PZT 기반의 PZN-PNN-PZT 압전 소자의 다양한 조건에 따른 압전 특성 변화

최정식,이창현,신효순,여동훈,이준형,Choi, Jeoung Sik,Lee, Chang Hyun,Shin, Hyo Soon,Yeo, Dong Hun,Lee, Joon Hyung 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.11

$Pb(Zr,\;Ti)O_3$ (PZT) is a piezoelectric material applied in a typical actuator and has been actively studied. However, in order to overcome the limitations of PZT, piezoelectric ceramics comprising mixed solid solutions of PZT with various relaxer electric materials have been studied. The $Pb(Zn_{1/3}Nb_{2/3})-Pb(Ni_{1/3}Nb_{2/3})-Pb(Zr,\;Ti)O_3$ (PZN-PNN-PZT) piezoelectric ceramic, known to have high piezoelectric constant and electromechanical coupling coefficient, was studied herein. The piezoelectric characteristics with various Zr contents (Zr/Ti ratios), PZN molar ratios, and sintering temperatures were compared. The piezoelectric properties of $d_{33}=580pC/N$ and $k_P=0.68$ were obtained with the $0.1PZN-0.2PNN-0.7PbZr_{0.46}Ti_{0.54}O_3$ composition sintered at $1,290^{\circ}C$.

균질기에 의해 혼합된 물-벙커유의 배기가스 배출 특성에 관한 연구

최정식,한상구,최재혁,박상균,박노성,김대헌,Choi, Jung-Sik,Han, Sang-Goo,Choi, Jae-Hyuk,Park, Sang-Kyun,Park, Ro-Seong,Kim, Dae-Hun 해양환경안전학회 2013 海洋環境安全學會誌 Vol.19 No.5

In this study, we conducted a study on characteristics of exhaust gas emissions from boiler when water-bunker oil mixed by homogenizer was burned in boiler. The results showed that NOx concentration and CO concentration of the homogenized bunker oil was decreased by 19% and 54% compared to pure bunker oil pretreatment was not being performed. And, in the case of water-bunker A oil, the NOx concentration was decreased with increasing water mixing ratio in bunker A oil. In particular, the NOx concentration in exhaust gas of 20 %water-80 %bunker A oil decrease by 45 % compared with pure bunker-A. However, the CO concentration in exhaust gas of 20 %water-80 %bunker A oil shows irregular changes. This means that the mixing of water more than a certain amount can cause a decrease in combustion performance. From this result, it can be found that critical mixing ratio of water in bunker A oil for normal combustion is 15% in this study. Deposition amount of soot that is collected in the vicinity of the chimney was decreased with increasing water mixing ratio. 본 연구에서는 균질기에 의해 혼합된 물과 벙커-A를 보일러로 연소하였을 때의 배기 배출물 특성에 대해 연구를 수행하였다. 그 결과로 균질기로 균질화 된 벙커-A의 경우, 순수 벙커-A에 비해 NOx 농도는 19 %, CO 농도는 54 % 감소를 나타냈다. 물-벙커A의 경우 물 혼합 비율이 증가할수록 NOx 농도분포가 낮아지는 것을 확인할 수 있었다. 특히, 20 %물-80 %벙커-A의 경우 순수한 벙커-A 보다 배기가스 내 NOx 농도가 45 %까지 감소하였다. 그러나 20 %물-80 %벙커-A의 경우, CO농도 분포는 불규칙한 변화를 나타냈다. 이것은 일정량 이상의 물 혼합은 보일러의 연소 성능 저하 원인이 될 수 있다는 것을 의미한다. 이 결과로부터 본 연구에서 보일러의 정상 연소를 위한벙커A유 내 물의 한계 혼합율은 15 % 인 것을 알 수 있었다. 연돌 부근에서 채취한 매연 부착양은 물의 혼합율이 증가할수록 감소하였다.

한양방 병용요법으로 호전을 보인 막성 신증 환자 1례

최정식,윤성식,김진미,조충식,김철중,Choi, Jeong-Sik,Yoon, Seong-Sik,Kim, Jin-Mi,Cho, Chung-Sik,Kim, Cheol-Jung 대한한방내과학회 2009 大韓韓方內科學會誌 Vol.30 No.3

The patient was hospitalized for treatment of cerebral infarction (Lt. BG). He was a 61-year-old man who was diagnosed with membranous nephropathy (MN) in 2000. Before admission, he was admitted for treatment for cerebral infarction at another hospital. During that admission, his MN symptoms went from bad to worse, and medication for MN was started (steroid and cyclophosphamide therapy). In our hospital, we started herbal medicine and western medicine combination therapy as well as oriental rehabilitation therapy. Our main herbal medicine was Magsungsinyeom-bang(Moxingshenyanfang). After 5 months, levels of 24 hrs proteinuria, total cholesterol, LDL-cholesterol and triglyceride decreased, levels of serum albumin, total protein increased, and clinical symptoms (lower limb edema, general body weakness) improved.

