선택적 레이저 용융법으로 제조된 Ti-6Al-4V 합금의 고 주기 피로 특성에 미치는 건식 전해 연마의 영향

양동훈,김영균,황유진,김명세,이기안,Yang, Dong-Hoon,Kim, Young-Kyun,Hwang, Yujin,Kim, Myoung-Se,Lee, Kee-Ahn 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.6

Additively manufactured metallic components contain high surface roughness values, which lead to unsatisfactory high cycle fatigue resistance. In this study, high cycle fatigue properties of selective laser melted Ti-6Al-4V alloy are investigated and the effect of dry-electropolishing, which does not cause weight loss, on the fatigue resistance is also examined. To reduce the internal defect in the as-built Ti-6Al-4V, first, hot isostatic pressing (HIP) is conducted. Then, to improve the mechanical properties, solution treatment and aging are also implemented. Selective laser melting (SLM)-built Ti64 shows a primary α and secondary α+β lamellar structure. The sizes of secondary α and β are approximately 2 ㎛ and 100 nm, respectively. On the other hand, surface roughness Ra values of before and after dry-electropolishing are 6.21 ㎛ and 3.15 ㎛, respectively. This means that dry-electropolishing is effective in decreasing the surface roughness of selective laser melted Ti-6Al-4V alloy. The comparison of high cycle fatigue properties between before and after dry-electropolished samples shows that reduced surface roughness improves the fatigue limit from 150 MPa to 170 MPa. Correlations between surface roughness and high cycle fatigue properties are also discussed based on these findings.

견관절의 임상적 평가도구에 관한 고찰

양동훈,김건형,김행범,최양식,박영배,Yang, Dong-Hoon,Kim, Kun-Hyung,Kim, Haeng-Beom,Choi, Yang-Sik,Park, Young-Bae 대한침구의학회 2007 대한침구의학회지 Vol.24 No.6

Objectives : A number of instruments have been developed to measure the quality of life in patients with various shoulder disorders. Much progress has been made in this area, and currently an appropriate instrument exists for each shoulder state. The purpose of this study is to review the instruments that are currently in use for assessing the shoulder joint. Methods : A literature research was performed to choose appropriate scales for assessment of function and the disability of the shoulder. Theoretically based scales were selected for review. Therefore, 11 scales were reviewed. The status of scales involved in shoulder treatment of acupuncture throughout several countries was evaluated. Results : 11 scales: The American shoulder and elbow surgeons evaluation form(ASES), Constant Shoulder Score, The disabilities of the arm, shoulder and hand(DASH), Shoulder Disability Questionnaire (SDQ), The Shoulder Pain And Disability index(SPADI), The simple shoulder test(SST), Oxford Shoulder Questionnaire(OSQ), The Rotator Cuff quality-of-life Measure(RC-QoL), Western Ontario Shoulder Instability Index(WOSI), Western Ontario Osteoarthritis of the Shoulder Index(WOOS), Western Ontario Rotator Cuff Index(WORC), wereevaluated. Each measurement has its own composition and characteristics. Their validity, reliability, responsiveness and practical characteristics were already evaluated. We found 3 domestic and 10 overseas papers about shoulder treatments using acupuncture assessed with shoulder scales. Conclusions : In clinical research, the selection of the measurement scale should take account of the condition of disease, the patient's traits and the characteristics of the research. Moreover, appropriate scales, which havevalidity, reliability, responsiveness and practical characteristics, are needed to enhance the quality of research.

선택적 레이저 용융 공정으로 제조된 AISI 316L 합금의 인장 및 충격 인성 특성에 미치는 응력 완화 열처리의 영향

양동훈,함기수,박순홍,이기안,Yang, Dong-Hoon,Ham, Gi-Su,Park, Sun-Hong,Lee, Kee-Ahn 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.4

In this study, an AISI 316 L alloy was manufactured using a selective laser melting (SLM) process. The tensile and impact toughness properties of the SLM AISI 316 L alloy were examined. In addition, stress relieving heat treatment (650℃ / 2 h) was performed on the as-built SLM alloy to investigate the effects of heat treatment on the mechanical properties. In the as-built SLM AISI 316 L alloy, cellular dendrite and molten pool structures were observed. Although the molten pool did not disappear following heat treatment, EBSD KAM analytical results confirmed that the fractions of the low- and high-angle boundaries decreased and increased, respectively. As the heat treatment was performed, the yield strength decreased, but the tensile strength and elongation increased only slightly. Impact toughness results revealed that the impact energy increased by 33.5% when heat treatment was applied. The deformation behavior of the SLM AISI 316 L alloy was also examined in relation to the microstructure through analyses of the tensile and impact fracture surfaces.

