브레이징을 이용한 Ti/STS321L 접합체의 미세조직과 기계적 특성의 변화

구자명,정우주,한범석,권상철,정승부 대한용접접합학회 2002 대한용접·접합학회지 Vol.20 No.6

This study investigated variations of micro-structures and mechanical properties of Ti / STS321L joint with various bonding temperature and time using brazing method. According to increasing bonding temperature and time, it was observed that the thickness of their reaction layer increased due So increasing diffusion rate and time. From the EPMA results, Ti diffused to the STS321L substrate according to increasing bending time to 30min. Hardness of bonded interface increased with increasing bonding temperature and time due to increasing their oxides and intermetallic compounds. XRD data indicated that Ag, Ag-Ti intermetallic compounds, TiAg and $Ti_3Ag$ and titanium oxide, $TiO_2$ were formed in interface. In tensile test, it was found that the tensile strength had a maximum value at the bonding temperature of $900^{\circ}C$ and time of 5min, and tensile strength decreased over bonding time of 5min. The critical thickness of intermetallic compounds was observed to about $30\mu\textrm{m}$, because of brittleness from their excessive intermetallic compounds and titanium oxide, and weakness from void.

Fracture properties and crack tip constraint quantification of 321/690 dissimilar metal girth welded joints by using miniature SENB specimens

Bao, Chen,Sun, Yongduo,Wu, Yuanjun,Wang, Kaiqing,Wang, Li,He, Guangwei Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6

By using miniature SENB specimens, the fracture properties of the materials in the region of welded metal, 321 stainless steel heat affected zone, 690 alloy heat affected zone of 321/690 dissimilar metal girth welded joints were tested. Both the J-resistance curves and critical fracture toughness of the three different materials are affected by the crack size because of the effect of crack tip constraint. Groups of constraint corrected J-resistance curves of the three materials are obtained according to J-Q-M approach. The welded metals exhibit the best fracture resistance but the worst fracture resistance is observed in the material of 690 alloy heat affected zone.

보건의료 정보화 산업의 국민경제적 파급효과에 관한 연구

정우수,지경용,김소윤,김윤 대한의료정보학회 2007 Healthcare Informatics Research Vol.13 No.4

Objective: We firstly defined the Healthcare Information Technology Industry as the new industry and then analyzed it's National Economic Effects based on the Meta-phase Investment of Public Finance Plan. Methods: We took the In/Output Analysis of Inter-industry Relationships as the quantitative analysis method to analyze the affect on the Healthcare Information Technology Industry. Results: The EPI(Estimated Production Inducement) and the VAI(Value-Added inducement) were amounted to KRW 1.99 trillion and KRW 1.73 trillion each between 2006 and 2010. Moreover, the TEI(Total Employment Inducement) was estimated at about 2.9 thousand jobs during the same periods of time. Conclusion: We found the Economic Effects of the Healthcare Information Technology Industry contributed to the Core Growth Power of the overall a nation. In other words, it satisfied the desire of consumption on the healthcare and improved the quality of the life. (Journal of Korean Society of Medical Informatics 13-4, 321-333, 2007)

