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.

유량지속곡선을 이용한 한강수계 총량관리 단위유역 오염기여도 분석

이한필 ( Han Pil Rhee ),최재호 ( Jaeho Choi ),이성준 ( Yong Seok Kim ),김용석 ( Sung Jun Lee ),황하선 ( Ha-sun Hwang ) 한국물환경학회 2017 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2017 No.-

류마티스 관절염에 대한 한약의 면역학적 연구동향

최도영,이재동,백용현,이송실,유명철,한정수,양형인,박상도,유미현,박은경,박동석,Choi, Do-young,Lee, Jae-dong,Back, Yong-hyeon,Lee, Song-shil,Yoo, Myung-chul,Han, Chung-soo,Yang, Hyung-in,Park, Sang-do,Ryu, Mi-hyun,Park, Eun-kyung,Park, 대한침구의학회 2004 대한침구의학회지 Vol.21 No.4

Objective : Rheumatoid arthritis is an autoimmune disease that pathogenesis is not fully understood and one of the most intractable musculoskeletal diseases. The concern in the immunopathogenesis of rheumatoid arthritis has been increased since 1980's and many immunotherapeutic agents including disease-modifying antirheumatic drugs (DMARDs) were developed and became the mainstay of treatment of rheumatoid arthritis. However, the cure of the disease has hardly been achieved. In oriental medicine, rheumatoid arthritis is related to Bi-Zheng(痺證), that presents pain, swelling, andlor loss of joint function as major clinical manifestations, and also known to be deeply involved in suppression of immune function related to weakness of Jung-Ki(正氣). The herbal medicine, empirically used, could be a potential resource of development of new immunotherapeutic agents for rheumatoid arthritis. Methods : We developed a search strategy using terms to include "rheumatoid arthritis and herbal medicine" combined with "Chinese medicine" and/or "Oriental medicine". The search was focused on experimental studies of herbal medicine (January 1999 to May 2004), which is known to have effects on immune function of patients with rheumatoid arthritis. Computerized search used Internet databases including KISS and RISS4U (Korea), CNKI (China), MOMJ (Main Oriental Medicine Journal, Japan), and PubMed. The articles were selected from journals of universities or major research institutes. Results : The literature search for experimental studies on effects of herbal medicine on immunity of rheumatoid arthritis retrieved a total of 21 articles (Korea; 8, China ; 12, Japan ; 1). Of 21 articles, 10 were related to single-drug formula, 2 to drug interaction, and 9 to multi-drug formula. Single-drug formula was mainly used for aqua-acupuncture and researches on active components. Studies of drug interaction emphasized harmony of Ki-Hyul(氣血) and balance of Han-Yeul(寒熱). Multi-drug regimen was mainly found among formulas for Bo-Ki-Hyul(補氣血) and Bo-Sin(補腎). Conclusion : Studies on rheumatoid arthritis were performed both in vitro and in vivo in vitro study, LPS-stimulated splenocytes and synoviocytes were treated with herbal medicine, resulting in proliferation and activation of immune cells and suppression of cytokine activities in vivo study CIA animal model demonstrated that herbal medicine decreased antibody production and improved function of immune cells. In cellular and molecular study herbal medicine showed profound effects on the level of mRNA expression of certain cytokines related to immune function. This study revealed that herbal medicine has significant immune modulatory action and could be used for recovery of immune dysfunction of rheumatoid arthritis patients.

강원도 화천군 수달(Lutra lutra) 서식지의 식생 구조

서형수 ( Hyung Soo Seo ),신영섭 ( Young Seob Shin ),이경은 ( Kyung Eun Lee ),김윤미 ( Yoon Mi Kim ),전미나 ( Mina Jeon ),남택우 ( Taek Woo Nam ),한성용 ( Sung Yong Han ),정연숙 ( Yeonsook Choung ) 한국하천호수학회 2014 생태와 환경 Vol.47 No.special