동결견(凍結肩) 환자의 동서협진 치료의 임상효과 비교연구 - 견관절 가동운동범위(ROM) 변화를 중심으로 -

남동우,김행범,양동훈,임사비나,김건식,이두익,이재동,최도영,이윤호,Nam, Dong-Woo,Kim, Haeng-Beom,Yang, Dong-Hoon,Lim, Sa-Bi-Na,Kim, Keon-Sik,Lee, Doo-Ik,Lee, Jae-Dong,Choi, Do-Young,Lee, Yun-Ho 대한침구의학회 2006 대한침구의학회지 Vol.23 No.5

Objectives : To establish an effective collaborate medicine treatment of acupuncture and western medicine for treating frozen shoulder patients. Methods : 59 voluntary patients were randomly assigned to Eastern treatment group(E group, n=22), Western treatment group(W group, n=17) and East-West treatment group(EW group, n=20). The E group received acupuncture treatment on LI15, TE14, GB21 and Master Dong's acupuncture points, Shin-gwan and Gyun-joong, twice a week for 4 weeks. The W group received suprascapular nerve block, subacromial injection and trigger point injection, twice a week for 4 weeks. The EW group received acupuncture and injection treatment including nerve block All groups were instructed to practice self exercise during their daily lives. Evaluations were made before treatment and after treatment based on the change in shoulder Range of Motion(ROM) and the patient's satisfaction concerning the treatment was measured by Visual Analogue Scale(VAS). The obtained data were analyzed and compared. Results : The patient's satisfaction scores were E group 5.67, W group 7.73 and EW group 7.67. The E group and the EW group showed significant improvement in abbduction, adduction and flexion(p<0.05). The W group showed significant improvement in adduction(p<0.05). Abduction significantly improved(p<0.05) in the EW group compared to E group and W group. Flexion also showed improvement in the EW group, but the difference among the 3 groups was statistically insignificant. The three group's difference of change in extension and adduction was insignificant(p>0.05). Conclusion : Acupuncture and nerve block alone significantly improved ROM in frozen shoulder patients. Also collaborate treatment of acupuncture and nerve block significantly improved ROM in frozen shoulder patients. But the difference of the three treatments were significant only for improving abduction(p<0.05).

연구논문 : 한국상장 중국기업의 이익조정과 가치평가

양동훈 ( Dong Hoon Yang ),김령 ( Ling Jin ),홍영도 ( Young Do Hong ) 한국회계학회 2015 회계저널 Vol.24 No.5

