Influence of Phase Composition in TiAlSiN Hard Coatings on the Evolution of Structure and Mechanical Properties

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

The aim of this study is to investigate the structural evolution and mechanical properties of TiAlSiN coatings when processedby the arc ion plating method. To form a hard coating, Ti, Al, and Si powders were mechanically alloyed by planetary ballmilling; the powders were then densely compacted during a rapid sintering process into a ternary system coating, i.e. TiAlSi. The evolution of the structural phase from a powder to a compact material is dominated considerably by phase states suchas a supersaturated solid solution or intermetallic compounds. In the case of coating layers, the factors that determine thestructural evolution are associated with the phase stability of the nano-crystalline structure that in turn is associated withthe Ti/Al composition ratio. Motivated by this, we performed experiments to investigate the distribution of microstructures;the material’s binding energy, quantitative properties, transformation of crystal structure, and distribution of amorphous/crystalline were all recorded. In particular, the relationship between the physical and chemical properties during the coatingprocess is considered to be the dominant factor controlling the orientation and morphology of that zone (1, T, and 2). TheTiAlSiN coating layer was found to have hardness above 45 GPa and an adhesion above 100 N. In other words, understandingthe evolution and structure of TiAlSin helped us to produce a material with excellent properties that can be used as a hardcoating. Specifically, these properties were induced by a grain refinement of the nano-crystalline structure that correspondsto an increase in the silicon nitride contents.

반응표면 분석을 이용한 Salmonella enteritidis의 증식 효능 평가

홍정미,정효준,이홍근 한국환경과학회 2002 한국환경과학회지 Vol.11 No.12

This stidy was performed to investigate the single and combined effect of concentrations of garlic juice according to the pH and temperature on the growth of Salmonella enteritdis in brain heart infusion broth, and to develope Response surface model for the effect of concentrations of garlic extract. The results of electric conductibility of Salmonella enteritidis growing in the range of incubation temperature (25~42℃), PH(5.5~9.0) and concentration of garlic juice(0~0.8%) showed that a badge with high low D.T.value and concentration of garlic extract were significantly with D.T.value and concentration of garlic extract were significantly correlated with D.T.value (p<0.01). Growth of Salmonella enteritidis in the condition of 37℃ and pH7.0 presented the lowest D.T.value.

에어컨 냉각 팬용 브러쉬레스 DC 전동기의 역기전력 분석에 대한 연구

조정현,김지현,정정원,황흥식,이치우 경성대학교 공학기술연구소 2012 공학기술연구지 Vol.18 No.-

Compared to conventional dc motors having the combination of commutators and brushes, a brushless DC (BLDC) motor is one of the highly efficient motors due to its electrical commutation without a brush, and this feature allows the BLDC otor to be more suitable for an application requiring no maintenance due to mechanical wear between a commutator and a brush. Also, the BLDC motor has a few benefits over both a dc motor and an induction motor such as high dynamic response, high efficiency, logn life span, and low noise in wide speed-torque region. This paper investigates the variation of voltage induced in phase windings in a BLDC motor in several cases with respect to stack length, steel grade, and coil material. This study is numerically conducted and it is verified from the theoritical point of view by comparing the result of simulation with that of experimental measurement.

Effect of Mechanical Alloying on the Microstructural Evolution of Al60Cr30Si10 Alloys Processed by Spark Plasma Sintering

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

In this study, Al, Cr and Si fine powders were alloyed by planetary ball milling to investigate their microstructural evolution,following their mechanical alloying behavior. The formation of Al(Cr) supersaturated solid solution by the Cr grainsembedded in Al-matrix, which contributed substitutional structure is discussed in relation to their structural evolution inaccordance with the distortion of a crystal lattice. The compacts of Al–Cr–Si alloys were prepared by rapid sintering withina short time by dense consolidation above the density of 99.9% as the formation of intermetallics, except in the case of thedistribution of single-phases induced by the Al-melting. The formation behavior of intermetallics was dominated by dependenceon the structures of the milled-powder and subsequent sintering temperature. To estimate the consolidated behaviorsof compacts, various approaches derived from TEM and XRD analysis were taken to obtain microstructural evidences ofthe inter-diffusion, following the presence of thermally stable intermetallics.

