Effect of spark plasma sintering conditions on the thermoelectric properties of (Bi_0.25Sb_0.75)₂Te₃ alloys

Lim, Sang-Soon,Kim, Ju-Heon,Kwon, Beomjin,Kim, Seong Keun,Park, Hyung-Ho,Lee, Ki-Suk,Baik, Jeong Min,Choi, Won Jun,Kim, Dong-Ik,Hyun, Dow-Bin,Kim, Jin-Sang,Baek, Seung-Hyub Elsevier 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.678 No.-

<P><B>Abstract</B></P> <P>As a field-assisted technique, spark plasma sintering (SPS) enables densification of specimens in a very short period of time compared to other sintering techniques. For high performance thermoelectric material synthesis, SPS is widely used to fabricate nanograin-structured thermoelectric materials by rapidly densifying the nanopowders suppressing grain growth. However, the microstructural evolution behavior of thermoelectric materials by SPS, another important process during sintering, has been rarely studied. Here, we explore SPS as a tool to control the microstructure by long-time SPS. Using p-type (Bi<SUB>0.25</SUB>Sb<SUB>0.75</SUB>)<SUB>2</SUB>Te<SUB>3</SUB> thermoelectric materials as a model system, we systematically vary SPS temperature and time to understand the correlations between SPS conditions, microstructural evolution, and the thermoelectric properties. Our results show that the relatively low eutectic temperature (∼420 °C) and the existence of volatile tellurium (Te) are critical factors to determine both microstructure and thermoelectric property. In the liquid-phase sintering regime, rapid evaporation of Te leads to a strong dependence of thermoelectric property on SPS time. On the other hand, in the solid-phase sintering regime, there is a weak dependence on SPS time. The optimum thermoelectric figure-of-merit (Z) of 2.93 × 10<SUP>−3</SUP>/K is achieved by SPS at 500 °C for 30 min. Our results will provide an insight on the optimization of SPS conditions for materials containing volatile elements with low eutectic temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spark plasma sintering (SPS) is used to synthesize the thermoelectric (Bi<SUB>0.25</SUB>Sb<SUB>0.75</SUB>)<SUB>2</SUB>Te<SUB>3</SUB>. </LI> <LI> Liquid phase and volatile element are a key for the microstructure and thermoelectric property. </LI> <LI> Thermoelectric figure-of-merit of 2.9 × 10<SUP>−3</SUP>/K is achieved at 500 °C for 30 min. </LI> </UL> </P>

인간포배기 배아의 효과적인 유리화 동결법의 개발을 위한 연구

이상민,이주희,이상원,이승민,윤산현,임진호,박흠대,이성구,Lee, Sang-Min,Lee, Ju-Hee,Lee, Sang-Won,Lee, Seoung-Min,Yoon, San-Hyun,Lim, Jin-Ho,Park, Huem-Dai,Lee, Seong-Goo 대한생식의학회 2003 Clinical and Experimental Reproductive Medicine Vol.30 No.3

Objective: The purpose of this study was to evaluate the survival rate of vitrified blastocyst according to the freezing vessels, equilibration time in cryoprotectant and artificial dehydration method. Methods: Human blastocysts were vitrified after loading onto the plastic straw, open-pulled straw (OPS), electron microscopy grid (EM grid) for 1.5 min or 3 min. They also were directly plunged into LN2 within 30sec. For artificial shrinkage of blastocysts, 36 gauge fine needle was pushed at the cellular junction of the trophectoderm into the blstocoele cavity until it shrank without damage of inner cell mass. Results: The survival rate of vitrified blastocysts on plastic straw, OPS, EM grid as freezing vessels were 26.7, 13.0 and 60.5%, respectively. The survival rate of EM grid was significantly higher than that of plastic straw and OPS (p<0.05). For 1.5 min equilibrium, the survival rates of early blastocyst (EB), middle blastocyst (MB) and late blastocyst (LB) were 64.4, 81.0, and 20.0% respectively. For 3 min equilibrium, the survival rates of EB, MB, and LB were 69.9, 50.0 and 57.5% respectively. The survival rates of EB and MB were significantly higher than that of LB in 1.5 min equilibrium group (p<0.05), however, the significance was not observed in 3 min equilibrium groups. In cytoplasmic shrinkage before vitrification, the survival rates of EB, MB and LB were 92.9, 100 and 75.9% respectively. The survival rate of MB was significantly higher than that of LB (p<0.05). The survival rates of vitrified blastocysts by artificial dehydration and slow-frozen blastocysts were not significantly different as 88.9 and 66.7%, respectively. Conclusion: This study showed that the vitrification of human blastocysts using EM grid and artificial dehydration is an effective method. Therefore, these methods would be an useful techniques for blastocyst cryopreservation.

