Evaluation of Hot Deformation and Dynamic Recrystallization Behaviors of Advanced Reduced-Activated Alloy (ARAA)

Sang‑Wook Kim,Hyeon‑Woo Son,Taek‑Kyun Jung,Young‑Bum Chun,Yi‑Hyun Park,Ji‑Woon Lee,Soong‑Keun Hyun 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4

The hot deformation behavior of advanced reduced-activation alloy (ARAA) was investigated using hot torsion tests. Thefl ow stress decreased as deformation temperature increased and as strain rate decreased. The fl ow behavior demonstratedthe typical dynamic recrystallization (DRX). Based on the constitutive analysis of peak stress, the activation energy for hotdeformation was found to be 330.3 kJ mol −1 . Peak stress was analyzed as a function of the Zener–Hollomon parameter, andcalculated and experimental values were in good agreement. A DRX kinetic model for ARAA was derived with deformationconditions based on the Avrami-type model. It was confi rmed that the volume fraction of dynamically recrystallized grainsincreased as deformation temperature increased and as strain rate decreased. The necklace structure and grain boundarybulging were observed in the deformed microstructure of ARAA. The suggested DRX mechanism for ARAA during hotworking is discontinuous DRX.

판상형 충전제의 함량과 배향에 따른 PP복합체의 영률 변화 연구

서상범(Sang Bum Seo),이용현(Yong Hyun Lee),정선경(Sun Kyoung Jeong),이승구(Seung Goo Lee),이기윤(Kee Yoon Lee) 한국고분자학회 2012 폴리머 Vol.36 No.2

이 논문은 판상형 충전제의 함량과 배향에 따라 폴리프로필렌 복합체의 영률 변화에 미치는 영향을 연구 하였다. 이론적인 예측은 Lee와 그의 연구자들에 의해 제안된 두 개의 종횡비, ρα=a1/a3과 ρβ=a1/a2 를 이용하여 3차원 타원체의 형상을 계산하였고 실험값과 비교 분석하였다. 판상형 충전제로 운모와 탈크를 사용하였다. 충전제의 형태는 SEM을 이용해 관찰하였고, 종횡비는 고분자의 흐름을 기준으로 좌표축을 설정하여 통계적 방법으로 계 산하였다. 충전제가 운모인 경우에 ρα=13.5와 ρβ=1.8이었고, 탈크의 경우는 ρα=3.8과 ρβ=1.4이었다. 또한 충전제 의 2개의 종횡비와 함량이 기계적 물성에 미치는 영향을 실험적으로 연구하였다. 운모의 경우 30 wt% 함량일 때 E11이 약 2.7배 향상되었다. 탈크의 경우는 E11이 약 2.3배 향상하였다. This paper studied the effects of the content and the orientation of the disk shape fillers on the modulus of PP composites. The experimental results were compared with the theoretical calculations which included the three dimensional ellipsoids and analyzed by two aspect ratios, ρα=a1/a3 and ρβ=a1/a2 proposed by Lee and his researchers. Mica and talc were used as disk shape fillers in the composites. The shapes of mica and talc were observed by SEM and aspect ratios were statistically calculated. For the case of mica, the average aspect ratios were ρα=13.5 and ρβ=1.8, and for the case of talc, they were ρα=3.8 and ρβ=1.4. Also, the effects of two aspect ratios and the content of filler on the mechanical properties were studied: For 30 wt% of mica, E11 increased up to about 2.7 times, and for the other case of talc, E11 increased up to about 2.3 times, respectively.

해외사례 벤치마킹에 기반한 국내 CM 대가체계 개선 시사점 도출

김상범,이정대,김재욱,Kim, Sang-Bum,Lee, Jeong-Dae,Kim, Jae-Wook 한국건설관리학회 2008 건설관리 : 한국건설관리학회 학회지 Vol.9 No.1

