Microstructure, Tensile and Fatigue Properties of Al–5 wt.%Mg Alloy Manufactured by Twin Roll Strip Casting

Joon‑Young Heo,Min‑Seok Baek,Kwang‑Jun Euh,Kee‑Ahn Lee 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

This study investigated the microstructure, tensile and fatigue properties of Al–5 wt.%Mg alloy manufactured by twin rollstrip casting. Strips cast as a fabricated (F) specimen and a specimen heat treated (O) at 400 °C/5 h were produced andcompared. In the F specimen, microstructural observation discovered clustered precipitates in the center area, while in theO specimen precipitates were relatively more evenly distributed. Al, Al 6 (Mn, Fe), Mg 2 Al 3 and Mg 2 Si phases were observed. However, most of the Mg 2 Al 3 phase in the heat-treated O specimen was dissolved. A room temperature tensile test measuredyield strength of 177.7 MPa, ultimate tensile strength of 286.1 MPa and elongation of 11.1% in the F specimen and167.7 MPa (YS), 301.5 MPa (UTS) and 24.6% (EL) in the O specimen. A high cycle fatigue test measured a fatigue limit of145 MPa in the F specimen and 165 MPa in the O specimen, and the O specimen achieved greater fatigue properties in allfatigue stress conditions. The tensile and fatigue fracture surfaces of the above-mentioned specimens were observed, and thisstudy attempted to investigate the tensile and fatigue deformation behavior of strip cast Al–5 wt.%Mg based on the fi ndings.

제주 차귀도 연안해역 미생물 분포 및 이화학적 특성

문영건,김만철,이준백,송춘복,여인규,김종만,박근태,손홍주,최우봉,허문수 한국환경과학회 2006 한국환경과학회지 Vol.15 No.3

다변량 분석법을 이용한 소양강댐 상류 유역의 하천 수질 평가

최한규,백효선,허준영 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

The object of this study is to evaluate the factors affecting the water quality and to propose the influence of dominant factor quantitatively. The correlation analysis was performed to know the correlationship among the water quality items. As a result of partial correlation analysis, it was shown that the water quality items are affected by the rainfall item directly. The factor analysis was performed to grasp some number of factors on each point for deducing the items of similar variable characteristics. The four points were divided into different factor groups. It was grasped that NH_3-N and NO_3-N items have different variable characteristics after comparing the items. The Multiple regression analysis can decrease the number of observation. In the deduced multiple regression formula, it was shown that the rate of T-N, NH_3-N and NO_3-N in the independent variable took about 60% among all the regression formulas.

산불진화정보 관리를 위한 Mobile GIS 공간 데이터 압축기법 개발

조명희,이명보,이시영,김준범,권봉겸,허영진 한국지리정보학회 2004 한국지리정보학회지 Vol.7 No.2

최근 무선 인터넷 및 통신기술의 눈부신 발달과 LBS(location based service)개념을 기반으로 한 mobile GIS 기술 개발은 대규모 산불 발생시 정확한 현장 파악과 신속한 상황보고 뿐만 아니라 사고 예방과 분석·평가에 이르기까지 의사결정지원시스템으로 자리를 잡고 있다. 본 연구에서는 지상진화대의 정확한 위치와 이동상황을 실시간으로 파악하여 안전한 진화작업 유도 및 산불진화 환경정보를 제공을 목적으로 mobile GIS 기술 기반의 산불진화정보 관리시스템을 설계하고 네트워크 부하감소를 위하여 '.gci'라는 공간 데이터 압축기법을 개발하여 면, 선, 주기 데이터에 대하여 51~62%의 높은 압축률을 구현하였다. 따라서 대규모 산불 발생시 일어날 수 있는 안전사고를 미연에 방지하고 사고 발생시 신속한 후속조치로 안전하고 과학적인 산불진화 업무를 수행할 수 있도록 하였다. Recently GPS and mobile GIS technologies based on LBS (location based service) have played an important role as DSS (decision supporting system) for domestic forest fire extinguishment policies. In this study forest fire extinguishments information management system based on mobile GIS technique was designed to seize the exact location on wireless network so that it helps to guide the safe and efficient extinguishments affairs and provide the extinguishments environment toward ground fighting teams and the central forest government in real time. Moreover, possibly to operate this system, the foundation technologies by the name of `. gci such as the spatial data compression method, the spatial data transmission method over wireless network and the spatial analysis interface on PDA should be mainly considered. Especially, in this study the spatial data compression method having high compression rate from 51% to 62% for each polygon, line, and point data, without the loss of data was developed.