2005년 외국기업의 국내 상장이 허용된 이래 16개 중국기업들이 국내 증권시장에 상장하였다. 그러나 그중 3개 기업이 회계부실문제로 상장이 폐지되고 또 다른 3개 기업은 국내시장에서 기업가치가 저하되자 자진하여 상장을 폐지하는 등 국내에서 상장된 중국기업이 한국 시장에서 신뢰를 얻지 못하고 있다. 본 연구는 국내에 상장된 중국기업이 시장에서 신뢰를 얻지 못하는 이유를 중국기업의 상장전후의 이익조정으로 보고 중국기업이 같은 기간에 상장한 한국기업보다도 상장전후에 이익조정이 더 큰지를 검증하였다. 실증분석 결과 한국상장 중국기업은 같은 기간에 상장한 한국기업보다 상장직전년도와 상장년도에 이익조정을 더 많이 하는 것으로 분석되었다. 또한 이러한 이익조정결과 중국기업들의 ROA가 상장 이후에 한국기업에 비하여 하락폭이 더 큰 것으로 나타났다. 그리고 2011년 3월 중국고섬기업이 회계부실문제로 거래가 정지된 사건은 중국기업이 보고한 재무제표에 대하여 시장이 불신하게 된 계기가 되었다. Ohlson모형으로 분석한 결과 고섬사태이후에는 중국기업이 보고한 회계이익의 기업가치반영정도가 고섬사태이전에 비하여 유의하게 약화되었음을 확인하였다. 추가로 한국상장 중국기업의 Tobin Q비율을 고섬사태전후로 나누어 비교한 결과 고섬사태이후에 중국기업의 기업가치가 한국상장기업에 비하여 유의하게 낮음을 확인하였다..중국기업이 중국에 상장하지 않고 한국시장을 선택하게 되는 이유로 한국시장의 상장요건이 중국에 비하여 엄격하지 않고 또한 상장에 소요되는 기간이 짧아 중국시장에 상장하는 경우보다 용이하게 자금을 조달할 수 있음에 기인한다. 따라서 한국시장을 선택한 중국기업들은 재무상태나 회계이익의 질이 취약할 수 있다. 회계가 부실한 기업들이 국내시장에 상장을 할 경우 국내투자자들의 투자손실을 초래할 뿐 아니라 시장의 불신으로 인하여 우수한 해외기업이 국내시장에 상장하는데 장애요인이 되고 있다. 본 연구는 외국기업의 한국시장 상장전의 회계감사절차를 강화해야 할 필요가 있으며 상장심사기준에서도 회계부실여부를 보다 면밀히 검증할 필요가 있음을 시사한다. Sixteen Chinese firms have initiated public offerings in Korean stock market since foreign firms were allowed IPO in Korean securities market. As of 2015, three firms of them have been delisted due to their accounting scandals and other three firms volunteerly delisted because their stock prices were devaluated in Korean market compared to other markets caused by alleged investors’ distrust about financial statements of Chinese firms. Under the assumption that the distrust of Chinese firms resulted from Chinese firms’ earning management around IPO, we investigated whether Chinese IPO firms’ earning management had been higher than that of Korean IPO firms in one year prior to IPO and in the year of IPO by using discretionary accruals as the earnings management proxy measured by the both modified Jones model and Kothari``s performance matched model. Our empirical results indicates that Chinese firms listed in Korean market had exhibited significantly higher discretionary accruals than those of Korean firms around IPOs, which means Chinese firms had managed the reported earnings of one year prior to IPO and in the year of IPO using discretionary accruals to increase IPO prices. Further, the earnings management had led to the decline in ROA in the next year of IPO, thereby resulting in significant investment loss of Korean investors. Our study also showed that the degree of decrease in ROA of Chinese IPO firms had been greater than that of Korean firms. We next found that the relationship between stock prices and reported earnings of Chinese IPO firms became weaker after the Chinese “Gosum accounting scandal” which was a crucial event that triggered Korean investors’ distrust of financial statements of Chinese firms. We have also found that Tobin’s Q ratios of Chinese firms were significantly lower than those of Korean firms after the scandal, suggesting that Chinese firms suffered from devaluation of their stock prices after the scandal. The devaluation of Chinese firms in Korean market had led voluntary delistings of additional Chinese firms, their movements to stock markets of other countries and, to make things worse, the stop of new IPO of Chinese firm in Korean market. As a result, many Korean investors who invested in the stocks of Chinese IPO firms had made losses and lost the opportunity to invest new Chinese IPO firms in Korean market. We conjecture there are three plausible reasons for Chinese firms to choose Korean market for IPO rather than Chinese market. First, Chinese IPO firms applying for Korean market may not be so financially sound as those applying for Chinese market because the listing criteria to Korean market is relatively easier than the criteria of Chinese market. Also, Chinese firms that were urgent in financing IPO money would choose Korean market of which IPO process is generally faster than that of Chinese stock market. Second, the complicated corporate governance may have caused the earnings management. If Chinese firms intend to list in foreign stock markets, they need approvals from Chinese financial authority. Due to difficulty with getting the approval, they set up the holding companies in other countries to get around the difficulty and list these holding companies in foreign stock markets including Korean market. This practice may result in the irresponsibility of the compliance. Finally, the probable low accounting quality of Chinese firms could be attributable to the difference between K-IFRS and C-IFRS. Chinese firms have to prepare financial statements of both standards, but they may not fully understand K-IFRS and Korean auditors have difficulty with auditing Chinese firms that are located geographically far away and culturally unfamiliar. Collectively, empirical results of our study imply that audit process for foreign pre-IPO firms should be more thorough and the policy makers should tighten screening criteria in examining accounting reports of foreign IPO firms.

瘀血辨證說問紙 開發

양동훈 ( Dong-hoon Yang ),박영재 ( Yong-jae Park ),박영배 ( Young-bae Park ),이상철 ( Sang-chul Lee ) 대한한의진단학회 2006 大韓韓醫診斷學會誌 Vol.10 No.1

Background and Objectives: The diagnosis of Blood stasis pattern is one of the most important methods in oriental medicine. The aim of this study is to Develop clinically useful questionnaire of Blood stasis(瘀血) and quantitative analysis. Methods: The questionnaire including symptoms and signs for diagnosis of Blood stasis pattern is studied by delphi method and statistical analysis. Result: By the delphi method and statistical analysis, 14 Items of questionnaries are choosen. Conclusion: Further research is necessary for improvement reliabilities and validities of the questionnaires of Blood stasis pattern.