A321 NEO/ CEO 연료 효율성과 경제성 비교 연구

장성우,이영재,유광의 한국항공경영학회 2020 한국항공경영학회지 Vol.18 No.5

Aircraft types used by airlines on short and medium-haul routes include Boeing’s B737 series and Airbus’ A320 series. A321 is one of the A320 series, and recently the A321 NEO (New Engine Option) was delivered for the first time in Korea in 2019. The A321 NEO has similar external specifications compared to the existing A321 CEO (Current Engine Option). But, the A321 NEO is equipped with high-efficiency engines, which improves take-off performance and reduces fuel consumption compared with the CEO. The manufacturer claims that the A321 NEO has improved fuel efficiency by 15%. The purpose of this study was to verify the fuel efficiency improvement of NEO aircraft with actual operational results, not the propaganda and theory of the manufacturer. To this end, the fuel efficiency of NEO and CEO aircraft was checked in three ways. The first method was to compare the fuel efficiency index using two individual aircraft fuel efficiency models of NEO and CEO, and the second method was to compare the fuel efficiency index with one fuel efficiency model reflecting the CEO/NEO classification variable and the payload. As a result of the first model, depending on the amount of payload, NEO was superior to the CEO at 17% in fuel efficiency, and the second model result was excellent at a maximum of 15%. Third, a fuel efficiency model was created by adding ‘the outside air temperature on the route’ and ‘the amount of fuel economy change due to lengthy usage’ as independent variables to the second model. Although NEO aircraft performed better in fuel efficiency than CEO aircraft, the number dropped to a maximum of 10%. It is estimated that the fuel efficiency of the CEO aircraft was degraded due to the lengthy usage, while the fuel efficiency of the NEO aircraft was better due to newly manufacturing and operation. In conclusion, the fuel efficiency of the NEO aircraft was superior to that of the CEO aircraft, but the number was up to 10%, confirming that there is a separation from the manufacturer’s propaganda, theory, and existing research. In addition, this study showed the economic analysis of the NEO purchase project, which has the benefit of reducing fuel consumption and the cost of the difference in aircraft purchase price. As a result of analysis of payback years, present value, and sensitivity, the A321 NEO purchase project is economical if the fuel price is above a certain level. Through this study, it is used as a tool for verifying the reliability of the manufacturer’s data in terms of airline operation. In addition, it can be used as a basic tool for economic analysis & policy decision-making of similar projects such as introducing new aircraft models or installing new equipment. 항공사들이 중․단거리 노선에서 이용하는 항공기 기종으로 보잉사의 B737 시리즈와 에어버스사의A320 시리즈가 있다. A321은 A320 시리즈 중 하나이고, 최근에는 A321 NEO(New Engine Option)가출시되어 2019년 국내에 처음으로 도입되었다. A321 NEO는 기존 A321 CEO(Current Engine Option) 대비, 외부 제원은 유사하나, 고효율 엔진 장착으로 기존 CEO에 비하여 이륙성능이 향상되고 연료소모율이 감소한 것으로 알려져 있다. 제작사에서는 A321 NEO는 연료효율이 15% 향상되었다고 주장하고 있다. 실제 운영한 운항실적 자료로 NEO 항공기의 연료효율 향상 결과를 검증하고자 하였다. 이를위해 세 가지 방법으로 NEO와 CEO 항공기의 연료효율을 확인하였다. 첫 번째 방법으로 NEO와 CEO 의 개별 항공기 연료 효율성 모델 두 개를 이용하여 연료 효율성 지수를 비교하였고, 두 번째 방법으로 CEO/NEO 구분변수와 유상탑재량 변수를 반영한 연료 효율성 모델 한 개로 연료 효율성 지수를비교하였다. 첫 번째 모델 결과, 유상탑재량에 따라 다르지만, NEO가 CEO 대비 연료 효율성이 17% 수준으로 우수하였고, 두 번째 모델 결과는 최대 15%로 우수하였다. 세 번째로 두 번째 모델에 ‘항로상 외기온도’와 ‘오랜 사용에 따른 연비 변화량’을 독립변수로 추가하여 연료효율성 모델을 만들었다. NEO 항공기가 CEO 항공기 대비 연료효율이 우수한 실적을 나타냈으나, 그 수치는 최대 10% 수준으로 떨어졌다. 이는 CEO 항공기가 오랜 사용으로 연료효율이 저하된 반면, NEO 항공기는 최신 제작/운영으로 연료효율이 좋은 것에 기인한 것으로 추정된다. 결론적으로, NEO 항공기의 연료효율이 CEO 항공기 대비 우수함을 보였으나, 그 수치는 최대 10% 수준으로 제작사 선전과 이론, 기존 연구와 이격이 있음을 확인하였다. 추가로 실적의 연료 소모 감소를 Benefit로, 구매가격 차이를 Cost로 하는 A321 CEO 대비 NEO 도입 프로젝트의 경제성을 분석하였다. Payback Years, 현재가치 총량, 민감도 분석 결과로 A321 NEO 도입 프로젝트는 항공유 가격이 일정 수준 이상 시에 경제성 있음을 확인하였다. 본연구를 통해 항공사 운영 측면에서 제작사 자료의 신뢰성 확인 및 검증 도구로 삼고자 한다. 또한, 신기종 도입 혹은 신 장비 장착 등 유사한 프로젝트의 경제성 분석 및 정책적인 의사 결정에 기본 도구로 활용한다.