물리학 선량법을 이용한 갑상선암의 개인별 최대안전용량 I-131 치료법 개발과 유용성 평가

김정철,윤정한,범희승,제갈영종,송호천,민정준,정환정,김성민,허영준,이명호,박영규,정준기 대한핵의학회 2003 핵의학 분자영상 Vol.37 No.2

목적 : 분화갑상선암 환자에 대한 방사성옥소(I-131) 치료는 재발율과 사망률을 감소시키는 효과적인 치료법이지만, 치료용량을 증가시킴으로써 치료율을 향상시킬 수 있는지에 대해서는 아직 논란이 있다. 본 연구에서는 최대허용선량 치료법의 효용성을 검증하고자 하였다. 대상 및 방법 : 임상적 병기가 제3, 4병기이고, 6개월 이후에 I-131 전신스캔(이하 IWBS)과 혈중 thyroglobulin (이하 Tg), anti-thyroglobulin antibody (이하 ATA), 초음파검사 (이하 US) 및 F-18 FDG PET 등을 통해 치료여부를 확인할 수 있었던 58명(남:여=9:49, 평균연령 50±11세)의 유두상갑상선암 환자를 대상으로 하였다. 이중 11명은 제4병기, 47명은 제3병기였으며, 43명(남:여=4:39), 평균연령 50±11세)은 7.4 GBq 이하의 고식적인 저용량치료법으로 치료하였고, 9.25 GBq 이상의 고용량 치료를 받은 환자는 15명(남:여=5:10, 평균연령 50±12세)으로 고용량군에서 남자가 더 많았으나 연령의 차이는 없었다. 고용량군 환자 모두에서 추적용량의 방사성옥소(평균 77±3 MBq)를 경구 투여한 후 혈중 방사능소실곡선을 통해 최대허용선량(maximum permissible dose, 이하 MPD)을 계산하였으며, 7명에서는 말초혈액림프구의 중기염색체분석법에 의해 생물학적으로 MPD를 계산하였다. 14명에서는 치료용량의 방사성옥소를 투여한 후 혈중 방사능소실곡선을 통해 MPD를 계사하였다. 완전치유(complete response, 이하 CR)는 IWBS에서 병소가 없어지고, 혈중 Tg치가 1 ng/mL 이하로 감소한 경우로 정의하였으며, 부분치유(partial response, 이하 PR)는 IWBS에서 병소가 없어졌더라도 혈중 Tg, ATA치가 높거나, US 또는 PET 검사에서 병소가 남아있는 경우로 정의하였다. 치료후 IWBS에서 병소가 오히려 증가하거나 변함없는 경우는 없었다. 방사성옥소 치료에 의한 부작용은 입원기간 중 타액선이 현저하게 붓고 통증이 있거나, 구토를 심하게 하는 경우, 그리고 퇴원후 1개월째 백혈구수가 20% 이상 감소한 경우로 정의하였다. 결과 : 양 군간에 연속적인 수치변화를 비교하는 경우는 paired t-test를 이용하였으며, 대상군간 치료효과와 부작용의 비교는 chi-square test를 이용하였다. p값 0.05 미만을 통계적으로 유의한 차이로 인정하였다. 고용량군 환자 모두에서 추적용량과 치료용량의 방사성옥소 투여 후 혈액의 피폭선량은 각각 0.012±0.3 Gy, 1.66±25 Gy였으며, 방사성옥소 투여 후 혈액에 전달되는 피폭선량은 추적용량보다 치료용량에서 더 많았고 (1.21: 166 rad, p<0.001), 방사성옥소 1 mCi당 혈액에 전달되는 피폭선량은 차이가 없었다(0.58±0.1 vs. 0.56±0.1 rad/37 MBq, p=0.34). 추적용량 방사성옥소 투여 후 구한 MPD는 평균 13.3±1.9 GBq (9.7 ~ 16 GBq) 이였고, 치료용량 방사성옥소 투여 후 구한 MPD는 평균 13.8±2.1 GBq (10.4 ~ 16.3 GBq)로 유의한 차이가 없었으며 (p=0.20), 두 수치간에는 유의한 상관 관계가 있었다(r=0.8, p<0.0001). 7명의 환자에서 말초혈액림프구 중기염색체 분석법으로 MPD를 측정하였는데 혈액의 피폭선량은 1.78±0.03 G였으며, 같은 환자에서 혈중 방사능소실곡선으로부터 구한 피폭선량은 1.54±0.03 G로 유의하게 낮았으나 (p=0.01), 두 측정치 간에는 유의한 상관관계(r=0.86, p=0.01)가 있었다. 저용량 치료군 43명 중 22명(51.2%)에서 완전치유를 보였고 21명(48.8%)에서는 부분치유를 보인 반면 고용량 치료군 15명 중 12명(80%)에서 완전치유를 보였고 3명(20%)에서만 부분치유를 보여 고용량 치료군에서 유의하게 높은 완전치유를 얻을 수 있었다(p=0.05). 한편 부작용 발생빈도는 저용량 치료군 43명 중 13(30.2%), 고용량 치료군 15명 중 6명(40%)로 양군간에 유의한 차이가 없었다(p=0.46). 임상적인 병기, 연령 및 성별에 따라서는 치유의 차이가 없었다(p>0.05). 결론 : 혈중소실곡선으로부터 MPD를 결정하고 이를 토대로 환자 개개인별로 적절한 선량을 선택하여 치료하는 방법은 부작용을 최소화하면서도 치료효과를 높일 수 있는 매우 유용한 치료법이며, 고위험군 분화갑상선 암 환자에게 가장 적절한 치료법이라고 사료되었다. Purpose: Radioiodine (1-131) therapy is an effective modality to reduce both recurrence and mortality rates in differentiated thyroid cancer. Whether higher doses shows higher therapeutic responses was still debatable. The purpose of this study was to validate curve-fitting (CF) method measuring maximum permissible dose (MPD) by a biological dosimetry using metaphase analysis of peripheral blood lymphocytes. Materials and Methods: Therapeutic effects of MPD was evaluated in 58 patients (49 females and 9 males, mean age 50±11 years) of papillary thyroid cancer. Among them 43 patients were treated with ≤7.4 GBq, while 15 patients with ≥9.25 GBq. The former was defined as low-dose group, and the latter high-dose group. Therapeutic response was defined as complete response when complete disappearance of lesions on follow-up 1-131 scan and undetectable serum thyroglobulin levels were found. Statistical comparison between groups were done using chi-square test. P value less than 0.05 was regarded as statistically significant. Results: MPD measured by CF method using tracer and therapeutic doses were 13.3±1.9 and 13.8±2.1 GBq, respectively (p=0.20). They showed a significant correlation (r=0.8, p<0.0001). Exposed doses to blood measured by CF and biological methods were 1.54±0.03 and 1.78±0.03 Gy (p=0.01). They also showed a significant correlation (r=0.86, p=0.01). High-does group showed a significantly higher rate of complete response (12/15, 80%) as compared to the low-dose group (22/43, 51.2%) (p=0.05). While occurrence of side effects was not different between two groups (40% vs. 30.2%, p=0.46). Conclusion: Measurement of MPD using CF method is reliable, and the high-dose 1-131 therapy using MPD gains significantly higher therapeutic effects as compared with low-dose therapy.