한중일 3국 협력 현황과 발전 과제 연구

양동훈(Yang, Dong-Hoon) 동북아시아문화학회 2020 동북아 문화연구 Vol.1 No.62

Sharing geographic proximity and importance for one another, South Korea, China, and Japan experienced cooperation at times and frictions at other times, and yet have established a relatively peaceful relationship for thousands of years. However, Japan"s policy of aggression, which began in the 19th century and escalated in the 20th century, along with the ideological changes in China and the Korean peninsula caused ruptures in the peaceful relationship. In the 21st century, the relationship worsened to the level of hostility due to unresolved historical and territorial issues and the nuclear crisis caused by North Korea. In terms of economic aspects, the three countries have made some progress in cooperating with one another. However, there are still many obstacles to their peaceful cooperation and development in terms of international situation, political system, and historical perceptions. A country can have more diverse dreams and enjoy more things when its power is stronger. However, it is impossible for a country to choose its neighboring countries or unilaterally decide the nature of its relations with neighboring countries. Moreover, the Northeast Asia region, represented by South Korea, China, and Japan, has been fraught with changing international circumstances in the 20th century due to the confrontational Russia-United States relations, the Korean War and the North Korean nuclear issue, which have considerably affected mutual exchanges and development in the three countries. Therefore, when it comes to trilateral cooperation between South Korea, China and Japan, it is not beneficial for respective countries to seek cooperation without resolving existing disputes and contradictions. The development of this trilateral cooperation can change regional order while ensuring certain level of power for the countries, which can influence various positive changes in Northeast Asia and East Asia. Therefore, cooperation between South Korea, China and Japan must be carried out as an international trend. Implementation of a full-scale cooperation would be desirable by granting adequate initiative and making institutional improvement for cooperation in addition to providing various motivations. Thus, through trilateral cooperation, the three countries should serve as a great driving force in leading peace and development at a global level beyond East Asia.

민주주의 질(質)의 개념화와 평가

양동훈(Yang Dong-Hoon) 경성대학교 사회과학연구소 2011 社會科學硏究 Vol.27 No.1

민주주의 질의 문제는 민주주의의 개념적 확장의 문제일 수도 있다. 그러나 또한 신민주체제에 대한 다차원적인 이해와 평가의 문제일 수도 있다. 민주주의 질의 이해와 평가는 개념적으로 신민주체제의 다차원적 접근을 통해서도 가능하다. 오도넬(O'Donnell)과 관련 학자들의 확장적 개념화는 민주주의의 개념적 모호성을 다소 증대시키고 결과적으로 민주주의 질에 대한 유의미한 논의의 기반을 다소 불안정하게 만든다. 달(Dahl)의 다두제와 그 조건에 대한 논의에 근거하여 민주주의 질의 문제를 대안적으로 다차원의 관점에서 논의할 수 있다. 민주주의 질을 다두제의 속성과 그 다양한 조건과 환경의 상호 작동의 관계로 이해하고 신민주체제의 민주주의 질에 대하여 정치체제 영역의 내재적 차원, 국가영역의 외재적 차원, 사회영역의 환경적 차원으로 접근한다. 민주주의의 궁극적인 특성인 시민통제와 시민평등의 관점과 기준에서 각 차원의 주요 속성들을 논의하는 것이 민주주의 질의 총체적인 이해와 평가에 유리하다. 또한 민주주의 질의 다차원적인 평가에서 질적 평가의 경험적인 타당성을 제고하기 위하여 그 대상, 기준, 주체에 대하여 분석적으로 구분하고 논의하는 것이 필요하다. The quality of democracy may be a question of conceptual expansion. O'Donnell and some other political scientists have tried to expand the concept of democracy in the discussion of the quality of democracy. Their efforts have led to some conceptual confusion and instability to some extent. On the other hand, the quality of democracy could be a question of multidimensional understanding, assessment and improvement. We can conceptually approach it from a multidimensional perspective of neodemocracy. Dahl‘s concept of polyarchy suggests that we can study the quality of democracy systematically from a multidimensional view. We can see the quality of democracy as a mutual interaction between the internal attributes of polyarchy and its surrounding conditions. We can study the quality of democracy from the internal, external, and environmental, dimension of neodemocracy. The internal dimension includes some attributes of the political regime. The external dimension consists of some state-related attributes. The environmental dimension is closely related to some attributes of the national and international society. Exclusion or inclusion of such attributes in each dimension can be based on the core principles of democracy, popular control and equality. The quality of democracy depends on the total assessment of all such attributes. The quality assessment requires the analytical distinction of its object, assessing criteria, and assessor, which can lead to improve the validity of assessment.