국내 CM은 2001년 건설산업기본법에 의해 개념과 범위가 정의된 후 지속적인 성장을 계속해 오고 있다. 하지만, 이러한 CM 제도에 기반한 성장에도 불구하고 국내에서의 CM 적용성과는 기대치에 비해 상대적으로 낮은 것으로 나타났다. 그 주요원인의 하나로 국내 CM제도가 책임감리에 비하여 업무범위가 넓지만, 대가기준은 책임감리에 비해 낮기 때문인 것으로 분석되었다. 따라서, 국내 CM 대가체계의 합리적인 기준을 정립하는 것이 시급할 것으로 판단된다. 본 연구에서는 CM 대가체계의 합리적인 기준을 마련하기 위하여 CMAA, ASCE, DOE, DOL 등의 다양한 해외사례 벤치마킹 연구를 통하여 국내 CM 대가체계를 비교하여 대가 상승요인을 추정하고 대가산정 개선방향을 제시하였다. 분석결과 대가수준은 해외에 비하여 현저하게 낮은 수준인 것으로 판단되었으며, 업무범위는 해외와 비교하여 그 폭이 좁으며 획일적인 구조를 가진 것으로 분석되었다. 따라서, 본 연구에서는 글로벌스탠다드에 따르는 국내 CM 대가체계를 개선하기 위하여 실비정액보수가산(Cost Plus Fixed Fee) 방식을 제시하고, 입 낙찰 전반에 걸친 CM 대가체계에 대한 기준(Framework)을 제시하였다. The Korean Construction Industry significantly contributed to the Korean economic development not only by preparing the domestic infrastructure but also by successfully conducting various international projects. However, major incidents such as the collapse of Sung-Su Bridge and Sam-Pung Department Store along with stagnation of Korean Economy have raised questions about underlying systematic problems of the Korean Construction Industry. As a solution to resurrect the Korean Construction Industry, the Construction Management (CM) system introduced in late 1990's and increasingly utilized as an innovative delivery system. Despite of the fast growth of CM, the performance of CM has not been up to the hype and low CM fee has been identified as one of the main reasons of unsatisfactory CM performance. Therefore, this research attempted to propose ways of improving 'CM Fee Guidelines' published by Korean Ministry of Construction and Transportation by conducting a benchmarking study on Global Standards of estimating CM Fee. International organizations benchmarked in this research include CMAA, ASCE, DOL, DOE, etc. Various investigation and analysis revealed that Korean 'CM Fee Guidelines' need to significantly modified comparing to Global Standards. This research also tried to prepare recommendations to improve the CM deliver system focusing on the 'Method of CM Fee Estimation' and Selection of a CM firm as an owner's agent.

병원구매업무에 있어서의 전자상거래 도입에 관한 연구 : 구매부서 관리자의 인식도를 중심으로 Focused on the Understanding of Purchasing Managers

황은범 ( Eun Bum Hwang ),남상요 ( Sang Yo Nam ),하호욱 ( Ho Uk Ha ),이창은 ( Chang Eun Lee ) 한국병원경영학회 2001 병원경영학회지 Vol.6 No.3

This study is focused that the electronic commerce(EC) on the purchasing section may improve the efficiency and transparency of the hospitals management. After reviewing the purchasing activity of hospitals, I study the introduction, expected effects, and problems of EC. So, I am going to provide basic information for activating EC. The samples are managers of 170 hospitals, which are located on Seoul. As a result of collection this survey, I analyze 79 hospitals. For data analysis, I use X^2-test and ANOVA for purchasing management and the relevance of EC according to the level of care. The results of this study are 1. the problems on the management of purchasing section are : firstly, they don't have sufficient time to study market. Secondly, it is difficult to find competitive suppliers. And, lastly, they cannot gather a lot of information about the price of products. 2. There are many answers of the needs on the introduction of B2B. However, some hospitals think they don't need it. But, the most answers are that the EC will be settled within 4 years. So, we can realize that these hospitals are getting interested on the EC. On the other hand, I find that they prefer outside EC companies for the introduction of EC. 3. On the expected effects on EC, first is the effectiveness of the market survey. The next is to collect information of adequate price of products owing to clear transaction, find easier new suppliers and gather useful data. 4. On the external problems of the introduction of EC, there is low credibility related to the security and the weakness of suppliers' information system. Especially, on the Real Transaction Price Payment system, the bigger bed size, the higher understanding on these problems. On the internal problems of the introduction of EC, first is the burden of the introduction of EC and operating cost. Especially, on the burden of the disclosure of revenue source, the smaller bed size, the higher understanding on this problem. So, this is a point which deserves my attention statistically. However, this shows relatively little understanding about incomplete the standard of product category and the weak information system of hospital. Through this study, I am going to suggest 3 points for the activation of the introduction of EC on hospitals. 1. The reform of the Real Transaction Price Payment System on medical supplies and materials for medical treatment. 2. The establishment of the standard of product category. 3. The promotion of information system based on network.

e-Poster : Immunohistochemical study of Foxp3 expression in Hansen disease (초)