불안의 항변권

김성필 한양법학회 2018 漢陽法學 Vol.29 No.4

Wer aus einem gegenseitigen Vertrag vorzuleisten verpflichtet ist, kann gemäß § 321 Abs. 1 S. 1 BGB die ihm obliegende Leistung verweigern, wenn nach Abschluss des Vertrags erkennbar wird, dass sein Anspruch auf die Gegenleistung – etwa auf Zahlung des Kaufpreises oder des Werklohns – durch mangelnde Leistungsfähigkeit des anderen Teils gefährdet wird. Dies gilt nach einem aktuellen Urteil des Bundesgerichtshofs auch dann, wenn die Gefährdung der Leistungsfähigkeit des Vertragspartners nur vorübergehend ist. Auch ein vorübergehendes Leistungshindernis auf Seiten des Vorleistungsberechtigten kann ein Leistungsverweigerungsrecht des Vorleistungsverpflichteten gemäß § 321 Abs. 1 Satz 1 BGB begründen. Das Bestehen eines solchen Leistungsverweigerungsrechts schließt den Verzug des Vorleistungsverpflichteten aus. Zur Begründung eines solchen Leistungsverweigerungsrechts bedarf es seit Inkrafttreten des Schuldrechtsmodernisierungsgesetzes im Jahr 2002 keines Rückgriffs auf den Grundsatz von Treu und Glauben mehr. Voraussetzungen und Folgen eines auf die Gefährdung des Gegenleistungsanspruchs gestützten Leistungsverweigerungsrechts des Vorleistungsverpflichteten richten sich vielmehr nach § 321 BGB. Nach Abs. 1 Satz 1 der Vorschrift kann derjenige, der aus einem gegenseitigen Vertrag vorzuleisten verpflichtet ist, die ihm obliegende Leistung verweigern, wenn nach Abschluss des Vertrages erkennbar wird, dass sein Anspruch auf die Gegenleistung durch mangelnde Leistungsfähigkeit des anderen Teils gefährdet wird (sog. Unsicherheitseinrede). Die Gefährdung des Gegenleistungsanspruchs braucht, anders als in der früher geltenden Fassung, nicht auf einer Verschlechterung der Vermögensverhältnisse des Vorleistungsberechtigten zu beruhen; auch sonstige drohende Leistungshindernisse begründen die Einrede, wenn sie geeignet sind, die Erbringung der Gegenleistung zu verhindern oder vertragswidrig zu verzögern, oder wenn eine vertragswidrige Beschaffenheit der Gegenleistung von einigem Gewicht zu erwarten ist. Die Gefährdung der Gegenleistung muss im Gegensatz zu der bisherigen Regelung in § 321 BGB nicht nach Vertragsschluss entstanden sein; es genügt, dass sie erst zu diesem Zeitpunkt erkennbar geworden ist. Für § 321 BGB a.F. hat der Bundesgerichtshof demgegenüber angenommen, dass der bloße Bestand der Einrede einen Verzug des einredeberechtigten Vertragsteils ausschließt. Hieran hält der BGH auch nach der Neufassung der Vorschrift fest. Die Unsicherheitseinrede des § 321 BGB betrifft Leistungspflichten aus gegenseitigen Verträgen, also solche, die von vornherein in wechselseitiger Abhängigkeit von einander stehen. Dieses Gegenseitigkeitsverhältnis ist der Grund dafür, dass schon das Bestehen der Einrede des nichterfüllten Vertrages (§ 320 BGB) nach ständiger Rechtsprechung des Bundesgerichtshofs und nahezu einhelliger Ansicht im Schrifttum den Eintritt des Schuldnerverzugs hindert6. Entsprechendes gilt für das Einrederecht aus § 321 BGB. Die Verpflichtung zu einer Vorleistung betrifft lediglich die Modalitäten der Vertragsdurchführung und hebt die wechselseitige Abhängigkeit der Leistungspflichten aus dem gegenseitigen Vertrag nicht auf. Allerdings ist zu bedenken, dass der Vorleistungsberechtigte nicht immer zu erkennen vermag, ob die Vorleistung wegen einer Gefährdung des Gegenleistungsanspruchs zurückgehalten wird. Nur wenn er dies weiß, kann er aber von der ihm durch § 321 Abs. 1 Satz 2 BGB eingeräumten Möglichkeit Gebrauch machen, die Einrede durch Sicherheitsleistung oder durch das Bewirken seiner Leistung abzuwenden. Das zwingt indes nicht dazu, die aus dem Bestehen der Einrede folgenden Wirkungen abweichend von § 320 BGB zu behandeln. Die Interessen des Vorleistungsberechtigten werden dadurch gewahrt, dass es dem anderen Vertragsteil auf Nachfrage oder auf eine Aufforderung zur Leistung hin obliegt, den Grund der Leistungsverweigerung zu nennen. Erfährt der Vorleistu...

