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.

Predicting Pathological Complete Regression with Haematological Markers During Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer

LEE, JOO HO,SONG, CHANGHOON,KANG, SUNG-BUM,LEE, HYE SEUNG,LEE, KEUN-WOOK,KIM, JAE-SUNG Potamitis Press 2018 Anticancer research Vol.38 No.12

The role of rhFGF-2 soaked polymer membrane for enhancement of guided bone regeneration

Lee, Sang-Hoon,Park, Young-Bum,Moon, Hong-Seok,Shim, June-Sung,Jung, Han-Sung,Kim, Hyung Jun,Chung, Moon-Kyu Informa UK (TaylorFrancis) 2018 Journal of Biomaterials Science. Polymer Edition Vol. No.

<P>The purposes of this study are to confirm the role of Fibroblast Growth Factor-2 (FGF-2) in bone regeneration by adding various concentrations of FGF-2 to the collagen membrane and applying it to the Biphasic Calcium Phosphate (BCP) bone graft site for guided bone regeneration, to explore the potential of collagen membrane as FGF-2 carrier, and to determine the optimum FGF concentration for enhancement of bone regeneration. Four bone defects of 8mm in diameter were created in 18 New Zealand rabbit calvaria. After BCP bone graft, graft material was covered with collagen membranes adding various concentration of FGF-2. The concentration of FGF-2 was set at 1.0, 0.5, 0.1mg/ml, and same amount of saline was used in the control group. To confirm the bone regeneration over time, six New Zealand rabbits were sacrificed each at 2, 4, and 12weeks, and the amounts of new bone and residual bone graft material were analyzed by histologic and histomorphometric analysis. Qualitative analyses are also conducted through immunohistochemistry, Tetrate-resistant acid phosphatase (TRAP) stain and Russell-Movat pentachrome stain. As the healing period increased, the formation of new bone increased and the amount of residual graft material decreased in all experimental groups. Immunohistochemistry, TRAP staining and pentachrome staining further showed that the addition of FGF-2 promoted bone regeneration in all experimental groups. It was also confirmed that polymer collagen membrane can be used as a useful carrier of FGF-2 when enhanced early stage of new bone formation is required.</P>

Genetic Relationships among Multiple Strains of the Genus Tetraselmis Based on Partial 18S rDNA Sequences

Lee, Hye-Jung,Hur, Sung-Bum The Korean Society of Phycology 2009 ALGAE Vol.24 No.4

Molecular genetic tools are widely used to learn more about the identical characterization of obscure microalgal strains. At the Korea Marine Microalgae Culture Center (KMMCC), the authors deduced the genetic relationship of 41 strains of the genus Tetraselmis by analysing a small subunit ribosomal DNA (18S rDNA) sequences. Forty-one strains were seperated into five groups, which showed over a 98-99% similarity to Tetraselmis striata or Tetraselmis sp. Tsbre. Also, 13 strains among them had an identical genotype to Tetraselmis striata while 5 strains had with Tetraselmis sp. Tsbre, respectively. The mean size of each strain generally showed the tendency of different variation according to the groups.

Post-Stenotic Recirculating Flow May Cause Hemodynamic Perforator Infarction

Bum Joon Kim,Hojin Ha,Hyung Kyu Huh,Guk Bae Kim,Jong S. Kim,Namkug Kim,Sang-Joon Lee,Dong-Wha Kang,Sun U. Kwon 대한뇌졸중학회 2016 Journal of stroke Vol.18 No.1

Background and Purpose The primary mechanism underlying paramedian pontine infarction (PPI) is atheroma obliterating the perforators. Here, we encountered a patient with PPI in the post-stenotic area of basilar artery (BA) without a plaque, shown by high-resolution magnetic resonance imaging (HR-MRI). We performed an experiment using a 3D-printed BA model and a particle image velocimetry (PIV) to explore the hemodynamic property of the post-stenotic area and the mechanism of PPI. Methods 3D-model of a BA stenosis was reconstructed with silicone compound using a 3D-printer based on the source image of HR-MRI. Working fluid seeded with fluorescence particles was used and the velocity of those particles was measured horizontally and vertically. Furthermore, microtubules were inserted into the posterior aspect of the model to measure the flow rates of perforators (pre-and post-stenotic areas). The flow rates were compared between the microtubules. Results A recirculating flow was observed from the post-stenotic area in both directions forming a spiral shape. The velocity of the flow in these regions of recirculation was about one-tenth that of the flow in other regions. The location of recirculating flow well corresponded with the area with low-signal intensity at the time-of-flight magnetic resonance angiography and the location of PPI. Finally, the flow rate through the microtubule inserted into the post-stenotic area was significantly decreased comparing to others (P<0.001). Conclusions Perforator infarction may be caused by a hemodynamic mechanism altered by stenosis that induces a recirculation flow. 3D-printed modeling and PIV are helpful understanding the hemodynamics of intracranial stenosis.

Nail Grinding and Topical Efinaconazole Could be a Good Therapeutic Option for Onychogryphosis Caused by Onychomycosis

( Sang-hyeon Won ),( Kihyuk Shin ),( Woo-il Kim ),( Min-young Yang ),( Won-ku Lee ),( Hoon-soo Kim ),( Hyun-chang Ko ),( Byung-soo Kim ),( Moon-bum Kim ) 대한피부과학회 2020 대한피부과학회지 Vol.58 No.3

Incidental Left Ventricular Thrombus Visualized by Cardiac Magnetic Resonance Imaging with a Normal Left Ventricular Systolic Function

Sang Mi Ro1,Sung Ho Her,Sol Mi Huo,Kuhn Park,Jong Bum Kwon,Dong Jae Lee,Hyun Jin Noh 조선대학교 의학연구원 2015 The Medical Journal of Chosun University Vol.40 No.3

Left ventricular (LV) thrombi may be caused by various conditions, particularly myocardial infarction. In most cases, LV thrombus occurs in patients with a significantly reduced ejection fraction. A LV thrombus is extremely rare in patients with normal LV function. We report a case of LV thrombus initially detected on transthoracic echocardiography and confirmed using cardiac magnetic resonance imaging in a patient with normal LV wall motion. We highlight the rarity of this condition and the usefulness of cardiac magnetic resonance imaging in the diagnosis of LV thrombus.