( Sang Woo Lee ),( Ji Yeon Byun ),( Ki Bum Myung ),( You Won Choi ),( Hae Young Choi ),( Jong Pill Kim ) 대한피부과학회 2010 초록집 Vol.48 No.20

Validation of HPLC Method for Simultaneous Analysis of Major components in `Galgeunhaegi-tang` Mix Soft Extract

Sung-Ok Moon,Ha-Yeong Lee,Min-Ju kim,Jong-Bum Kim,Ji-Bum Lee,Hwa-Dong Lee 한국분석과학회 2018 학술대회논문집 Vol.2018 No.11

X-ray Raman scattering study of MgSiO3 glass at high pressure: implication for triclustered MgSiO3 melt in Earth's mantle.

Lee, Sung Keun,Lin, Jung-Fu,Cai, Yong Q,Hiraoka, Nozomu,Eng, Peter J,Okuchi, Takuo,Mao, Ho-Kwang,Meng, Yue,Hu, Michael Y,Chow, Paul,Shu, Jinfu,Li, Baosheng,Fukui, Hiroshi,Lee, Bum Han,Kim, Hyun Na,Yoo National Academy of Sciences 2008 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.105 No.23

<P>Silicate melts at the top of the transition zone and the core-mantle boundary have significant influences on the dynamics and properties of Earth's interior. MgSiO3-rich silicate melts were among the primary components of the magma ocean and thus played essential roles in the chemical differentiation of the early Earth. Diverse macroscopic properties of silicate melts in Earth's interior, such as density, viscosity, and crystal-melt partitioning, depend on their electronic and short-range local structures at high pressures and temperatures. Despite essential roles of silicate melts in many geophysical and geodynamic problems, little is known about their nature under the conditions of Earth's interior, including the densification mechanisms and the atomistic origins of the macroscopic properties at high pressures. Here, we have probed local electronic structures of MgSiO3 glass (as a precursor to Mg-silicate melts), using high-pressure x-ray Raman spectroscopy up to 39 GPa, in which high-pressure oxygen K-edge features suggest the formation of tricluster oxygens (oxygen coordinated with three Si frameworks; 3O) between 12 and 20 GPa. Our results indicate that the densification in MgSiO3 melt is thus likely to be accompanied with the formation of triculster, in addition to a reduction in nonbridging oxygens. The pressure-induced increase in the fraction of oxygen triclusters >20 GPa would result in enhanced density, viscosity, and crystal-melt partitioning, and reduced element diffusivity in the MgSiO3 melt toward deeper part of the Earth's lower mantle.</P>

Specific surface area measurement after organic matter removal and its implication for the calculation of weathering rates for critical loads of terrestrial

( Bum Han Lee ),( Sang Jin Yeo ),( Soo Jin Kim ) 한국광물학회 2000 한국광물학회.한국암석학회 공동학술발표회 논문집 Vol.2000 No.-

Mineralogy and the exposed surface area are most important factors for calculating the weathering rates of soils. But there has not been known an accurate method for calculating the weathering rate, because soils are mixtures of inorganic and organic materials of various size distributions and structures. Surface area of minerals plays an important role in most of programs for calculating the weathering rates or critical loads. The BET measurement is recommended for the measurement of specific surface area in most of programs. But the BET values measured without organic matter removal are in fact those for all the N2-adsorbed surface areas, including the surfaces covered and aggregated with organisms. Surface areas occupied by organisms are assumed to be more reactive to weathering by organic activities. Therefore, the BET surface area difference before and after organic removal depicts the area occupied by organisms. The present study shows that the BET values after organic matter removal using H202 are lager than those without removal by 1.39 - 6.32m2/g. This means that the BET measurement without organic removal excludes the reactive area occupied by organisms and that the area occupied by organisms in soils is much lager than expected. Therefore, specific surface area measurement for calculating the weathering rates of minerals in soils should be made for both samples before and after organic matter removal.

