Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

대형유통상업시설 개발을 위한 소비자 선택기준에 관한 연구 -용인/분당 지역 대형백화점을 기준으로-

정문오 ( Moon Oh Jeong ),김재환 ( Jae Hwan Kim ),김용일 ( Yong Il Kim ),이상엽 ( Sang Youb Lee ) 한국부동산분석학회 2009 不動産學硏究 Vol.15 No.3

Today`s distribution market has many structures such as department stores, large discount stores, traditional markets, and internet shopping malls, and the choice variety of the consumers` purchase behavior increased. For this, this study conducted research about consumer choice criteria about department stores among many distribution market structures and consumer satisfaction in Yong-In and Bun-Dang area. The degree of importance about choice criteria for department stores in general was analyzed, and for the degree of importance items, degree of preference about the actual department stores in Yong-In and Bun-Dang area was additionally analyzed. The selection of factors for department store choice criteria was ultimately done by consulting with researchers of the previous studies and distribution specialists, and the survey was conducted from an outside survey institute, and the relative importance was evaluated by AHP method. Also, additional research was conducted on the actual consumer preference of department stores located in Bun-Dang and Yong-In area about each choice criteria item. From the analysis results, the factors that are considered in priority in choosing a department stores and actual preference of department stores were analyzed, and the consumer characteristics and new perception standard were identified.

Thermoelectric Properties of Bi2Te3 Film Processed by Electrodeposition

Lee, Kwang-Yong,Oh, Tae-Sung Research Institute of Science and Technology HONGI 2005 Hongik Journal of Science and Technology Vol.9 No.-

Thermoelectric properties of the electrodeposited Bi_(2)Te_(3) films have been investigated. Bi_(2)Te_(3) plating solution of 20 mM concentration was prepared by dissolving Bi_(2)O_(3) and TeO_(2) into 1M HNO_(3). Thermoelectric properties of the electroplated Bi_(2)Te_(3) films were changed with the film thickness, and the 40 μm-thick film exhibited Seebeck coefficient of -66 μV/K, electrical resistivity of 2.4 mΩ-cm, and power factor of 1.75x10^(-4) W/K^(2)-m. Using multilayer overhang process, the photoresist pattern to form thermoelectric legs of 30 μm depth and 100 μm diameter was successfully fabricated.

Ether-free polymeric anion exchange materials with extremely low vanadium ion permeability and outstanding cell performance for vanadium redox flow battery (VRFB) application

Cha, Min Suc,Jo, Sang Woo,Han, Seung Hui,Hong, Soo Hyun,So, Soonyong,Kim, Tae-Ho,Oh, Seong-Geun,Hong, Young Taik,Lee, Jang Yong Elsevier 2019 Journal of Power Sources Vol.413 No.-

<P><B>Abstract</B></P> <P>Ether-free poly(<I>p</I>-phenylene)-based anion exchange membrane materials with outstanding vanadium ion blocking properties are reported. The synthesized ionomers with a rigid backbone structure show small dimensional variations despite the high ion exchange capacities. Among the synthesized membranes, the QPPP-2 membrane with ion exchange capacity of 2.1 meq·g<SUP>−1</SUP> exhibits high anion (OH<SUP>−</SUP>, SO<SUB>4</SUB> <SUP>2−</SUP>, and Cl<SUP>−</SUP>) conductivity. The QPPP-2 membrane shows an extremely low diffusion coefficient (2.12 × 10<SUP>−9</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP>) for VO<SUP>2+</SUP>, which is much lower than that of Nafion 115 (2.88 × 10<SUP>−6</SUP> cm<SUP>2</SUP> min<SUP>−1</SUP>), indicating the vanadium ion blocking property of QPPP-2. Moreover, the chemical and operational stabilities of the membranes are investigated <I>via</I> ex situ soaking tests in 0.1 M VO<SUB>2</SUB> <SUP>+</SUP> solution and in situ operation tests for 100 cycles, respectively. The vanadium redox flow battery single cell assembled with the QPPP-2 membrane exhibits a coulombic efficiency of 99%, voltage efficiency of 87%, and energy efficiency of 86% during 100 cycles at 80 mA cm<SUP>−2</SUP>. The excellent chemical, morphological, and electrochemical properties of the QPPP-2 membrane make it suitable for use in vanadium redox flow battery.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AEMs are fabricated by a Ni(0)-catalyzed cross-coupling reaction. </LI> <LI> The synthesized ionomers indicated excellent dimensional and chemical stability. </LI> <LI> Ether-free polymeric AEMs showed extremely low vanadium ion cross over. </LI> <LI> The performance of developed AEM showed high EE (87%) with high capacity retention. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

부산·경남지역 사찰에서 수집된 차나무(Camellia sinensis L.)잎 형태별 분류

제순자(Je, Soon-Ja)･,이용호(Lee, Yong-Ho)･,오주성(Oh, Ju-Sung3)･,정영수(Chung, Yong-Soo)･,정대수(Chung, Dae-Soo) 한국차학회 2007 한국차학회지 Vol.13 No.1

