는 Si 첨가의 영향

김정민,김일현,김현길,Kim, Jeong-Min,Kim, Il-Hyun,Kim, Hyun-Gil 한국재료학회 2019 한국재료학회지 Vol.29 No.1

Cr-Al alloys are attracting attention as oxidation resistant coating materials for high temperature metallic materials due to their excellent high temperature stability. However, the mechanical properties and oxidation resistance of Cr-Al alloys can be further enhanced, and such attempts are made in this study. To improve the properties of Cr-Al alloys, Si is added up to 5 wt%. Casting specimens with different amounts of Si content are prepared by a vacuum arc remelting method and isothermally heated under steam conditions at $1,100^{\circ}C$ for 1 hour. The as-cast microstructure of low Si alloys is mainly composed of only a Cr phase, while $Al_8Cr_5$ and $Cr_3Si$ phases are also observed in the 5 % Si alloy. In the high Si alloy, only Cr and $Cr_3Si$ phases remain after the isothermal heating at $1,100^{\circ}C$. It is found that Si additions slightly decrease the oxidation resistance of the Cr-Al alloy. However, the microhardness of the Cr-Al alloy is observed to increase with an increasing Si content.

레이저 표면 용융공정으로 Al-Cr 코팅한 Zr합금의 미세조직 특성

김정민,이재철,김일현,김현길,Kim, Jeong-Min,Lee, Jae-Cheol,Kim, Il-Hyun,Kim, Hyun-Gil 한국재료학회 2017 한국재료학회지 Vol.27 No.10

In this study, the coating of an Al-Cr layer on the surface of a Zircaloy-4 alloy was carried out through plasma pretreatment coating and a laser surface melting process. Two different conditions for laser treatment, severe or minimal surface melting of the Zr alloy substrate, were applied to form the final coating. When there was significant surface melting of the Zr alloy, the solidification microstructure of the newly formed coating layer was mainly composed of needle-shaped $Al_3Zr$, Al(Cr) and $Al_7Cr$ phases. On the other hand, the solidification microstructure of the coating layer was mainly composed of Al(Cr) and $Al_7Cr$ phases when there was minimal surface melting of Zr base in the laser process. However, when the coating was maintained at $1100^{\circ}C$ for 2 hours, significant inter-diffusion occurred between the phases in the coating. As a result, the upper part of the coating layer was observed to mainly consist of $Al_3Zr$ and $Al_8Cr_5$ phases, regardless of the laser treatment conditions.

토픽 분할에 의한 토픽맵 매칭 및 통합 기법

김정민,정현숙,Kim, Jung-Min,Chung, Hyun-Sook 한국정보처리학회 2007 정보처리학회논문지D Vol.14 No.7

본 논문에서는 토픽맵의 모델 특성을 고려한 토픽맵 매칭 및 통합 기법을 제안한다. 이전까지의 대부분의 스키마 매칭 연구들은 계산 시간의 효율성을 고려하지 않고 매칭 기법의 범용성 및 정확성을 높이기 위한 목적으로 개발되어 왔다. 그러나 현재 표준적인 온톨로지 언어로 RDF/OWL과 토픽맵이 사용되고 있으며 앞으로 많은 온톨로지들이 이들 언어로 구현될 것이다. 따라서 본 논문에서는 토픽맵 데이터 모델의 구조적 특성 및 제약조건을 고려하여 토픽 분할, 토픽명기반 매칭연산, 속성기반 매칭연산, 계층구조기반 매칭연산, 연관관계기반 매칭연산 및 통합 알고리즘을 개발함으로써 효과적이면서 효율적인 토픽맵 매칭 및 통합이 가능함을 보인다. In this paper, we propose a topic maps matching and merging approach based on the syntactic or semantic characteristics and constraints of the topic maps. Previous schema matching approaches have been developed to enhance effectiveness and generality of matching techniques. However they are inefficient because the approaches should transform input ontologies into graphs and take into account all the nodes and edges of the graphs, which ended up requiring a great amount of processing time. Now, standard languages for developing ontologies are RDF/OWL and Topic Maps. In this paper, we propose an enhanced version of matching and merging technique based on topic partitioning, several matching operations and merging conflict detection.

