A-자리 결함 perovskite La_1/3NbO₃ 단결정의 유전특성

손정호,Sohn, Jeong-Ho 한국결정성장학회 2010 韓國結晶成長學會誌 Vol.20 No.6

After the specimen of A-site defect perovskite $La_{1/3}NbO_3$ single crystal was manufactured, the dielectric properties were studied between the temperature range of 10 and 800 K. The dielectric anomaly appeared at 50 K and 650 K, and, at about 650 K, the thermal hysteresis of dielectric constant was shown. The ac-conductivity of bulk showed the lowest activation energy of 0.43 eV at 560~690 K. Based on the results, it is assumed that the dielectric anomaly at 50K and 650 K was due to the antiparallel shift of $Nb^{5+}$-ion and the rearrangement of $Nb^{3+}$-ion, respectively. A-자리 경함 perovskite $La_{1/3}NbO_3$ 단결정 시편을 제작하여 10~800 K 온도범위에서 유전특성을 조사하였다. 50 K와 650 K 부근에서 유전이상이 나타났으며, 고온영역(약 650 K)에서 유전상수의 thermal hysterisis가 크게 나타났다. 교류전도도 측정으로부터 560~690 K에서 입내 활성화 에너지는 0.43 eV로 가장 낮게 나타났다. 이들의 결과로부터 50 K 부근의 dielectric anomaly는 $Nb^{5+}$-이온의 antiparallel 변위에 기인한 것이며, 650 K 부근의 dielectric anomaly는 $La^{3+}$-이온의 재배열에 기인한 것으로 추측된다.

폐국균종의 임상적 고찰

손정호 ( Jeong Ho Sohn ),강태경 ( Tae Kyung Kang ),김창호 ( Chang Ho Kim ),박재용 ( Jae Yong Park ),정태훈 ( Tae Hoon Jung ),이준호 ( Jun Ho Lee ),한승범 ( Seong Beom Han ),전영준 ( Young Jun Jeon ),김기범 ( Ki Beom Kim ),정진홍 ( 대한결핵 및 호흡기학회 1997 Tuberculosis and Respiratory Diseases Vol.44 No.6

혐기-호기공정과 오존을 이용한 염색폐수 및 슬러지 처리에 관한연구

손정호 ( Jeong Ho Sohn ),강용태 ( Yong Tae Kang ),송근관 ( Kune Kwan Song ),한상윤 ( Sang Yun Han ) 한국물환경학회 2009 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2009 No.-

농흉에서 전산화 단층촬영의 의의

허정숙 ( Jeong Suk Heo ),권오영 ( Oh Yong Kwun ),손정호 ( Jeong Ho Sohn ),최원일 ( Won Il Choi ),황재석 ( Jae Seok Hwang ),한승범 ( Seung Beom Han ),전영준 ( Young June Jean ),김정식 ( Jung Sik Kim ) 대한결핵 및 호흡기학회 1994 Tuberculosis and Respiratory Diseases Vol.41 No.4

학문목적 학습자를 대상으로 한 확장형 읽기 교육의 효과

배정선 ( Jeong Sun Bae ),손정호 ( Jeong Ho Sohn ) 연세대학교 언어연구교육원 한국어학당 2014 외국어로서의 한국어교육 Vol.41 No.-

As there has been a growing number of learners with academic purposes among Korean learners, there has been a lot of learners with difficulties in understanding the lessons of their majoring subjects accordingly. The cause of the difficulties is their familiarity with intensive reading in Korean reading class. Intensive reading requires accurate reading and understanding of a relatively short text is a good way to develop accuracy in reading. However it is not appropriate for reading a lot of reading materials concerning with their major and grasp the main points. therefore it is necessary 2 practicing extensive reading to read and understand the materials in Korean rapidly. Even though it has not been long that the extensive reading which has been widely used English education starts to be applied to Korean education, it is clear that extensive reading is helpful in Korean education as well. Thus, this study aims at finding out an appropriate way for Korean classroom through an experiment for a while and represents the effect. The experiment was done for 15 weeks with 31 learners and in class the practice and presentation on extensive reading and after class the learners chose a piece of reading material freely and write a log on a weekly basis. The researcher of this study explained the way and purpose of extensive reading throughly and let the learners practice without any help with a dictionary. Prior test to the experiment, the 8th week’s mid test and post test of the experiment were done to find out the improvement of the learners’ reading proficiency. A meaningful result came out from the T-test on both the prior test and post test. Especially the effect of education on the low performing learners was big and the effect on general understanding which is the main target of extensive reading was meaningful enough. With the result extensive reading is effective on improving reading ability for the low performing learners rather than the high performing learners, and proves that it is effective on general understanding rather than understanding minor things in detail. In addition, the survey represents that the emotional attitude toward extensive reading is very positive as well. This study proposes extensive reading as a way to improve reading ability of the Korean learners in the hope of active researches on the methods to apply the extensive reading to the Korean classroom in the future.