Effects of Heat Treatment on the Microstructures and High Temperature Mechanical Properties of Hypereutectic Al–14Si–Cu–Mg Alloy Manufactured by Liquid Phase Sintering Process

Joon-Young Heo,Jin-Han Gwon,Jong-Kwan Park,Kee-Ahn Lee 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.3

Hypereutectic Al–Si alloy is an aluminum alloy containing at least 12.6 wt.% Si. It is necessary to evenly control the primarySi particle size and distribution in hypereutectic Al–Si alloy. In order to achieve this, there have been attempts to manufacturehypereutectic Al–Si alloy through a liquid phase sintering. This study investigated the microstructures and high temperaturemechanical properties of hypereutectic Al–14Si–Cu–Mg alloy manufactured by liquid phase sintering process and changesin them after T6 heat treatment. Microstructural observation identifi ed large amounts of small primary Si particles evenlydistributed in the matrix, and small amounts of various precipitation phases were found in grain interiors and grain boundaries. After T6 heat treatment, the primary Si particle size and shape did not change signifi cantly, but the size and distributionof CuAl 2 ( θ ) and AlCuMgSi ( Q ) changed. Hardness tests measured 97.36 HV after sintering and 142.5 HV after heat treatment. Compression tests were performed from room temperature to 300 °C. The results represented that yield strength wasgreater after heat treatment (RT ~ 300 °C: 351 ~ 93 MPa) than after sintering (RT ~ 300 °C: 210 ~ 89 MPa). Fracture surfaceanalysis identifi ed cracks developing mostly along the interface between the primary Si particles and the matrix with somediff erences among temperature conditions. In addition, brittle fracture mode was found after T6 heat treatment.