Rapid Consolidation of WC‑ZrSiO4 Hard Materials by Spark Plasma Sintering: Microstructure, Densification, and Mechanical Properties

Jeong‑Han Lee,Ik‑Hyun Oh,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

Densely consolidated WC-based hard materials with 5–20 vol% ZrSiO4was fabricated by spark plasma sintering at 1400 ℃ ata constant heating rate of 70 ℃/min−1. To achieve mechanical alloying of WC-ZrSiO4, planetary ball milling was carried outfor 12 h, during which the brittle-brittle components (WC-ZrSiO4) became fragmented and their particles became refined. Itwas observed that certain, specific, non-isothermal sintering kinetics, such as apparent activation energy, sintering exponents,and densification strain, affected the densification behavior. The evolution of phase structure from powder to compact wasfound to be related the lattice distortion and micro-strain in the basal planes of WC. By examining the mechanical propertiesof the samples, it was that the added zircon content leads to enhanced fracture toughness (12.9 MPa m1/2) owing to thepresence of WC-ZrSiO4 in the cemented carbide. In fact, the microcrack propagation of the fracture passed through zirconfrom a transgranular to a ductile component (fcc) where the crack tips could be absorbed.

서울의 Penicillinase Producing Neisseria gonorrhoeae 발생빈도(1998)

김재홍,김준호,반재용,이정우,황성주,정준규,정성태,강진문,조흔정,홍창의,정혜신,이한승,김이선,이봉길,이종호,선영우,한기덕,윤성필,이성훈,안종성,박석범,문승현,조항래,김형섭,류지호,황재영,박준홍,손상욱 한양대학교 의과대학 2001 한양의대 학술지 Vol.21 No.1

In recent years, gonorrhea has been pandemic and remains one of the most common STDs in the world, especially in developing countries. For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria gonorrhoeae(PPNG), we have been trying to study the patients who have visited the Venereal Disease Clinic of Choong-Ku Public Health Center in Seoul since 1980 by menas of the chromogenic cephalosporin method. In 1998, 93 strians of N. genorrhoeae were isolated, among which 60(64.5%) were PPNG. The prevalence of PPNG in Seoul, which had been decreased to 39% in 1996 after a peak of 74.3% in 1993, is increased to 64.5% in 1998.

IT 기술력으로 대한민국을 연결하다: 메쉬코리아의 성공 메커니즘 분석

유정범(Jeong-bum Rhyu),박재홍(Jae-hong Park),이동근(Dong-gun Lee),박기찬(Kichan Park) 한국경영학회 2021 Korea Business Review Vol.25 No.신년 특별호