PLZT 경사 기능 재료를 이용한 세라믹 엑튜에이터

최승철,김한수,손정호,김현재,정형진,Choi, Seung-Chul,Kim, Han-Soo,Sohn, Jeong-Ho,Kim, Hyun-Jai,Jeong, Hyeong-Jin 한국재료학회 1991 한국재료학회지 Vol.1 No.2

압전 actuator를 위한 새로운 형태의 재료를 개발하여, 그 특성들을 조사하였다. 이 압전 actuator는 세 층으로 구성되어 있다: 압전 세라믹 층, 조성이 점차로 변하는 중간층, 그리고 또 다른 압전 세라믹 층, 이러한 형태이 재료는 경사 기능 재료(Functionally Gradient Material, FGM)라 불리운다. 경사 기능 재료를 제작하기 위한 재료설계의 개념을 도입하여, FGM화에 있어서 열팽창에 의한 시편의 박리를 막기 위해 $(Pb,\;La)(Zr,\;Ti)O_3$계에서 서로 다른 세라믹스의 조성을 선택하였다. $1300^{\circ}C$, 2시간의 소성에 의해 경사 기능화된 PLZT는 약 $20\mu\textrm{m}$정도의 중간층을 형성하는 미세구조를 가지고 있었다. 경사 기능 재료에서의 유전 및 압전 등의 여러 특성은 두 접합 조성층 특성의 사이의 값을 나타내었다. 인가 전압에 따른 strain특성은 전반적으로 단일 시편의 특성보다 증가하였으며, 특히 접합 조성층에서 고압전-저유전성 조성과 저압전-고유전성 조성을 경사 기능화하였을 경우에 변위의 증가 정도가 더욱 향상되었다. In PLZT system, a new type of material for piezoelectric actuator was developed and its properties were investigated. This material consists of three layers : a piezoelectric ceramic layer, an interlayer which composition changes gradually, and another piezoelectric layer. This kind of materials is called functionally Gradient Materials(FGM). The composition of these layers were selected from the $(Pb,\;La)(Zr,\;TiO_3$ system through the concept of materials design. Sintered FGM at $1300^{\circ}C$, 2hr has an interlayer of about $20\mu\textrm{m}$ with no distorted damage. Dielectric and piezoelectic properties of FGM show intervalues of each side composition. The strain-voltage characteristics in FGM system was improved comparison with any single composition. Especially, the FGMs were fabricated which has high piezoelectric-low dielectric composition and low piezoelectric-high dielectric composition. The properties of both FGMs were significantly improved.

수열합성공정에 의한 Zr_xCe_1-xO₂ 촉매 분말의 제조 및 특성

최연빈,손정훈,손정호,배동식,Choi, Yeon-Bin,Son, Jeong-hun,Sohn, Jeong Ho,Bae, Dong-Sik 한국결정성장학회 2017 한국결정성장학회지 Vol.27 No.6

세리아 분말은 Ce 이온의 산화, 환원 반응을 통한 산소저장능력(OSC)이 뛰어나 배기가스를 정화하는 자동차의 삼원촉매에 대표적인 재료로 사용된다. 그러나 일반적으로 세리아는 고온에서 열적 안정성이 떨어지기 때문에 금속이온을 도핑시켜 열적 안정성을 향상시켜 사용한다. 따라서 본 연구에서는 Zr 이온을 세리아 분말에 도핑시켰고, 도핑으로 인해 입자크기가 감소하면서 비 표면적 증가로 인해 그 특성은 더욱 향상되었다. 그리고 본 연구에서는 세리아 및 Zr 이온이 도핑된 세리아를 나노 크기로 합성하기 위해 수열반응법을 이용하여 합성하였다. 수열합성 조건은 pH = 11, 반응온도는 $200^{\circ}C$에서 6시간 동안 합성하였다. 수열합성법을 이용하여 합성된 세리아 및 Zr 도핑 $CeO_2$ 나노 분말의 평균 입자 크기는 약 20 nm 이하였다. 합성된 세리아 나노분말의 비표면적은 $52.03m^2/g$, Zr 이온이 도핑된 $CeO_2$ 분말의 비 표면적 $132.27m^2/g$이었다. The ceria powder is excellent in oxygen storage capacity (OSC) through the oxidation and reduction reaction of Ce ions and is used as a typical material for a three-way catalyst of an automobile which purifies the exhaust gas. However, since ceria generally has poor thermal stability at high temperatures, it is doped with metal ions to improve thermal stability. Therefore, in this study, Zr ions were doped into ceria powder, and their characteristics were further improved due to the increase of specific surface area with decreasing particle size due to doping. In this study, the synthesis of zirconium doped ceria nanopowder was synthesized by hydrothermal process. In order to synthesis Zr ion doped ceria nanopowder, the precursor reaction at was $200^{\circ}C$ for 6 hours. The average particle size of synthesized Zr doped $CeO_2$ nanopowder was below 20 nm. The specific surface area of synthesized Zr ion doped ceria nanopowder increased from $52.03m^2/g$ to $132.27m^2/g$ with Zr increased 30 %.

