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.

Fibrous Plaque of the Eyelid in a Patient with Tuberous Sclerosis Responding to Everolimus

( Sung-min Park ),( Byung-soo Kim ),( Moon-bum Kim ),( Yun-jin Lee ),( Hyun-chang Ko ) 대한피부과학회 2018 Annals of Dermatology Vol.30 No.2

Comparative Analysis of Spontaneous Infectious Spondylitis : Pyogenic versus Tuberculous

Lee, Yangwon,Kim, Bum-Joon,Kim, Se-Hoon,Lee, Seung-Hwan,Kim, Won-Hyung,Jin, Sung-Won The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.1

Objective : Spondylitis is often chemotherapy resistant and requires long-term treatment. Without adequate chemotherapy, the outcome can be fatal or result in severe neurologic damage. Therefore, differentiating the etiology of spondylitis is very important, particularly in spontaneous cases. As the prevalence of tuberculosis in Korea has decreased in recent years, updated clinical research about spondylitis is warranted. Methods : From April 2010 to March 2016, data from spondylitis patients were collected retrospectively. In total, 69 patients (51 with pyogenic spondylitis and 18 with tuberculous spondylitis) were included. Clinical data, laboratory findings including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level, measurements of Cobb angles at the initial and final follow-up, and radiologic features on magnetic resonance imaging (MRI) scans were evaluated. To test differences between the pyogenic and tuberculous groups, numerical data were compared using the student's t-test and Mann-Whitney U test, and categorical data were compared using the chi-square test and Fisher's exact test. Results : The patients' mean age was 60.0 years. Male sex was slightly predominant (56.5%). There was no difference in mean age and sex between the two groups. The pyogenic group had a relatively higher proportion of immunocompromised patients. The peak CRP value was higher in the pyogenic group than in the tuberculous group (14.08 mg/dL and 8.50 mg/dL, respectively, p=0.009), whereas the ESR was not significantly different between the groups (81.5 mm/h and 75.6 mm/h, respectively, p=0.442). Radiologically, the presence of disc space sparing and vertebral body collapse differed between the groups. In the tuberculous group, the disc was more commonly preserved on contrast-enhanced MRI (50% and 23.5%, respectively, p=0.044), and vertebral body collapse was more common (66.6% and 15.7%, respectively, p<0.001). The mean length of hospitalization was longer in the pyogenic group (56.5 days and 41.2 days, respectively, p=0.001). Four mortality cases were observed only in the pyogenic group. The most commonly isolated microorganism in the pyogenic group was Staphylococcus aureus(S. aureus) (methicillin susceptible S. aureus and methicillin resistant S. aureus [MRSA] in 8 and 4 cases, respectively). Conclusion : The clinical and radiological manifestations of spontaneous spondylitis differ based on the causative organism. Pyogenic spondylitis patients tend to have a higher CRP level and a more severe clinical course, whereas tuberculous spondylitis patients present with destruction of the vertebral body with disc sparing more frequently. The presence of MRSA is increasing in community-acquired spondylitis cases.

Ethnic Differences in Intracranial Artery Tortuosity: A Possible Reason for Different Locations of Cerebral Atherosclerosis

Bum Joon Kim,이경미,Sung Ho Lee,김혁기,Eui Jong Kim,Sung Hyuk Heo,장대일,Jong S. Kim 대한뇌졸중학회 2018 Journal of stroke Vol.20 No.1

Clinical Results of Contralateral Arthroscopic Meniscectomy Performed with Unilateral Total Knee Arthroplasty: Minimum 3-year Follow-up

( Sang Jin Lee ),( Bum Sik Lee ),( Jong Min Kim ),( Seong Il Bin ) 대한슬관절학회 2015 대한슬관절학회지 Vol.27 No.2

Purpose: We assessed the clinical outcome of contralateral arthroscopic meniscectomy performed with unilateral total knee arthroplasty (TKA). Materials and Methods: From May 1999 to June 2006, 23 patients underwent unilateral total knee arthroplasty and contralateral arthroscopic meniscectomy at the same time. All patients were women and followed for at least 36 months, except 2 patients who died. For clinical assessment, range of motion of the knee joint, Hospital for Special Surgery (HSS) knee score and the Lysholm knee score were evaluated preoperatively and at the last follow-up. At arthroscopy, meniscal pathology and cartilage changes were recorded and classified according to the Outerbridge scale. Progression of osteoarthritis in the contralateral knee to subsequent TKA was also assessed. Results: The mean age of the 21 patients was 67.1 years and the mean follow-up period was 5.7 years. All of the patients were diagnosed with osteoarthritis and had Outerbridge grade 3 or 4 cartilage changes. Eight of the 21 patients had subsequent TKA at an average of 3.1 years after the index operation. The other 13 patients had no further surgery and clinical results including the HSS knee score and the Lysholm score were improved from 74.5 and 60.6 preoperatively to 90.8 and 82.4 postoperatively, respectively (p<0.001). Conclusions: Contralateral arthroscopic meniscectomy performed simultaneously with unilateral TKA produces relatively good results regardless of the presence of cartilage degeneration.