온라인 쇼핑 시장의 발전과 코로나19 바이러스의 확산으로 비대면 생활 시대가 점진되면서 라스트 마일 시장(Last Mile Market)은 유래 없는 호황을 맞이하고 있다. 이제는 배송의 대상이 음식에 국한되지 않고 편의점, H&B 스토어 등 비(非)음식분야까지 서비스가 보편화 되었다. 본 연구는 라스트 마일 업계에서 IT(Information Technology) 기술력을 기반으로 성공적인 성장을 거듭하고 있는 메쉬코리아의 성공 사례를 자원기반이론(RBV)의 확장 모델로 평가되는 SER-M 패러다임을 통해 분석했다. 주체의 특성, 환경적 조건, 자원의 역량요인 등이 융합 · 결합을 통해 어떠한 메커니즘을 형성하여 성공할 수 있었는지, 그리고 더 큰 성장을 위해 어떤 도전과제에 직면하고 있는지를 살펴보았다. 분석결과, 선순환적 성장 메커니즘을 구축시켜준 주요 원동력은 다음과 같이 나타났다. 첫째, 주체변수의 특성은 창업가의 기업가정신으로 나타났다. 메쉬코리아의 창업주 유정범 대표는 아버지의 장례식장에서 배달 시스템의 비효율성을 보면서 이를 개선하기 위해 창업을 결심했다. 유대표의 기업가 정신은 현장 중시 철학인 ‘우문현답’, 모두에게 이익이 되도록 하려는 모토인 ‘세상에서 가장 깨끗한 1원의 가치’, 그리고 흔히 라이더(Rider)라 부르는 배송기사들에 대한 ‘섬김의 리더십’실천으로 부각된다. 둘째, 성공을 위한 환경적 요인은 온라인 쇼핑이 활성화되어 라스트 마일 사업이 확대된 시장 환경, 인공지능(AI), 빅데이터 등 다양한 기술의 발전에 힘입어 신유통 등 물류 시장에 혁신의 바람을 불게 한 시대적 환경, 그리고 코로나-19 신종 바이러스 확산에 따른 강력한 사회적 거리두기 조치등의 정책적 환경이 새로운 기회를 제공한 것으로 나타났다. 셋째, 유정범 대표의 기업가 정신과 코로나 팬데믹 환경에 더하여 메쉬코리아가 보유하고 있는 인적, 물적 자원을 업계에서 유일하게 직영 구조로 운영하는 전략적 자원으로 구축 및 활용함으로써 글로벌 배송 업체까지도 벤치마킹하고자 하는 메쉬코리아의 선순환적 성공 메커니즘이 사내외로 확산되고 있음을 확인하였다. 논문의 마지막 부분에서는 대부분의 사업과 산업이 어려움에 처한 상황에서도 배송업계에 대한 낙관적 전망에 따라 포화상태로 접어들고 있는 라스트 마일 업계에서 메쉬코리아가 향후 직면하게 될 도전과제에 대하여 살펴보았다. 본 연구는 메쉬코리아의 성공적 성장사례를 통해 스타트업 기업들의 시장진입 및 성장전략, 그리고 그 과정에서 직면하게 되는 이슈와 과제를 어떻게 대응하고 극복해 갈 것인지에 대한 방법을 토론하는 데 그 의미를 두고자 하였다. The Last Mile Market is experiencing an unprecedented boom due to advent of the non-faceto-face life era caused by the development of the online shoppong market and the spread of the COVID-19. The target of delivery is not limited to food, and services have become common in non-food fields such as convenience stores and H&B stores. This study analyzed the success cases of Mesh Korea, which has achieved successful results based on IT(Information Technology) in the Last Mile Industry, through a ser-M model. and this study examines what kind of mechanisms the subject, environment, and resourse factors could have formed and succeeded through fusion and combination, and what challenges they face for greater growth. CEO Rhyu Jeong-beom, founder of Mesh Korea, decided to start a business in order to improve the inefficiency of the delivery system at his father’s funeral. His entrepreneurship is “Woo Moon Hyeon-dap(The answer to our problem is in the field),” a philosophy that focuses on the field, “the cleanest value of 1 won in the world,” and the leadership of serving delivery riders. Environmental factors for success were analyzed by dividing in to Market Environment in which the Last Mile Market has expanded due to active online shopping, The environment of the times in which various technologies such as AI(artificial intelligence) and big data have been developed to blow the wind of innovation in the logistics market. and Policy Environment such as strong social distancing following the spread of the COVID-19. This study presents the challenges that Mesh Korea will face in the future in the last mile industry, which is saturated with indyustry optimism. And it is meaningful in discussing how to overcome the start-up and growth of start-up companies and the challenges they will face through the case of Mesh Korea.

교육과정 개정에 따른 과학의 본성 수준 및 반영 정도 분석 : 2009 개정 교육과정과 2015 개정 교육과정 사례 분석

정명현(Jeong, Myeonghyeon),유인성(You, Insung),민소원(Min, Sowon),홍훈기(Hong, Hun-Gi) 학습자중심교과교육학회 2020 학습자중심교과교육연구 Vol.20 No.17