Rapid Collection of Opinions from Healthcare Professionals in Multiple Institutions Using Short Message Service and Google Forms

Lee, Wonwoong,Shin, Soo-Yong,Seo, Dong-Woo,Sohn, Chang Hwan,Ryu, Jeong Min,Lee, Jae Ho,Kim, Won Young,Oh, Bum Jin,Hong, Sung Ok,Lim, Kyoung Soo Korean Society of Medical Informatics 2017 Healthcare Informatics Research Vol.23 No.2

Letter to the Editor : Melasma Showing Response to Combination Therapy with Oral Tranexamic Acid and the Q-Switched Nd:YAG Laser

( Bum Joon Ko ),( Ga Hee Jung ),( Yung Lip Park ),( Jong Suk Lee ),( Kyu Uang Whang ),( Sung Yul Lee ) 대한피부과학회 2014 대한피부과학회지 Vol.52 No.10

Melasma is a relatively common skin disorder associated with dark, brown, symmetrical patches of hyperpigmentation involving the sun-exposed areas of the face. While various treatments are currently being used, there is no treatment regarded as entirely satisfactory1,2. Recently, the low-fluence 1064 nm Q-switched Nd:YAG (QSNY) laser has bee shown to be an effective and safe treatment option for patients with melasma1. Additionally, topical, intralesional tranexamic acid administration has been reported to improve clinical efficacy in melasma treatment2. Therefore, we attempted to treat patients with melasma using oral tranexamic acid and QSNY laser combination therapy. Two female patients, aged 38 and 43 years (Fitzpatrick skin type IV), were observed to have symmetric, multi-size, brown-colored patches on the malar area that had onset several weeks prior to examination (Fig. 1A, 2A). They both had normal menstruation with no significant past medical history. They were diagnosed with melasma based upon clinical appearance. The severity of the melasma was assessed using the modified Melasma Area and Severity Index (mMASI), with scores of 7.5 and 7.8. We began to treat for melasma with a combination of oral tranexamic acid (500 mg twice daily) and once-weekly use of the QSNY laser (Revlite®, HOYA ConBio, USA) set at 1,064 nm wavelength, 8 mm spot size, and 2.8 J/cm2. After 12 weeks, their melasma lesions greatly improved without complications, and mMASI scores decreased to 4.8 and 5.0 (Fig. 1B, 2B). Melasma may be treated using various therapeutic methods including topical or oral agents, chemical peeling, or laser treatment. These methods have been used alone or together as a form of combination therapy1. However, a satisfactory treatment regimen has yet to be found for patients with melasma and dark skin. QSNY treatment is based on photothermal and photomechanical interactions induced by selective photothermolysis. The 1064 nm QSNY laser can cause dermal and epidermal melanosome rupture in melanocytes and destructionof dermal melanophages1. Recently, the use of the 1064 nm QSNY laser has become increasingly referred to as “laser toning” for melasma in Asian countries. Although multiple passes of the low-fluence laser are delivered to obtain clinical improvement with less downtime in laser toning, it is possible to cause painful swelling and post- inflammatory hyper- or hypo-pigmentation1. Tranexamic acid is used as a hemostatic agent due to its selective antifibrolytic action. More recently, tranexamic acid has been used in the treatment of hyperpigmentation. Ultraviolet irradiation induces plasminogen activator synthesis and increases plasmin activity in keratinocytes and stimulates the release of arachidonic acid. Free arachidonic acid stimulates melanogenesis via its metabolite, prostaglandin. Tranexamic acid attaches to the lysine-binding site of plasminogen activator, which inhibits the plasminogen/ plasmin system. This results in interference with keratinocyte- melanocyte interactions and lower arachidonic acid and prostaglandin levels2,3. This mechanism down-regulates the tyrosine activity of melanocytes, resulting in improvement in patients with melasma hyperpigmentation lesions. Karn et al.4 reported that the addition of oral tranexamic acid provided rapid and sustained improvement in the treatment of melasma as compared to routine topical therapies only. Histologically, tranexamic acid decreases the epidermal pigmentation associated with melasma and also reverses melasma-related dermal changes, such as increased numbers of vessels and mast cells3. Side effects of tranexamic acid, such as gastrointestinal discomfort and hypomenorrhea, were observed in 5.4-8.1%of patients in 1 study; however, no severe complications were found until 6 months had passed, and the recurrence of melasma was observed in only a small portion of treated patients3. Currently, there are no long-term follow-up studies regarding this combination therapy. A 4-week follow-up study showed that in combination with low- fluence QSNY, oral tranexamic acid enhanced the efficacy of laser treatments, and reduced the risk of laser side effects by allowing for longer laser treatment intervals5. However, the treatment of melasma remains challenging due to its frequent recurrence, even after successful removal of lesions. Therefore, a long-term follow-up study of ongoing treatment is needed.We observed improvement in our patients with melasma after oral tranexamic acid and QSNY laser treatment. Therefore, we suggest that combination therapy using tranexamic acid and the QSNY laser should be considered as an effective modality for the treatment of melasma.