In order to determine whether vegetation would be one of the factors for the selection of otter home range, vegetation structure and other potential factors were studied in Hwacheon, Korea. Thirteen sites, otter’s activity found and not found, were investigated in North Han River and connected tributary streams of Hwacheon-gun. Three types of vegetation were classified by cluster analysis, which is short grass, tall grass and shrub type. Vegetation zone of each channel is composed of either one type, or mosaic of tall grass and shrub type. Short grass type is common in Lake Paro and upper North Han-river where water level is highly variable throughout a year. Therefore, annual species such as Persicaria nodosa, Fimbristylis dichotomam and Chenopodium ficifolium are the most dominant. Shrub type is common at the downstream sites of Jichon stream and along mainstream of North Han River down Lake Paro. A shrub species, Salix koreensis, is the most common. Tall grass type is dominant occupying the most vegetation zone of the tributary channels. Phragmites japonica is absolutely dominant. Due to its dense cover, a few plant species are co-existed. Otter activity was found in all three vegetation types and no marked activity was found at some sites of tall grass type. There is no difference in species composition and physiognomy between tall grass sites with and without otter activity, while it shows significant difference in fish availability between two groups. Overall we found that home range of otters in the region is along the mainstream and downstream of tributary streams with high fish availability in all vegetation types and in various human activity levels.

초등 교과교육학의 성격과 내용구조 연구

유한구(Han Ku Ryu),장성모(Sung Mo Chang),송광용(Kwang Yong Song),조주연(Joo Yun Cho),이학주(Hak Ju Lee) 한국초등교육학회 1997 초등교육연구 Vol.11 No.1

이 연구는 교과교육과 교과교육학의관계, 그리고 교과교육학과 교육학의 관계등을 분석하고, 그 결과를 토대로 하여 초등학교 교과교육과 교육대학 교과교육학 교육의 실제를 정확히 이해하고 그 발전 방향을 탐색하기 위한 것이다. 일반적으로, 교과교육학은 교육학에서 제시하고 있는 교육과정의 구성및 교육방법상의 일반 원리를 교과교육이라는 특수한 사태에 적용하는 과정에 관심을 두는 이론으로 간주되고 있다. 이 관점에 의하면, 교과교육학은 교육학의 일반적 원리에 따라 교과교육이라는 특수한 맥락에 처방을 내리기 위한 것으로 파악된다. 이 관점을 교과와 그것을 가르치는 교사의 삶을 사실상 별개의 것으로 분리하는 것이며, 그와 동일한 이유에서 교과교육학과 교과교육학자의 삶 또한 별개의 것임을 전제하는 것이다. 그러나 교과교육과 교과교육학, 그리고 교과교육학과 교육학의 관계는 이론에서 실제로 나아가는 앞의 방향과는 정반대 방향에서도 이해될 수 있다. 이 관점에 의하면, 교과교육학은 교과교육 실제에 처방을 내리기 위한 것이 아니라 그 실제를 기술하고 정당화하기 위한 것으로 파악된다. 교과교육과 교과교육학의 관련이 이렇게 파악될 때, 교과 교육학은 교사나 교과교육학자에게 자신이 지금 하는 일이 자신의 삶과 결코 무관한 것이 아니라는 믿음을 심어 주게 되며, 나아가 그들 자신이 참여하고 있는 초등학교나 교육대학의 교육실제를 기술하거나 정당화하려고 할 때 반드시 필요한 개념적 도구를 제공해 줄 수 있게 된다. 바로 여기에 교과교육학에 관한 종래의 접근과는 구분되는 새로운 접근방식이 요구되는 이유가 있다. The purpose of this study is threefold: The first is to analyse the relations between subject education and subject pedagogy, and between subject pedagogy and general pedagogy. The second is, based on the analysis result, to have the precise understanding of teaching various subjects in the elementary school, and of teaching subject pedagogy in the university of education. The third is to search for the desirable direction of developing the elementary education and the teacher education. Subject pedagogy is usually defined as a theory which is interested in the process of applying pedagogical principles regarding curriculum organization and teaching methods to specific teaching situations, that is, subject education situations. However, this definition has a limitation, because it assumes that a subject and the teacher's life who teaches the subject are separated from each other, and that subject pedagogy and the scholar who studies subject pedagogy are also separated. The relationship between subject teaching and subject pedagogy, and between subject pedagogy and general pedagogy can be understood with quite different viewpoint. This new viewpoint, which is the major discussion matter of this study, assumes that subject pedagogy is never separated from the life of subject teacher/subject pedagogist. This viewpoint will reveal the theoretical features of subject pedagogy better, and give us new meaning on the life of teachers/subject pedagogists. The subject pedagogy in the correct sense should provide teachers/pedagogists with the conceptual instrument based on the new viewpoint. This conceptual instrument will make teachers/pedagogists be able to describe, explain, and validate their own educational practice-such as the content structure of each subject-in the elementary school or the university of education.