n=3인 Ruddlesden-Popper형 La_2.1Sr_1.9Mn₃O₁₀ 세라믹스의 Small polaron Hopping 전도 (II)

정우환,이준형,손정호,Jung, Woo-Hwan,Lee, Joon-Hyung,Sohn, Jeong-Ho 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.9

Mn계 층상 perovskite 세라믹스 $La_{2.1}Sr_{1.9}Mn_3O_{10}$의 전기저항 및 열기전력의 온도의존성을 측정하였다. 실험결과 $La_{2.1}Sr_{1.9}Mn_3O_{10}$의 전기전도는 Emin-Holstein의 단열 small polaron model에 의하여 이루어지고 있었다. Curie 온도이상의 small polaron hopping 영역에서의 열기전력 측정결과는 이론적인 $Mn^{4+}$ 가전자 관점에서 예측되었던 열기전력 측정 결과와 거의 동일하였다. 이 실험결과 역시 $La_{2.1}Sr_{1.9}Mn_3O_{10}$ 세라믹스의 전기전도가 small polaron에 의하여 이루어지고 있음을 의미한다. Electrical resistivity and thermoelectric power measurements on Mn-based $La_{2.1}Sr_{1.9}Mn_3O_{10}$ with layered perovskite structure as functions of temperature are presented. The experimental results demonstrate that the electronic transport in $La_{2.1}Sr_{1.9}Mn_3O_{10}$ is well described by the Emin-Holstein adiabatic small polaron model. The thermoelectric power data in the small polaron regime above Curie temperature is nearly equal to that predicted by nominal $Mn^{4+}$ valence arguments. This indicates that transport involves small polaron hopping.

터널페수 처리를 위한 최적응집제 결정

강용태 ( Yong Tae Kang ),손정호 ( Jeong Ho Sohn ),김남경 ( Nam Kyoung Kim ),송근관 ( Keune Kwan Song ) 한국수처리학회 2012 한국수처리학회지 Vol.20 No.1

The objective of this study is to evaluate the optimum coagulant for efficient treatment of tunneling wastewater with high turbidity concentration of 790-827 NTU. The pH and dosage of coagulant were changed for determination of optimum coagulant for tunneling wastewater treatment. Characteristics of influent tunneling wastewater were: pH 6.94~7.05, Turbidity 790~827 NTU and SS 543~595 mg/L. Optimum coagulant was determined by jar-test using Alum. PSQ-M. PAC. PACS-II and FeCla as a coagulant. Based on the results of jar-test. optimum pH values were 9 for alum and PSO-M and 7 for PAC. PACS-II and FeCI3. respectively. Optimum dosages of coagulants were: alum 70 mg/L. PSO-M 10 mg/L. PAC 50 mg/L. PACS-II 10 mglL and FeCla 15 mglL. respectively. Operation costs of alum. PSO-M. PAC. PACS-II and FeCI3 were 127.6 won/kg. 118.9 won/kg. 15.5 won/kg, 3.3 won/kg and 3.6 won/kg. respectively. When considering optimum pH and dosage of coagulant. PACS-II coagulant was more effective than Alum, PSO-M, PAC and FeCl3.

터널폐수를 이용한 HCF와 DAQUA system의 처리효율 비교연구

강용태 ( Yong Tae Kang ),손정호 ( Jeong Ho Sohn ),김연은 ( Yun Eun Kim ),정세욱 ( Sae Wook Jeong ),이제현 ( Jae Hyun Lee ) 한국수처리학회 2012 한국수처리학회지 Vol.20 No.2

In this paper, DAQUA System is composed with coagulating sedimentation and gravity flow fiber filtration. And application of inclination tube makes more higher sedeimentation efficiency. Three kinds of tunneling wastewater is treated for turbidity and heavy metals on DAQUA System which compared with wastewater treatment system in the actual on the field The results were revealed that Case 1. Case 2 and Case 3 each made different coagulation sedimentation effluent turbidity 0.2~9.2NTU(average 6 .45NTU), 27.0~45.0 NTU(average 34.7NTU). 67.0~121.ONTU(average 81 .4NTU) respectively. And turbidity of fiber filter effluent were 0.70~4.57NTU(average 1 .64NTU), 4.9~7.4NTU(average 6.19NTU). 14.52~42.1 5NTU(average 20.35NTU) respectively. Also sludge drained from coagulating sedimentation basin with intervals of 25-30 minutes. Final effluent was stable even if High Turbidity of raw water is entered coagulating sedimentation basin, because sludge drained shortly. Al, Fe and Mn average effluent concentration of lmg/L or more was not outflow. Tunnel wastewater treatment system is excellent, because of effluent turbidity were low twice as high in DAQUA system than the traditional tunneling wastewater treatment system.