An integrative process for obtaining lipids and glucose from <i>Chlorella vulgaris</i> biomass with a single treatment of cell disruption

Heo, Young Mok,Lee, Hanbyul,Lee, Changsu,Kang, Juwon,Ahn, Joon-Woo,Lee, Young Min,Kang, Kyu-Young,Choi, Yoon-E,Kim, Jae-Jin Elsevier 2017 Algal research Vol.27 No.-

<P><B>Abstract</B></P> <P>To examine the possibility of better utilizing <I>Chlorella vulgaris</I> biomass including its carbohydrate as well as lipid contents, it was investigated whether cell disruption for lipid extraction could render the remaining microalgal residue (MR) suitable for enzymatic saccharification, possibly due to the disruption of cell wall structures. The <I>C. vulgaris</I> biomass was subjected to lipid extraction with different cell disruption methods (autoclaving, microwave irradiation, osmotic shock, and sonication), and recovered MRs were hydrolyzed using an enzyme produced from <I>Trichoderma koningiopsis</I> KUC21269 in this study. The enzyme was produced on-site with a highly simplified medium of barley straw, an agricultural byproduct. As a result, the saccharification rate of MR treated with microwave was more than twice that of the control group, and microwave irradiation appeared to be a promising method for both lipid extraction and subsequent saccharification. Our results suggested that both lipids and carbohydrates in <I>C. vulgaris</I> can be utilized by applying proper cell disruption method and a fungal enzyme produced on-site using an agricultural byproduct, respectively. This study revealed the high potential of <I>C. vulgaris</I> as an integrated bio-resource for both lipids and glucose, which can be converted to biodiesel and bioethanol, providing clues for overcoming hurdles in economically feasible biofuel production using microalgae.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Both lipids and glucose in <I>C. vulgaris</I> could be obtained with a single treatment. </LI> <LI> Cell disruption for lipid extraction could also damage cell wall structures. </LI> <LI> Lipid-extracted residues were hydrolyzed using a fungal enzyme produced on-site. </LI> <LI> Saccharification rate was more than doubled by microwave irradiation. </LI> <LI> Microwave irradiation enhanced the bioaccessibility of cellulose in the cell walls. </LI> </UL> </P>

Coffee Break : The Preliminary Report on the Bronchoscopy-assisted Percutaneous Dilatational Tracheostomy in Critically Ill Patients (초)

Young Jae Cho,Young Sik Park,Jin Woo Lee,Hyo Jeong Lim,Eun Young Heo,Jae Joon Yim,Seok Chul Yang,Young Whan Kim,Sung Koo Han,Chul Gyu Yoo 대한결핵 및 호흡기학회 2010 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.110 No.-

The efficacy and safety of Telbivudine compared with Lamivudine in Korean patients with chronic hepatitis B

( Young Myoung Moon ),( Seong Gyu Hwang ),( Boo Sung Kim ),( Kyu Sung Rim ),( Mong Cho ),( Dong Joon Kim ),( Joon Yeol Han ),( Young Seok Kim ),( Ho Soon Choi ),( Sang Hoon Ahn ),( Jeong Heo ) 대한간학회 2007 Clinical and Molecular Hepatology(대한간학회지) Vol.13 No.3(S)

Structural basis for the selective inhibition of JNK1 by the scaffolding protein JIP1 and SP600125

Heo, Yong-Seok,Kim, Su-Kyoung,Seo, Chang Il,Kim, Young Kwan,Sung, Byung-Je,Lee, Hye Shin,Lee, Jae Il,Park, Sam-Yong,Kim, Jin Hwan,Hwang, Kwang Yeon,Hyun, Young-Lan,Jeon, Young Ho,Ro, Seonggu,Cho, Joon Wiley (John WileySons) 2004 The EMBO journal Vol.23 No.11

<P>The c-jun N-terminal kinase (JNK) signaling pathway is regulated by JNK-interacting protein-1 (JIP1), which is a scaffolding protein assembling the components of the JNK cascade. Overexpression of JIP1 deactivates the JNK pathway selectively by cytoplasmic retention of JNK and thereby inhibits gene expression mediated by JNK, which occurs in the nucleus. Here, we report the crystal structure of human JNK1 complexed with pepJIP1, the peptide fragment of JIP1, revealing its selectivity for JNK1 over other MAPKs and the allosteric inhibition mechanism. The van der Waals contacts by the three residues (Pro157, Leu160, and Leu162) of pepJIP1 and the hydrogen bonding between Glu329 of JNK1 and Arg156 of pepJIP1 are critical for the selective binding. Binding of the peptide also induces a hinge motion between the N- and C-terminal domains of JNK1 and distorts the ATP-binding cleft, reducing the affinity of the kinase for ATP. In addition, we also determined the ternary complex structure of pepJIP1-bound JNK1 complexed with SP600125, an ATP-competitive inhibitor of JNK, providing the basis for the JNK specificity of the compound.</P>