Cyanoacrylate injection versus band ligation for bleeding from cardiac varices along the lesser curvature of the stomach

( Sang Jung Park ),( Yong Kwon Kim ),( Yeon Seok Seo ),( Seung Woon Park ),( Han Ah Lee ),( Tae Hyung Kim ),( Sang Jun Suh ),( Young Kul Jung ),( Ji Hoon Kim ),( Hyunggin An ),( Hyung Joon Yim ),( Jae 대한간학회 2016 Clinical and Molecular Hepatology(대한간학회지) Vol.22 No.4

Background/Aims: Practice guidelines recommend endoscopic band ligation (EBL) and endoscopic variceal obturation (EVO) for bleeding from esophageal varices and fundal varices, respectively. However, the optimal treatment for bleeding from cardiac varices along the lesser curvature of the stomach (GOV1) remains undefined. This retrospective study compared the efficacy between EBL and EVO for bleeding from GOV1. Methods: Patients treated by EBL or EVO via cyanoacrylate injection for bleeding from GOV1 were enrolled. Patients diagnosed with hepatocellular carcinoma or treated with endoscopic injection sclerotherapy were excluded. Results: The study included 91 patients treated for bleeding from GOV1. The mean age was 56.3±10.9 years (mean±SD), and 78 of them (85.7%) were men. Overall, 51 and 40 patients were treated with EBL and EVO, respectively. A trend for a higher hemostasis rate was noted in the EVO group (100%) than in the EBL group (82.6%, P=0.078). Varices rebled in 15 patients during follow-up. The rebleeding rate was significantly higher in the EBL group than in the EVO group (P=0.004). During follow-up, 13 patients died (11 in the EBL group and 2 in the EVO group); the survival rate was marginally significant between two groups (P=0.050). The rebleeding-free survival rate was significantly higher in the EVO group than in the EBL group (P=0.001). Conclusions: Compared to EBL, EVO offered significantly lower rebleeding rates, significantly higher rebleeding-free survival rates, and a trend for higher hemostasis and survival rates. EVO appears to be the better therapeutic option for bleeding from GOV1. (Clin Mol Hepatol 2016;22:487-494)

Impact of hyperglycemia on survival and infection in patients with metastatic colorectal cancer

( Yong Joo Hong ),( Hye Suk Han ),( Jae Hee Han ),( Sung Nam Lim ),( Hyung Jin Choi ),( Hyun Jung Jeon ),( Tae Keun Oh ),( Ki Hyeong Lee ),( Seung Taik Kim ) 대한내과학회 2012 대한내과학회 추계학술발표논문집 Vol.2012 No.1

Growth and characterization of Mg<i> _x </i>Zn₁ ₋ <i> _x </i>O films grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy

Han, Seok Kyu,Lee, Hyo Sung,Kim, Dong-Yeob,Hong, Soon-Ku,Ahn, Byung Jun,Song, Jung-Hoon,Jeong, Myoungho,Lee, Ju Ho,Lee, Jeong Yong,Yao, Takafumi Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.623 No.-

<P><B>Abstract</B></P> <P>We report on the structural and optical properties of non polar a-plane Mg<I> <SUB>x</SUB> </I>Zn<SUB>1</SUB> <SUB>−</SUB> <I> <SUB>x</SUB> </I>O (0⩽ <I>x</I> ⩽0.57) films on r-plane sapphire substrates grown by plasma-assisted molecular beam epitaxy. Reflection high energy electron diffraction (RHEED) revealed a formation of cubic MgO phase when an Mg concentration increases. Room temperature (RT) photoluminescence (PL) and transmission electron microscopy consistently revealed the formation of cubic MgO phase from the Mg<SUB>0.21</SUB>Zn<SUB>0.79</SUB>O film. The Mg<SUB>0.11</SUB>Zn<SUB>0.89</SUB>O film showed a band edge emission at ∼360nm, which is a shorter wavelength than the ZnO (∼373nm), from the RT PL measurements. Photoluminescence excitation (PLE) measurements at RT showed that band-gap energies of Mg<I> <SUB>x</SUB> </I>Zn<SUB>1</SUB> <SUB>−</SUB> <I> <SUB>x</SUB> </I>O films could be tuned up to ∼4.65eV (∼270nm) although cubic MgO phase were mixed for high Mg concentration. For the single phase wurtzite MgZnO film, band-gap energy of 3.48eV was obtained from the Mg<SUB>0.11</SUB>Zn<SUB>0.89</SUB>O film.</P>

The comparative study in use of Non-steroid anti-inflammatory drugs effects on bone mineral density between Rheumatoid arthritis and Osteoarthritis