외모에 대한 사회문화적 요인, 신체질량지수 및 자아존중감이 신체상에 미치는 영향 - 발달단계별 차이를 중심으로 -

김정민,이세진,Kim, Jung-Min,Yi, Se-Jin 한국가정관리학회 2009 가정과삶의질연구 Vol.27 No.6

The purpose of the study is to investigate developmental changes in the effect of sociocultural factors towards appearance, body mass index and self-esteem on body image. Participants were 315elementary school, 305middle school students, 310hight school students and 346college students from Seoul and Gyeonggi Province. Collected data were analyzed through Cronbach's $\alpha$, Two-way ANOVA, Pearson's correlation, and stepwise multiple regression. The findings of the study were as follows: 1) Sociocultural factors towards appearance, body mass index, self-esteem and body image differed by grade and gender. 2) Peers, self-esteem, BMI and mass media were significant predictors of elementary school students' body image. Mass media, BMI and self-esteem were significant predictors of middle school students' body image. Self-esteem, peers, BMI, gender and mass media were significant predictors of high school students' body image. Self-esteem, mass media and BMI were significant predictors of college students' body image.

전 상악골 절제술 후 양경 유리 견갑 골-피부 피판을 이용한 재건 3례

김정민,하범준,문구현,현원석,방사익,오갑성,Kim, Jung-Min,Ha, Bom-Jun,Mun, Goo-Hyoun,Hyun, Won-Sok,Bang, Sa-Ik,Oh, Kap-Sung 대한미세수술학회 2003 Archives of reconstructive microsurgery Vol.12 No.1

We used bipedicled scapular osteocutaneous free flap for total maxillectomy defect reconstruction in 3 cases of malignant maxillary tumor. We elevated two flaps of the skin paddle and the bone flap with one common pedicle - the subscapular artery - which was devided to the angular branch of the thoracodorsal artery and the circumflex scapular artery to reconstruct the nasal cavity, the palate and the zygoma. The angle between the two flaps was free enough so that we could transfer the two flaps through a single microanastomosis. After the operation, patients could swallow and pronounce well, and the wound contracture was minimal so that we could get aesthetically good result.

내산화성 Cr-Si-Al합금의 주조상태 및 고온가열 후의 미세조직 특성

김정민,김채영,양원철,박준식,Kim, Jeong-Min,Kim, Chae-Young,Yang, Won-Chul,Park, Joon-Sik 한국재료학회 2021 한국재료학회지 Vol.31 No.3

Cr-Si based alloys are not only excellent in corrosion resistance at high temperatures, but also have good wear resistance due to the formation of Cr3Si phase, therefore they are promising as metallic coating materials. Aluminum is often added to Cr-Si alloys to improve the oxidation resistance through which stable alumina surface film is formed. On the other hand, due to the addition of aluminum, various Al-containing phases may be formed and may negatively affect the heat resistance of the Cr-Si-Al alloys, so detailed investigation is required. In this study, two Cr-Si-Al alloys (high-Si & high-Al) were prepared in the form of cast ingots through a vacuum arc melting process and the microstructural changes after high temperature heating process were investigated. In the case of the cast high-Si alloy, a considerable amount of Cr3Si phase was formed, and its hardness was significantly higher than that of the cast high-Al alloy. Also, Al-rich phases (with the high Al/Cr ratio) were not found much compared to the high-Al alloy. Meanwhile, it was observed that the amount of the Al-rich phases reduced by the annealing heat treatment for both alloys. In the case of the high temperature heating at 1,400 ℃, no significant microstructural change was observed in the high Si alloy, but a little more coarse and segregated AlCr phases were found in the high Al alloy compared to the cast state.

측두하악장애를 가진 성인여성에 있어 중절치부 최대교합력 유지양상

김정민,신금백,Kim, Chung Min,Shin, Geum Baek 대한안면통증구강내과학회 1987 Journal of Oral Medicine and Pain Vol.12 No.1

In order to evaluate the effect of signs and symptoms of temporomandibular disorders on the bite force of anterior teeth, the author estimated a feature of maintaining the maximum bite force on central incisors in Korean 34 adult females with signs and symptoms of temporomandibular disorders (TMD group) and in Korean 31 adult females within normal masticatory function far from any sign or symptom of TMD (control group), and analyzed the data statistically. The obtained results were as follows: 1. There was not a significant difference of the maximum bite force on central incisors between TMD group and control group (P>0.05). 2. The duration of maintaining the maximum bite force on central incisors in TMD group was shorter than it in control group (P<0.01).