공시의 질이 부채조달비용에 미치는 영향

양동훈(Dong Hoon Yang),이상철(Sang Cheol Lee),윤종철(Jong Chul Yoon) 한국경영학회 2011 經營學硏究 Vol.40 No.3

This paper examines the effect of firms` disclosure quality on cost of debt financing. We conjecture that poor quality of disclosure decrease information asymmetry between managers and market participants, thereby reducing cost of debt capital. Francis et al.(2005) argue that accruals quality (i.e., disclosure quality) tells investors about mapping of accounting earnings into cash flow. Relatively poor disclosure quality weakens this mapping, and therefore, increases information risk. Accordingly, firms with more information risk will have higher costs of capital. Disclosure quality is difficult to measure because it is not directly observable. Disclosure measures used in prior research include analysts` evaluations of firms` disclosure practices by the Association for Investment Management and Research (AIMR) (e.g., Lang and Lundholm 1996; Botosan Plumlee 2002), a disclosure index created by the researcher (e.g., Singhvi and Desai 1971; Botosan 1997), and an indirect measure of disclosure quality combining three correlated variables of institutional holdings, low bid-ask spread, and high analysts following that are associated high disclosure quality (Lee et al. 2006). Among these approaches, we use the Lee et al.(2006)`s measure to estimate a proxy for disclosure quality. In doing so, we perform a factor analysis on foreign investors` holdings, analysts following, audit quality, number of shareholders, and listing status to create one variable (i.e., common factor) for disclosure quality. The major benefit of using a common factor, as maintained by Lee et al. (2006), is that it will be less subject to random measurement errors. Our measure of firms` cost of debt is their senior debt ratings assigned by Korea Investors Service (KIS), one of the Korean major bond-rating firms. KIS assigns bond ratings of Korean firms on a scale of twenty grades from AAA to D. Following Ahmed et al.(2002), we code these ratings such that AAA corresponds with 20 (the best rating) and D (the worst rating) with 1 to facilitate our empirical analyses. We also use the ratio of interest to interest-bearing debt for a robustness check of main results. Prior studies has found that firm`s debt ratings are closely associated with its eventual payoff of interest and principal obligations. We draw an initial sample of firms listed on the Korea Stock Exchange for five years from 2003 to 2007. We obtain data on bonds by searching through FnGuide and KIS-Value databases. Among these, non-financial firms that satisfy all of the following criteria are selected: (1) fiscal-year ending December 31, (2) listed since 5-year before each sample year, and (3) availability of relevant financial data including daily and monthly stock returns. This sample selection procedure yields an final sample of 589 firm-year observations. To test our hypothesis of the effect of firms` disclosure quality on cost of debt financing, we carry out OLS regressions and an ordered-logit regression analyses. We find that firms with poorer disclosure quality have lower debt ratings and higher ratios of interest expense to interest-bearing debt. This results are consistent with several alternative specifications of the disclosure quality and cost of debt metrics. Our empirical findings confirm the notion that greater disclosure reduces information risk arising from investors` estimates of the parameters of an asset (i.e., bonds)`s return or payoff distribution, where information risk is captured by disclosure quality. Our paper makes two contributions. First, consistent with theories that demonstrate a role of information risk in asset pricing, we show that firms with poor disclosure quality have higher costs of debt capital than do firms with good quality. Second, we provide support for using a parsimonious variable measured by factor analysis on a set of variables that are correlated each other but are significantly associated with disclosure quality.

호박 1 代雜種의 純度檢定을 위한 phosphoglucomutase의 同位酵素 分析에 관한 硏究

Dong Hoon Yang(梁東勳),Hyo Guen Park(朴孝根),Su Geun Chae(蔡洙根) 한국육종학회 1986 한국육종학회지 Vol.18 No.4

Extracts from cotyledons of imbibied squash seeds of three commercial F₁ hybrids and their six parental inbred lines were analized by starch gel electrophoresis and stained for phosphoglucomutase(PGM;E.C-2.7.5.1) in order to investigate the possibility of use of the isozyme variants in determining purity of F₁ seeds. Diagnostic band variants for phosphoglucomutase were found in the most cathodal zone from the two parental inbreds of a F₁ hybrid. The band pattern and activity of PGM was stable during three days of germination. The band pattern of PGM was expressed by three loci. PGM-3 varients was controlled by two co-dominant alleles, PGM-3F and PGM-3S, at one locus.