지난 수십 년간 과학의 본성의 중요성은 지속적으로 강조되어왔다. 본 연구에서는 2009 개정 교육과정에서 2015 개정 교육과정으로 교육과정이 개정됨에 따라 과학의 본성 반영정도와 그 수준이 어떻게 변화되고 있는지 알아보았다. Abd-El-Khalick et al. (2008)의 과학의 본성 정의를 반영하여 구성된 이정원 외(2016)의 NOSAT(Nature of Science analyzing tool) 분석틀을 이용하여 2009 개정 교육과정융합과학 교과서와 2015 개정교육과정 통합과학 교과서의 과학의 본성의 영역과 수준을 분석하였다. 분석 결과 융합과학과 통합과학 모두에서 가장 많이 나타난 과학의 본성 영역은 이론, 관찰추론, 사회문화로 나타났다. 두 교과서 모두에서 암시적인 관점의 서술의 비율이 명시적인 관점의 서술에 비해 높게 나타났다. 두 교과서의 과학의 본성을 서로 비교한 결과 각 출판사의 과학의 본성 서술 방향에 따라 과학의 본성의 빈도 및 명시성의 정도가 서로 다르게 나타났다. 교과서 집필방향에서 명시적인 서술이 더 증가하는 것이 필요하고, 일부 과학의 본성 영역에 편중되어 있는 현상을 줄이고 각 과학의 본성 영역이 균형 있게 배치되도록 하는 것이 필요할 것으로 보인다. Over the past decades, the importance of the nature of science has been emphasized. This study examined how the degree of reflection and the level of the nature of science (NOS) is advancing as the curriculum has been revised from ‘2009-revised-curriculum’ to ‘2015-revised-curriculum’. The area and level of the NOS in ‘Convergence-science’ of ‘2009-revised-curriculum’ and ‘Integrated-science’ of ‘2015-revised-curriculum’ were analyzed using the Nature of Science analyzing tool (NOSAT) which Lee Jeong-won et al. (2016) had made reflecting the definition of the NOS by Abd-El-Khalick et al. (2008). As a result of our analysis, the area of the NOS that appeared most in both ‘Convergence-science’ and ‘Integrated-science’ was ‘Theory’, ‘Inference’, and ‘Social and Cultural embeddedness’. In both textbooks of the curriculum, the proportion of implicit point of view was higher than that of explicit point of view. As a result of comparing the NOS in the textbooks, the frequency and the extent of the explicit descriptions of NOS differed according to the direction toward the nature of science of which each publisher writes. It is necessary to increase the number of explicit descriptions in the direction of textbook writing, and to reduce the phenomena that are biased toward the certain area of NOS and balance each area of NOS.

김치 관련 연구문헌의 분류분석 및 김치연구의 동향 (Ⅲ)

최홍식,김재이,민병태,전정태,공연희,홍정진,김나영 부산대학교 김치연구소 2002 김치의 과학과 기술 Vol.8 No.-

About 200 research papers and patents on kimchi(Korean fermented vegetable food) published In the years of 1997-2001 were collected and analyzed for the classification and review. This article covers the classified topics on the natures and kinds of raw materials, fermentation and related microorganisms, processing / preservation, kimchi packaging, biochemical changes, enzymes, quality, food chemistry, functional klmchi, general consideration on kimchi, and also some research nerds In the future.

연령에 따른 한국인 손 피부색 차이 분석

홍다검ㆍ이희경ㆍ이정현(Da Geom HongㆍHee kyung LeeㆍJeong Hyun Lee) 한국인체미용예술학회 2016 한국인체미용예술학회지 Vol.17 No.1

Recently, nail industry trends have been shifting from polish nail to gel nail. Because of the popularity of gel nail, the criteria for customers to choose colors have significantly changed. Therefore, there has been a rising demand for a nail color which goes well with skin color, not with the color of clothes, makes the hand more beautiful. Unlike a face, hand skin color isn’t corrected through makeup. Therefore, it is more difficult to find a color which is well matched with the skin tone. In this sense, the accurate analysis and classification of hand skin color which is the first step in the selection of nail color are required. However, it’s still very hard to find studies on hand skin color. To figure out the characteristics of Koreans’ hand skin color by age, this study analyzed differences in hand skin color by age after measuring the tone of the back of the hand and conducting quantitative analysis against 300 women living in Busan, Ulsan and Gyeongnam. The results revealed statistically significant difference (p.001). As the respondents were younger, a bright skin tone was observed. According to analysis on the distribution by the rank, ‘20s’ was the highest with 46% among those with a bright skin tone within top 100 ranks. In top 300 ranks, in contrast, ‘50s’ was the highest with 46% while ‘20s (8%)’ was the lowest. In terms of a skin tone, there was a considerable difference between ‘20s’ and ‘50s.’ Even though no big difference was found between ‘30s’ and ‘40s,’ a skin tone was brighter in the latter.