디지털화상의 기본특성

김정민,Kim, Jeong-Min 대한디지털의료영상학회 2005 대한디지털의료영상학회논문지 Vol.7 No.1

$bla_{SHV-2a}$와 $bla_{SHV-12}$ 항균제 내성 유전자의 분자적 진화 및 확산에 IS26 Mobile Element의 개입

김정민,신행섭,조동택,Kim, Jung-Min,Shin, Haeng-Seop,Cho, Dong-Taek 대한미생물학회 2000 大韓微生物學會誌 Vol.35 No.3

A clinical isolate of Klebsiella pneumoniae K7746 produced the extended-spectrum ${\beta}$-lactamase (ESBL) SHV-12. A 6.6 kb BamHI fragment containing the $bla_{SHV-12}$ gene of K7746 strain was cloned into pCRScriptCAM vector resulting in the recombinant plasmid p7746-Cl. The restriction map of 3.6 kb inserted DNA and sequences immediately surrounding $bla_{SHV-12}$ of p7746-C1 were homologous to plasmid pMPA2a carrying $bla_{SHV-2a}$. In addition, both $bla_{SHV-12}$ and $bla_{SHV-2a}$ were expressed from a common hybrid promoter made of the -35 region derived from the left inverted repeat of IS26 and the -10 region from the $bla_{SHV}$ promoter itself. The results indicate that $bla_{SHV-12}$ and $bla_{SHV-2a}$ may have evolved from a common ancestor in the sequential order of $bla_{SHV-2a}$ first, followed by $bla_{SHV-12}$. Furthermore, by the PCR mapping method using primers corresponding to the IS26 and $bla_{SHV}$, the association between IS26 and $bla_{SHV}$ was studied in 12 clinical isolates carrying $bla_{SHV-2a}$, 27 clinical isolates carrying $bla_{SHV-12}$, and 5 reference strains carrying $bla_{SHV-1}$ to $bla_{SHV-5}$. All 39 strains carrying $bla_{SHV-2a}$ or $bla_{SHV-12}$ were positive by the PCR, providing confirmative evidence that IS26 has been involved in the evolution and dissemination of $bla_{SHV-2a}$ and $bla_{SHV-12}$. But 5 reference strains carrying $bla_{SHV-1}$ to $bla_{SHV-5}$ were negative by the PCR. Therefore, we concluded that the molecular evolutionary pathway of $bla_{SHV-2a}$ and $bla_{SHV-12}$ may be different from that of other $bla_{SHV-ESBL}$, e.g., $bla_{SHV-2}$, $bla_{SHV-3}$, $bla_{SHV-4}$, and $bla_{SHV-5}$.

건축건설공사의 공종별 위험도와 직무스트레스의 상관관계

김정민,이종빈,장성록,Kim, Jeongmin,Lee, Jong-Bin,Chang, Seong Rok 한국안전학회 2017 한국안전학회지 Vol.32 No.4

In this study, the risk level of architectural works was calculated by applying work period and number of input workers based on accidents records from 2012 to 2014 and the architectural works were divided into four groups(High-High, High-Low, Low-High, Low-Low) according to risk levels of fatal accidents and loss time accidents. And then questionnaire on the job stress level of workers was performed for 670 workers working in the architectural work using Korean Occupational Stress Questionnaire Form developed by KOSHA. And then the relationship between the risk level and job stress level of four groups was analyzed. Results showed that 1) risk levels of fatal and loss time accidents applied by work period and input workers were analyzed to be different with those of previous research based on the number of fatal and loss time accidents; 2) job stress level of workers has been analyzed to have a significant relationship with the risk level of fatal and loss time accident; 3) specially, the average of job stress level of 'HH(High-High)' group was higher than those of other groups; 4) among the subfactors of job stress, interpersonal conflict, job insecurity, organizational system and lack of reward were analyzed to be key factors to affect the risk level.