동적재료모델을 활용한 STS 321 스테인리스강의 고온성형성 평가와 초기 미세조직의 영향

조평석,이재관,황효운,이용재,이동근 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.12

General austenitic stainless steel has a problem with intergranular corrosion due to volatilizingchromium, which forms chromium carbide in a high temperature environment. By adding titanium as analloying element, STS 321 stainless steel has excellent creep resistance and intergranular corrosion resistanceat high temperatures, because the formation of chromium carbide is suppressed. It is important to find theoptimal process conditions for STS 321 stainless steel used in the aerospace field, because high temperatureprocessing is mainly applied, and defects or inhomogeneity of materials that occur during high temperatureprocessing lowers the yield of products. In this study, to investigate the effect of the initial microstructure onthe high-temperature deformation behavior of STS 321 stainless steel, a high-temperature compression testwas performed on two types of STS321 alloys with different initial microstructures. The temperature rangewas set at 50°C intervals from 800°C to 1100°C, and the strain rate was set at 10-1/sec intervals from 1 × 100/sec to 1 × 10-3/sec. Based on the experimental results, the thermal activation energy, which differed dependingon differences in the initial microstructure, was calculated. In addition, by deriving flow stress and processingmaps, the difference in energy dissipation efficiency depending on temperature and strain rate was explained,along with the initial microstructure and high-temperature deformation mechanism.

알루미늄 열용사 코팅된 AA5083-H321의 내식성 평가

한민수,박일초,김성준 한국부식방식학회 2023 Corrosion Science and Technology Vol.22 No.2

In this study, anti-corrosion effect was investigated through various electrochemical experiments afterapplying Al thermal spraying technology to AA5083-H321. Open circuit potential and anodic polarizationcurves were analyzed through electrochemical experiments in natural seawater. The shape of the surfacewas observed using a scanning electron microscope (SEM) and a 3D microscope before and after theexperiment. Component and crystal structure were analyzed through EDS and XRD. As a result, the surfaceroughness of AA5083-H321 and the Al thermal sprayed coating layer increased due to surface damagecaused by anodic dissolution reaction during the anodic polarization experiment. The corrosion rate ofAA5083-H321 was relatively low because the Al thermal spray coating layer contained structural defectssuch as pores and crevices. Nevertheless, the open circuit potential of the Al thermal spray coating layer innatural seawater was measured about 0.2 V lower than that of AA5083-H321. Thus, a sacrificial anodeprotection effect can be expected.