( Sang Yeob Lee ),( Yong Jun Kim ),( Sang Hyeon Kang ),( Dong Yeol Lee ),( Duk Song Cho ),( Kyong Han Kim ),( Won Tae Chung ),( Sung Won Lee ) 대한내과학회 2011 대한내과학회 추계학술발표논문집 Vol.2011 No.1

The NSAIDs and celecoxib in the treatment of rheumatoid arthritis and osteoarthritis had been used for a long time.However, in vitro animal model, these drugs had been reported that inhibit PGE2 and suppressed the PGE2 production by osteoblasts is involved in the mechanism of bone resorption recently. so the influence of NSAIDs and celecoxib on the patient`s actual bone density was studied. We enrolled 445 patients (Rheumatoid arthritis 256, Osteoarthritis 189), and investigated an use of NSAIDs effects on bone mineral density. All patients included in the study of the patients receiving bisphosphonate. To evaluation of bone mineral density, the Hologic QDR dual energy x ray absorptiometry was regularly performed at intervals of one year, but one-year intervals to observe changes in bone mineral density thought to be too short observation period, two-year trend of change in bone mineral density measured. The NSAIDs administered in each of the patients and the NSAIDs have adverse effects on patients were treated on behalf of celecoxib. Both patients with rheumatoid arthritis, the average steroid prednisolone 10 mg / day was in use, the NSAIDs of the 140 people, the celecoxib was used the 116 patients. The patients with osteoarthritis did not use steroids, NSAIDs was used 106 patients, celecoxib was used 83 patients. In patients with rheumatoid arthritis, the average disease duration of 8 years, the average age is 70 years old and received treatment with NSAIDs or celecoxib period was an average of 4 years, in patients with degenerative arthritis, 7.8 years, 69 years old, was 3 years. During the observation period of the average change of the T-score showed increased in both groups. Patients with rheumatoid arthritis, lumbar portion of 0.11, hip portion 0.01, and patients with degenerative arthritis, lumbar portion 0.15, hip portion 0.06, were increased. Statistically in the groups with the administration of NSAIDs or celecoxib on bone mineral density did not affect. However, The use of bisposphonate was significant (p<0.05). In conclusion, the treatment of NSAIDs or celecoxib did not affect bone mineral density in rheumatoid arthritis patients or patients with degenerative arthritis.

Microscale loop-mediated isothermal amplification of viral DNA with real-time monitoring on solution-gated graphene FET microchip

Han, Dawoon,Chand, Rohit,Kim, Yong-Sang Elsevier 2017 Biosensors & bioelectronics Vol.93 No.-

<P><B>Abstract</B></P> <P>Rapid and reliable molecular analysis of DNA for disease diagnosis is highly sought-after. FET-based sensors fulfill the demands of future point-of-care devices due to its sensitive charge sensing and possibility of integration with electronic instruments. However, most of the FETs are unstable in aqueous conditions, less sensitive and requires conventional Ag/AgCl electrode for gating. In this work, we propose a solution-gated graphene FET (SG-FET) for real-time monitoring of microscale loop-mediated isothermal amplification of DNA. The SG-FET was fabricated effortlessly with graphene as an active layer, on-chip co-planar electrodes, and polydimethylsiloxane-based microfluidic reservoir. A linear response of about 0.23V/pH was seen when the buffers from pH 5–9 were analyzed on the SG-FET. To evaluate the performance of SG-FET, we monitored the amplification of Lambda phage gene as a proof-of-concept. During amplification, protons are released, which gradually alters the Dirac point voltage (V<SUB>Dirac</SUB>) of SG-FET. The resulting device was highly sensitive with a femto-level limit of detection. The SG-FET could easily produce a positive signal within 16.5min of amplification. An amplification of 10ng/μl DNA for 1h produced a ∆V<SUB>Dirac</SUB> of 0.27V. The sensor was tested within a range of 2×10<SUP>2</SUP> copies/μl (10 fg/μl) to 2×10<SUP>8</SUP> copies/μl (10ng/μl) of target DNA. Development of this sensing technology could significantly lower the time, cost, and complications of DNA detection.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The solution-gated graphene FET (SG-FET) integrated with microchannel was fabricated. </LI> <LI> The SG-FET was used for real-time monitoring of loop-mediated isothermal amplification of DNA. </LI> <LI> Proton released during the LAMP alters the V<SUB>Dirac</SUB> of SG-FET. </LI> <LI> Viral DNA was efficiently amplified on-chip and monitored. </LI> <LI> SG-FET could analyze 10 fg/μl of DNA in just 5μl of reaction mixture. </LI> </UL> </P>