Saos-2 세포에서 Doxorubicin에 의한 세포사멸 유도과정에서의 유전자 발현 변화

임정숙,배민재,백석환,김재룡,김정희,김성용 영남대학교 의과대학 2005 Yeungnam University Journal of Medicine Vol.22 No.2

Background: Doxorubicin has proved to be a useful chemotherapeutic agent especially for osteogenic sarcoma. It induces cancer cell death via apoptosis. Materials and Methods: To explore and analyze the change of gene expression during doxorubicin induced apoptosis on human osteogenic sarcoma, Saos-2 cell cDNA microarray was performed. After treatment with doxorubicin, total RNA was purified and expressed genes were investigated with a 17k human cDNA micoarray. Results: For analysis of the cDNA micoarray, the genes were filtered using the sum of the median value of Cy2 and Cy5 signal intensity of greater than 800. Expression of 264 genes was changed by more than 2 fold, and the expression of 35 genes was changed more than 3 fold after treatment with doxorubicin. The genes were primarily related to cell death, cell growth and maintenance, signal transduction, cellular component, transport, and metabolism. Conclusion: Treatment with doxorubicin induced expressional change of many genes. Some of the genes might be related with apoptosis directly or indirectly. Further study is now needed to characterize these genes.

혈액 투석 환자에서 중심정맥 협착에 대한 스텐트 삽입술 : Wallstent Placement

임대승,노상필,이유선,정승현,김보영,이정우,강정아,김정희,이민수,정준용,최시완,정진옥,성인환,이강욱,신영태 충남대학교 의과대학 의학연구소 2002 충남의대잡지 Vol.29 No.1

Stenosis of central vein is a common complication arising after percutaneous subclavian vein catheter insertion performed for temporary vascular access in chronic renal failure patients undergoing hemodialysis. There are several treatment methods for the condition like percutaneous angioplasty(PTA), stent insertion, and surgery, but recent trend is toward PTA and stents. Among the patients diagnosed with chronic renal failure from March 1993 to May 2002 and undergoing hemodialysis through AV fistula, the 14 Patients in whom central vein stenosis arose were selected for the study. A total of 28 percutaneous interventions(5 PTA and 23 stent placement) were performed, and restenosis rate and the time taken till the restenosis in de novo lesions and instant lesions were compared. All 28 cases were operated successfully. The 14 cases that received both anigioplasty and stent placement initially. (de novo lesion : 14 cases), Among the 10 cases with de novo lesion that followed up more than 1 year, 3 cases are currently undergoing hemodialysis without restenosis, and the remaining 7 cases have recurred stenosis with the mean time to restenosis of 10.9 months. In the 7 cases in whom stenosis recurred, 11 interventions were done(instent lesion: 11 cases). 4 of these were using only ballon angioplasty with 100% restenosis rate and the mean time of 3 months until restenosis. The remaining 7 cases were using both balloon angioplasty and stent placement, also with 100% restenosis rate but with the mean time of 12 months until restenosis, which was later than the group receiving only balloon angioplasty. In treating the patients with central vein stenosis, stent placement seems to be more advantageous over PTA in terms of restenosis rate and the mean duration of patency. In the case of instent lesion, inserting the stent for the second time after stenosis recurred lengthened the duration of patency compared to performing balloon angioplasty alone.

