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.

Change of heating value, pH and FT-IR spectra of charcoal at different carbonization temperatures

Sung Min Kwon,Jae Hyuk Jang,Seung Hwan Lee,Sang Bum Park,Nam Hun Kim 한국목재공학회 2013 목재공학 Vol.41 No.5

To understand transition characteristics from wood to charcoal, Quercus variabilis wood was carbonized at 200, 250, 300, 340, 540 and 740°C, respectively. Heating value, pH and surface property by FT-IR spectroscopy of the carbonized charcoal were investigated. Heating value and pH increased with increasing carbonization temperature from 4500 cal/g and 4.3 of the control wood to 8,000 cal/g and 9 of the charcoal carbonized at 740°C, respectively. From FT-IR spectroscopy, the peaks from O-H, C-H and C-O stretching disappeared during carbonization at 540 and 740°C. Aromatic skeletal vibration at near 1,506~1,593 cm -1 was repidly increased until 540°C. These results suggest that the chemical and physical characteristics of wood components in cell wall can be easily changed by increasing carbonization temperature and the carbonization seem to be incomplete at temperature below 540°C.

Co-expression of two heterologous lactate dehydrogenases genes in <i>Kluyveromyces marxianus</i> for <small>L</small>-lactic acid production

Lee, Jae Won,In, Jung Hoon,Park, Joon-Bum,Shin, Jonghyeok,Park, Jin Hwan,Sung, Bong Hyun,Sohn, Jung-Hoon,Seo, Jin-Ho,Park, Jin-Byoung,Kim, Soo Rin,Kweon, Dae-Hyuk Elsevier 2017 Journal of biotechnology Vol.241 No.-

<P>Lactic acid (LA) is a versatile compound used in the food, pharmaceutical, textile, leather, and chemical industries. Biological production of LA is possible by yeast strains expressing a bacterial gene encoding L-lactate dehydrogenase (LDH). Kluyveromyces marxianus is an emerging non-conventional yeast with various phenotypes of industrial interest. However, it has not been extensively studied for LA production. In this study, K. marxianus was engineered to express and co-express various heterologous LDH enzymes that were reported to have different pH optimums. Specifically, three LDH enzymes originating from Staphylococcus epidermidis (SeLDH; optimal at pH 5.6), Lactobacillus acidophilus (LaLDH; optimal at pH 5.3), and Bos taurus (BtLDH; optimal at pH 9.8) were functionally expressed individually and in combination in K. marxianus, and the resulting strains were compared in terms of LA production. A strain co-expressing SeLDH and LaLDH (KM5 La + SeLDH) produced 16.0 g/L LA, whereas the strains expressing those enzymes individually produced only 8.4 and 6.8 g/L, respectively. This co-expressing strain produced 24.0 g/LA with a yield of 0.48 gig glucose in the presence of CaCO3. Our results suggest that co-expression of LDH enzymes with different pH optimums provides sufficient LDH activity under dynamic intracellular pH conditions, leading to enhanced production of LA compared to individual expression of the LDH enzymes. (C) 2016 Elsevier B.V. All rights reserved.</P>

Responses of Nitrogen Oxide to High‐Speed Solar Wind Stream in the Polar Middle Atmosphere

Lee, Ji‐,Hee,Jee, Geonhwa,Kwak, Young‐,Sil,Hong, Sang‐,bum,Hwang, Heejin,Song, In‐,Sun,Lee, Young‐,Sook,Turunen, Esa,Lee, Dae‐,Young American Geophysical Union 2018 JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS Vol.123 No.11

Antibacterial activity of silver nanoparticles prepared by a chemical reduction method

Bum Suk Lee,Sung Min Lee,송기창 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.2

Silver nanoparticles were obtained by chemical reduction of silver nitrate in water with sodium borohydride (NaBH4) in the presence of SDS (sodium dodecyl sulfate) as a stabilizer. The synthesized silver nanoparticles were characterized by UV-vis spectroscopy (UV-vis) and transmission electron microscopy (TEM). The formation of silver nanoparticles was confirmed from the appearance of surface plasmon absorption maxima at 400 nm by UV-vis. TEM showed the spherical nanoparticles with size in 10-20 nm. The antibacterial activity of silver nanoparticles was tested by using Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coil (E. coli). The silver nanoparticles, whose bacterial activity was dependent on the aggregation degree between particles, exhibited bacterial activity against S. aureus and E. coli.

Impact of Family History on Prognosis of Patients with Sporadic Colorectal Cancer

Lee, Soo Young,Kim, Duck-Woo,Kang, Sung Il,Ihn, Myong Hoon,Oh, Heung-Kwon,Kang, Sung-Bum,Kim, Chang Hyun,Kim, Hyeong Rok,Kim, Young Jin,Ju, Jae Kyun Springer - Society of Surgical Oncology 2019 Annals of Surgical Oncology Vol.26 No.4

Situating Artificial Intelligence: The Convergence of Human Emotion and Technology in Cyberpunk SF Films

( Sung Bum Lee ) 한국영미문화학회 2015 영미문화 Vol.15 No.1

Researchers of artificial intelligence (shortly AI) question digital-binary technology to set up human-compatible technology. Since current digitized AI machinery tends to simulate abstract human intelligence, it cannot be context-sensitive. Human-compatible search models such as genetic algorithm and neural network, however, overcome the de-contextualization of digital simulation. Running counter to contextless, digital-binary, sequential procedure, they pursue contextual, bidirectional algorithm. Simply put, digital AI technology seeks a top-down, pre-set computation, whereas human-compatible AI technology aspires for a bottom-up, situation-specific computation. Acting against the de-contextualization of artificial intelligence, emotion technology is a crucial part of human-adaptable technology. For computing human inner experiences lies at the peak of the contextualization of AI technology. Affective technology maximizes a bottom-up, situation-specific computation. In my essay I approach it in light of the convergence of literature and technology. The opposition between digital AI technology and affective AI technology replays itself through the conflict between artificial intelligence and artificial feeling in cyberpunk SF movies. They explore the tension of the contextless simulation of human intelligence and situation-specific simulation of human emotion. I compare Bicentennial Man, A.I., and Terminator: Salvation with the Matrix trilogy. While the former prioritizes human complex feelings over abstract mechanic intelligence, the latter treats human emotion as a new kind of programming although being distinct from digital computing. The Matrix series do not pursue human emotion as a prerogative of humanity. Instead, the films draw parallels between human inner qualities and systemic instabilities in the Matrix. Precisely, the Matrix``s control of Neo’s affective involvements such as free will and love is the anthropocentric counterpart of autonomous variations in a system. The Matrix trilogy thematizes the artificial re-creation of human emotion itself instead of sanctifying it unconditionally. Accordingly, the Matrix trilogy displays the interdisciplinary convergence of the humanities and technology. I argue that the gradual popularity of affective technology implicates the individualization of technological control.