본 시험은 부산·경남지역 사찰 주변에 자생하고 있는(또는 30년 이상 재배되어 온) 차나무를 중심으로 14개 지역을 선정하여 산지별로 차나무 잎을 채취, 수집하여 잎 형태별 특성을 조사하였다. 차나무 잎의 형태적 특성 중 엽장(葉長) (12.04㎝), 엽폭(葉幅)(4.90㎝), 엽면적(葉面積)(41.33㎝)은 사천 배방사지 차나무 잎이 가장 크게 나타났으며, 가장 작게 나타난 곳은 부산 전등사 차나무가 엽장(6.30㎝)과 엽폭(2.48㎝)이 작으며, 엽면적은 거제 봉곡사(14.80㎝) 차나무가 가장 작게 나타났다. 엽병장(葉柄長)은 밀양의 엄광사지(0.57㎝)와 사천 배방사지(0.57㎝) 차나무 잎이 가장 길게 나타났으며, 거치수(鋸齒數)는 사천 배방사지(30.13개) 차나무였으며, 엽맥수(葉脈數)는 하동 쌍계사(11.27개) 차나무로 가장 많게 나타났다. 생엽중(生葉重)과 건엽중(乾葉重)은 사천 배방사지 차나무가 생엽중(0.81 g), 건엽중(0.34 g)으로 가장 무거웠으며, 가장 작은 지역은 부산 전등사가 생엽중(0.25 g)이며, 건엽중은 전등사와 범어사(0.10 g)가 가장 가볍게 나타났다. 차나무 잎의 형질간 상관관계는 수량성을 나타내는 건엽중은 엽장, 엽폭, 엽면적, 생엽중과 고도의 유의성을 보였으며 0.8이상의 매우 높은 유의차를 보였다. 본 연구 결과 사천 배방사지 차나무가 엽장(葉長), 엽폭(葉幅), 엽면적(葉面積), 엽병장(葉柄長), 거치수(鋸齒數), 생엽무게, 건조무게 등은 전체적으로 가장 크고 무거웠으며, 엽맥수(葉脈數)는 하동 쌍계사 주변의 차나무가 가장 많았다. 자생하는 차나무의 다양한 유전적 변이를 이용하여 유용한 유전자원으로 이용한다면 우량 다수성 계통의 신품종 개발 가능성이 높을 것으로 판단되며, 금후 자생지역별로 생육환경이나 지리적 특성도 검토 분석 한다면 기능성 신품종 개발 보급에 기초 자료로서 활용성이 높을 것으로 판단된다. We collected the tea leaves from the vicinity of 14 Buddhist temple located in Busan and Gyeongnam area where wild tea trees and more than 30 year old tee trees were commonly found. The characteristics of the tea leaves were surveyed. Among those tee leaves from 14 areas, Baebangsaji (Goseong) tea leaves had the highest value of leaf length (12.04 ㎝), leaf width(4.90 cm), and leaf area (41.33 ㎝). The tea leaves of Jeondeungsa (Busan) had the lowest value of leaf length (6.30 ㎝) and leaf width (2.48 ㎝). The tea leaves of Bonggoksa (Geoje) had the lowest value of leaf area (14.80 ㎝). The longest leaf stalk length was Umgwangsaji (Miryang) tea leaves (0.57 ㎝) and Baedangsaji (Goseong) tea leaf (0.57 ㎝). The largest No. of serrate was Baedangsaji (Goseong) tea leaves (30.13) and for leaf vein was Ssanggyesa (Hadong) as a number of 11.27. The heaviest weight of fresh leaf was Baedangsaji (Goseong) tea leaf (0.81 g) and, also, the dry tea leaf of Baedangsaji (Goseong) was the heaviest (0.34 g). The lightest weight of fresh leaf was Jeondeungsa (Busan) tea leaves (0.25 g) and the lightest weight of dry leaf was Jeondeungsa. In this study, leaf length, leaf width, leaf area, leaf stalk length, No. of serrate, weight of fresh leaf and weight of dry leaf value of the leaves collected from Baedangsaji (Goseong) was generally high and The highest value of No. of leaf vein was from Ssanggyesa (Hadong).

중금속 오염 논토양에서 카드뮴의 부동화와 식물이용성에 대한 석회 시용 효과

홍창오 ( Chang Oh Hong ),김용균 ( Yong Gyun Kim ),이상몽 ( Sang Mong Lee ),박현철 ( Hyean Cheal Park ),김근기 ( Keun Ki Kim ),손홍주 ( Hong Joo Son ),조재환 ( Jae Hwan Cho ),김필주 ( Pil Joo Kim ) 한국환경농학회 2013 한국환경농학회지 Vol.32 No.1