디지털 콘텐츠 산업의 공간분포 특성에 관한 연구

김성훈,임용민,이시형,홍일영 남서울대학교 2010 남서울대학교 논문집 Vol.16 No.1-1

Digital contents industry is a developing industry which is being recognized for its growth possibility. This study is intended to understand the spacial distribution of digital contents industry. To do so, spatial range of this study is set in metropolitan regions to grasp the clustered regions. To understand the clustered regions of digital contents industry, spatial cluster analysis was enforced. As a result, total of 7 clusters were formed. 7 clusters are all located in Seoul, and 4 out of 7 are concentrated in Kangnam Gu. This study grasped the characteristics of these clusters. Locational factors of each company categories, which are the cause of such characteristic, are scheduled to be researched more specifically in the future. Key Words : digital contents industry, Spatial distribution, cluster, Locational factor, Spatial clustering

東醫寶鑑 火門의 處方에 대한 分析

林承民,薛仁燦 대전대학교 한의학연구소 2001 한의학연구소 논문집 Vol.10 No.1

1.The frequency of source of prescriptions is dangyesimbub(丹溪心法), euihakibmun(醫學入門), dongwonsibseo(東垣十書), goguemeuibang(古今醫方) in sequence. 2.The classification of prescriptions by efficacy is chungyeulsahoayak(淸熱寫火藥), boumyak(補陰藥), hoalhyulguayak(活血祛瘀藥), igiyak(理氣藥), chunghwayuldamyak(淸下熱痰藥), bogiyak(補氣藥), balsanpunghanyak(發散風寒藥), balsanpungyeolyak(發散風熱藥), etc. in sequence. 3.The frequency of used medicines is hoangum(黃芩), danguy(當歸), jakyak(芍藥), insam(人蔘), saengjihoang(生地黃), bokryung(茯笭), hoangbaek(黃粕), jimo(知母), makmundong(脈門冬), chija(치子) etc. insequence. 4.The sung of used medicines is mainly hangsung(寒性), onsung(溫性), the mi(味) is gomi(苦味), sinmi(辛味), gammi(甘味) in sequence. the gwigyung(歸經) is bigyung(脾經), wigyung(胃經), simgyung(心經), etc, in sequence.

한국인에서 혈소판 당단백 Ⅱb/Ⅲa 유전자 다형성과 관동맥 성형술 후 재 협착과의 관계

이민수,이정우,김보영,임대승,강정아,김정희,김윤철,성보영,최성준,성인환,전은석 충남대학교 의과대학 지역사회의학연구소 2000 충남의대잡지 Vol.27 No.2

Platelet aggregation is the final pathway of acute coronary syndrome such as acute myocardial infarction and unstable angina. Platelet glycoprotein IIb/IIIa is a membrane receptor for fibrinogen and yon Willebrand factor and it plays an important role in platelet aggregation and in the pathogenesis of acute coronary syndrome. It is known that polymorphism of the gene that encoding platelet glycoprotein IIb/IIIa(PI^A1/A2) is strongly related to acute coronary syndrome in Caucasian, but not in Koreans. We investigated relationship between platelet glycoprotein llb/Illa gene polymorphism and restenosis of coronary artery after angioplasty in Koreans. Total 371 patients(M=251. F=120) were enrolled. Angioplasty group comprised 143 patients who underwent coronary angioplasty, and in the angioplasty group, restenosis group comprised with the 65 patients who had restenotic lesion over 50% of luminal diameter in follow-up coronary angiography. Normal group comprised 153 patients who had no significant angiographic lesion and variant angina group comprised 75 patients who were positive in ergonovine test. Genomic DNA was extracted from peripheral arterial blood. To determine the frequency of P1^A1/A2 genotype, polymerase chain reaction(PCR) was done and the product was restricted with Mspl. 3%. agarrose gel electrophoresis showed restriction fragment length polymorphism. Clinical profile and risk factor were also reviewed. Among all 371 patients of study group, genotype of only one patients in restenosis group if is proven to be PI^A1/A2 heterozygote. All patients of normal study group, no restenosis group, and the other patients in restenosis group have an PI^A1 homozygote genotype. In our study, platelet glycoprotein IIb/Illa polymorphism has no relationship with restenosis of the coronary artery after angioplasty in Koreans. But the genotypic frequency of platelet glycoprotein IIb/IIIa gene polymorphism in Koreans is concordant with that of previous studies.