Spontaneous transposition of HzSINE1 into CYP321A2 is undetectable in the field populations of Helicoverpa zea

Li Shengyun,Chen Song,Dong Shuanglin,Zhang Min,Deng Zhongyuan,Ni Xinzhi,Huang Jinyong,Li Xianchun 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

The enrichment of transposable elements (TEs) within allelochemical- and insecticide-metabolizing P450 alleles in Helicoverpa zea enables these P450s to gain TE-introduced adaptive variations otherwise not readily available to cope with the ever-changing and diverse xenobiotic stress factors in varying cropping systems. The critical role of each TE-inserted P450 allele depends on whether the inserted P450 allele is more adaptive than its TE-free counterpart or not. Previous study has reported a HzSINE1-inserted CYP321A2 allele in a laboratory strain of H. zea reared with xenobiotic-free artificial diets. Here we show that the HzSINE1-inserted CYP321A2 allele transcribes into two HzSINE1 sequence-containing mutant mRNA isoforms of different length that encode an identical C terminus-truncated and heme-binding region deleted non-functional P450. Nonetheless, HzSINE1 insertion does not disrupt the regulatory functional aspect of CYP321A2 since this allele is constitutively expressed and highly inducible by the allelochemicals xanthotoxin, quercetin and chlorogenic acid. Furthermore, while the HzSINE1-inserted CYP321A2 allele is fixed in the laboratory strain, the insertion is purged in the bifenthrin-resistant strain and the Georgia field population of H. zea. To sum up, the HzSINE1-inserted CYP321A2 allele represents an allelochemical-inducible non-functional P450 allele that is selected against in the field populations frequently encountering toxic plant allelochemicals and synthetic insecticides. However, such an insertion can reach fixation under the xenobiotic-free laboratory rearing conditions most likely due to random genetic drift across multiple generations.

Cysteine-321 of Human Brain GABA Transaminase Is Involved in Intersubunit Cross-Linking

최수영,윤창식,김대원,장상호,이병룡,최희순,최수현,김소영,안재진,권오신,강태천,원무호,조성우,이길수,박진서,엄원식 한국분자세포생물학회 2004 Molecules and cells Vol.18 No.2

γ-Aminobutyrate transaminase (GABA-T), a key homodimeric enzyme of the GABA shunt, converts the major inhibitory neurotransmitter GABA to succinic semialdehyde. We previously overexpressed, purified and characterized human brain GABA-T. To identify the structural and functional roles of the cysteinyl residue at position 321, we constructed various GABAT mutants by site-directed mutagenesis. The purified wild type GABA-T enzyme was enzymatically active, whereas the mutant enzymes were inactive. Reaction of 1.5 sulfhydryl groups per wild type dimer with 5,5′- dithiobis-2-nitrobenzoic acid (DTNB) produced about 95% loss of activity. No reactive -SH groups were detected in the mutant enzymes. Wild type GABA-T, but not the mutants, existed as an oligomeric species of Mr = 100,000 that was dissociable by 2-mercaptoethanol. These results suggest that the Cys321 residue is essential for the catalytic function of GABA-T, and that it is involved in the formation of a disulfide link between two monomers of human brain GABA-T.

AISI 321 스테인리스강의 크리프-피로 상호작용에 미치는 TiC 및 Cr_23C_6 입계탄화물의 영향

閔敬善,南壽祐,李守燦 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.10

In order to investigate the effects of TiC and Cr_23C_6 carbides on the creep-fatigue behaviors, total strain range controlled creep-fatigue tests were conducted at 600℃ in the TiC and Cr_23C_6 aged AISI 321 stainless steels with various carbide densities at grain boundary. It is observed that creep-fatigue lives of small TiC and TiC aged alloys are longer than that of Cr_23C_6 aged alloy in the same test conditions. To verify differences of creep-fatigue life between TiC and Cr_23C_6 aged alloys, microstructural observations are conducted by scanning electron microscope(SEM) and transmission electron microscope(TEM). It is expected that cavitation resistance of TiC aged alloy is stronger than that of Cr_23C_6 aged alloy. From the microstructural observations, it is verified that formation and growth of grain boundary cavities in TiC carbides are more retarded than in Cr_23C_6 carbides. Therefore, it is suggested that the types of carbides are a more prominent factor than the density of carbides for grain boundary cavitation in austenitic stainless steels.