석회시용에 의한 카드뮴의 부동화와 식물이용성 저감효과를 구명하기 위해 우리나라의 대표적인 석회비료인 소석회를 선정하여 소석회에 의한 논토양 내 카드뮴의 부동화 기작과 벼의 카드뮴 흡수특성을 조사하였다. 소석회는 토양의 pH와 음하전도를 증대시켜 카드뮴의 흡착을 증대시키는 것으로 조사되었다. 소석회의 처리량을 증가시킴에 따라 식물이 이용하기 쉬운 형태인 유효태 카드뮴과 치환성 및 carbonate 결합태 카드뮴의 함량이 유의적으로 감소하였다. 소석회를 8,000 mg/kg 과량으로 시용하였을 때 CdCO3 형태로의 침전이 가능하였을 것으로 판단되나 8,000 mg/kg 이하로 처리하였을 때 CdCO3나 Cd(OH)2 형태로의 침전은 없었던 것으로 조사되었다. 또한 토양의 pH와 음하전도는 유효태 카드뮴과치환성 및 carbonate 결합태 카드뮴의 함량과 유의한 부의상관관계를 나타내었다. 따라서 소석회에 의한 토양 내 카드뮴의 부동화는 CdCO3나 Cd(OH)2 형태로의 침전형성에 의한 것이 아니라 pH와 음하전도의 증대에 기인된 카드뮴 이온의 흡착에 의한 것으로 판단되어 졌다. 논토양의 현장조건에서 소석회의 시용에 의한 벼의 카드뮴 흡수농도 저감효과를 시험한 결과, 소석회의 시용량을 증가시킴에 따라 벼의 카드뮴 흡수농도는 유의적으로 감소하는 결과를 나타내었다. Research Article : BACKGROUND : Many studies associated with cadmium (Cd) immobilization using lime fertilizer have been conducted for several decades. However, these studies did not suggest exact mechanism of Cd immobilization using lime fertilizer and evaluated effect of lime fertilizer on Cd phytoavailability in rice paddy soil under field condition. METHODS AND RESULTS: This study was conducted to determine exact mechanism of Cd immobilization using lime fertilizer and evaluate liming effect on Cd uptake of rice in contaminated paddy soil. Ca(OH)2 was mixed with Cd contaminated arable soil at rates corresponding to 0, 1,000, 2,000, 4,000, and 8,000 mg/kg. The limed soil was moistened to paddy soil condition, and incubated at 25℃ for 4 weeks. NH4OAc extractable Cd concentration in soil decreased significantly with increasing Ca(OH)2 rate, since Ca(OH)2 markedly increased net negative charge of soil by pH increase, and decreased bioavailable Cd fractions (F1; exchangeable + acidic and reducible Cd fraction). Calculated solubility diagram indicated that Cd solubility was controlled by soil-Cd. NH4OAc extractable Cd and F1 concentration were negatively related to soil pH and negative charge. Ca(OH)2 was applied at rates 0, 2, 4, and 8 Mg/ha and then cultivated rice in the paddy soil under field condition. Cadmium concentrations in grain, straw, and root of rice plant decreased significantly with increasing application rate of Ca(OH)2. CONCLUSION(S): Alleviation of Cd phytoavailability with Ca(OH)2 can be attributed primarily to Cd immobilization due to the increase in soil pH and negative charge rather than precipitation of Cd(OH)2 or CdCO3, and therefore, Ca(OH)2 is effective for reducing Cd phytoavailability of rice in paddy soil.

Lowering Color Temperature of Y[sub 3]Al[sub 5]O[sub 12]:Ce[sup 3+] White Light Emitting Diodes Using Reddish Light-Recycling Filter

Oh, Jeong Rok,Cho, Sang-Hwan,Lee, Yong-Hee,Do, Young Rag The Electrochemical Society 2010 Electrochemical and solid-state letters Vol.13 No.1

A phase II study of S-1 and oxaliplatin (SOx) combination chemotherapy as a first-line therapy for patients with advanced gastric cancer

Oh, Sung Yong,Kwon, Hyuk-Chan,Jeong, Sang-Ho,Joo, Young-Tae,Lee, Young-Joon,hee Cho, Su,Kang, Myoung Hee,Go, Se-il,Lee, Gyeong-won,gu Kim, Hoon,Kang, Jung Hun Springer-Verlag 2012 Investigational new drugs Vol.30 No.1

IMPLEMENTATION ISSUES FOR ARITHMETIC OVER EXTENSION FIELDS OF CHARACTERISTIC ODD

Oh, Sang-Ho,Kim, Chang-Han,Kim, Yong-Tae,Park, Young-Ho Korean Mathematical Society 2003 대한수학회논문집 Vol.18 No.1

In this paper we discuss the Construction Of 3 new extension field of characteristic odd and analyze the complexity of arithmetic operations over such a field. Also we show that it is suitable for Elliptic Curve Cryptosystems(ECC) and Digital Signature Algorithm(DSA, 〔7〕) as an underlying field. In particular, our digital signature scheme is at least twice as efficient as DSA.

The risk factors of methicillin-resistant staphylococcus aureus infection in the patients with bacterial spondylitis accompaning bacteremia (초)

Sung Joon Jin,Yun Tae Chae,Hee Kyoung Choi,Bum Sik Chin,Sang Hoon Han,So Youn Shin,Chang Oh Kim,Young Goo Song,Jun Yong Choi,June Myung Kim 대한내과학회 2009 대한내과학회지 Vol.77 No.4S