Ring-on-ring 강도시험법을 이용한 200mm 반도체 실리콘 웨이퍼의 파괴강도 분석

정성민,박성은,오한석,이홍림 연세대학교 산업기술연구소 2000 논문집 Vol.32 No.2

Biaxial fracture strength of the commercial 200mm Czochralski single crystal silicon wafer was measured by the ring-on-ring technique and was compared with theoretical strength of Si single crystal. The ring-on-ring apparatus was newly designed and manufactured after analyzing stress distribution in ring-on-ring test with FEM(Finite Element Method) computerized simulation. Weibull modulus of the silicon wafer was also calculated from the measured fracture strength.

개에 있어서 심장사상충증을 동반한 창상성 횡격막 허니아의 수술적 치료 1례

조승혁,임영환,손정민,노경완,박창식,전무형,김명철,송근호,정성목 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

A 7-month old. castrated male Shih-tzu dog was referred to the Veterinary Medical Teaching Hospital of Chungnam National University with history of depression. dyspnea. mild scale. tachypnea. exercise intolerance and severe leanness. On physical examination. cardiac arrhythmias was heard and heart worm ELISA test was positive. Microfilaria was found on the direct blood smear. Survey radiographs showed loss of diaphragmatic line and cardiac silhouette. displacement of lung fields and presence of gas filled intestines in the thoracic cavity. Rib fracture and pelvic fracture with callus formation were found incidentally. On the basis of physical examination and radiographic findings. it was diagnosed as traumatic diaphragmatic hernia and heart worm disease. Herniorrhaphy was performed. Postoperatively. it was treated for heart worm disease and scale. There is no evidence of recurrence of diaphragmatic hernia and heart worm disease over 1 year.

이개 재건술 후 늑연골 공여부의 분석

백승준,임재호,백룡민,오갑성,백세민 大韓成形外科學會 1997 Archives of Plastic Surgery Vol.24 No.5

The harvesting of costal cartilage for the total ear reconstruction elicits various functional and aesthetic problems such as pneumothorax, atelectasis, pain, scar and chest contour deformities. Although the costal cartilage has been the most popular autogenous tissue for the total ear reconstruction, the studies about problems of donor site after harvesting the costal cartilage were relatively rare. From March 1989 to October 1996, 153 cases of total ear reconstruction by the costal cartilage framework insertion were done in our hospital and 61 cases whose follow up were done over 6 months were analysed for donor site scar, contour deformity and rate of satisfaction. The optimal age of microtia reconstruction was considered as over the age of 8, because of the growth of the ear and the volume of costal cartilage. Through a small incision, 3 ~ 4 cm, on the contralateral chest, the 6th, 7th and 8th costal cartilage were harvested with the outer layer of perichondrium for survival of the costal cartilage framework, the inner layer of perichondrium was remained for the growth of costal cartilage. There were 4 cases of uneventful pleural perforation, and remained no problems on the patients. The state of chest donor site were analyzed on 61 patients by use of medical records, medical photos and interview with the patients. Mean length and width of chest scar were 5.2 cm and 2.3 mm 79% of patients classified as excellent or acceptable. Chest contour deformity was observed on 39% and 85% of patients were satisfied with the result of donor site.