An analysis of characteristics of pigmented fungiform papillae of the tongue: single center study

( Sung-min Park ),( Tae-wook Kim ),( Hyun-joo Lee ),( Hyunju Jin ),( Hyang-suk Ryu ),( Woo-haing Shim ),( Gun-wook Kim ),( Byung-soo Kim ),( Hyun-chang Ko ),( Moon-bum Kim ),( Hoon-soo Kim ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.2

Background: Pigmented fungiform papillae of the tongue (PFPT) is a rare benign pigmentary disorder of the tongue. In dark-skinned individuals, PFPT appears to be relatively common. However, limited data exist on PFPT in Korean patients. Objectives: To investigate the clinical characteristics of PFPT in Korean patients Methods: Patients diagnosed with PFPT between 1995 and 2016 at Pusan National University Hospital were included. Clinical characteristics of PFPT, dermoscopic findings, and comorbidities were reviewed. Results: Eighteen patients diagnosed as PFPT were enrolled. Male to female ratio was 1 : 5. The mean age at diagnosis was 39.6 years (range, 8-65 years). According to Holzwanger’s classification, type I was the most common (88.9%). PFPT was commonly concomitant with pigmentary disorders including mucosal melanotic macules, Laugier-Hunziker syndrome, Melasma, and melanonychia (6/18, 33.3%). Preceding oral inflammatory lesions were found in 3 patients (16.7%), and systemic diseases and infectious diseases existed in 2 patients respectively (11.1%). Dermoscopic examination was performed in 7 patients; Pigmented border with dichotomized vessels (Rose petal pattern, 71.4%), and diffuse pigmentation (cobblestone pattern, 57.1%) were common findings. Conclusion: Our study shows PFPT can coexist with pigmentary disorder. Female predominance, concomitant pigmentary disorders of PFPT shows sex hormone or susceptibility to abnormal pigmentation may play a role in pathogenesis of PFPT.

Pattern analysis of multiple cafe-au-lait macules: comparison between neurofibromatosis type 1 and isolated multiple cafe-au-lait macules

( Sang-jin Cheon ),( Tae-wook Kim ),( Sung-min Park ),( Hyun-joo Lee ),( Hyun Ju Jin ),( Hyang-suk You ),( Woo-haing Shim ),( Gun-wook Kim ),( Hoon-soo Kim ),( Byung-soo Kim ),( Moon-bum Kim ),( Hyun- 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.2

Background: More than 6 cafe-au-lait macules (CALMs) are initial clinical sign of neurofibromatosis type 1 (NF1). However, we often encounter patients with isolated multiple CALMs without accompanying other sign of NF1. Objectives: To investigate the characteristic pattern of multiple CALMs that might be suggestive NF1. Methods: Forty patients with more than 6 CALMs who visited Pusan National University Hospitals (Busan and Yangsan) from 2011 to 2017 were enrolled in this study. Among them, 23 patients were designated as NF1 (17 patients were detected by NF1 gene mutation test and 6 patients were detected by clinical criteria). The remaining 17 patients were diagnosed as isolated multiple CALMs. We compared number, shape, and distribution of CALMs in patients with NF1 and isolated multiple CALMs. Results: Number of CALMs was higher in patients with NF1 than isolated multiple CALMs patients (20.2 vs. 17.7). Especially, proportion of typical CALMs, defined as oval shape and smooth border, was higher in NF1 than isolated multiple CALMs patients (40.44% vs. 17.27%, p=0.036). In distribution, CALMs of NF1 patients were more scattered than isolated multiple CALMs patients (affecting body segment, 4.9 vs. 2.9, p=0.002). And Facial CALMs were more common in patient with NF1 than isolated multiple CALMs (63.2% vs. 18.8, p=0.016). Conclusion: High rate of typical CALMs, scattered distribution and facial CALMs might be suggestive features of NF1.