Effect of Ultrasonic Irradiation on On-board Fuel Analyzed Using Gas Chromatography/Mass Spectrometry

최정식,Choi, Jung-Sik The Korean Society of Marine Environment and safet 2021 해양환경안전학회지 Vol.27 No.6

최근 선박용 연료유에 대한 황 함유량 규제를 준수하기 위해 저유황유의 수요가 증가하고 있다. 그러나 저유황유를 공급하는 시기, 지역, 회사 별로 그 품질이 상이함에 따라 선내 연료유 저장탱크에서는 과도한 슬러지가 발생하는 등 혼합 안정성에 대한 문제가 제기되고 있다. 따라서 본 연구는 초음파의 캐비테이션 현상을 이용하여 저유황유의 품질 향상을 하고자 하였다. 선내 저장 탱크에서 이종의 연료유가 혼합되는 상황을 모사하기 위해 두 가지 종류의 저유황유(황 함유량 0.5 % 이하 MGO, MDO)를 혼합하여 시료유로 사용하였다. 원료유와 50 wt.% 씩 혼합한 시료유를 120분 동안 초음파 처리하였으며, 40분 주기로 채취된 샘플은 GC/MS 분석을 수행하여 초음파 조사 시간에 따른 시료유의 조성 변화를 분석하였다. 연구결과, 초음파의 캐비테이션 효과로 인하여 화학결합이 깨지면서 MGO 내 존재하는 고분자량 화합물의 감소와 저분자량의 화합물 증가가 관찰되었다. MDO와 혼합유의 경우, 초음파 조사 후 저분자 화합물에 대한 상대 존재비의 부분적 증가가 관찰되었지만 시간과 상대 존재비 사이의 상관관계는 관찰되지 않았다. Since the enforcement of strict regulations on marine fuel oil sulfur content, demand for Low Sulfur Fuel Oil (LSFO) has been increasing. However, as LSFO properties vary greatly depending on the supply timing, region, and supplier, LSFOs can experience problems with sludge formation, blending compatibility, and stability once mixed into storage tanks. This study investigates using ultrasound cavitation effects to improve the quality of LSFOs in storage tanks. For marine gas oil (MGO), the results showed that the relative ratio of high molecular weight compounds to those of low molecular weight decreased after ultrasonic irradiation, due to cavitation-induced cracking of chemical bonds. For marine diesel oil (MDO) and blended oil, a small increase in the relative abundance of low weight molecular compounds was observed after treatment. However, no correlation between time and relative abundance was observed.

소평탕(消平湯)이 Streptozotocin으로 유발된 당뇨쥐의 혈당 및 항산화 효소 활성에 미치는 영향

최정식,장선규,조충식,김철중,한동운,Choi, Jeong-Sik,Chang, Sun-Kyu,Cho, Chung-Sik,Kim, Cheol-Jung,Han, Dong-Un 대한한방내과학회 2008 大韓韓方內科學會誌 Vol.29 No.1

Objective : This study wascarried out to understand the effect of Sopyung-tang (SPT) on blood glucose & antioxidant enzyme activities in streptozotocin-induced diabetic rats. Methods : SD rats were separated into three groups, each with 20 rats. Except the normal group, the other two groups were intra-peritoneally injected with streptozotocin 6mg/kg. The experimental group was treated with SPT extract 500mgkg/day for 4 weeks. The normal and control groups were treated with saline 500mg/kg/day for 4 weeks. Changes of plasma glucose level and body weight were observed. After4 weeks, liver and kidney weight, antioxidant enzyme activities, and survival rate were observed with histological changes on liver, kidney and pancreas. Results : In the experimental group, body weight and survival rate increased, while plasma glucose level decreased significantly. Liver and kidney weight, XOD activity decreased in the experimental group compared to the control. GSH-px and CAT activities andinsulin-immunoreactive granules in ${\beta}-cells$ increased significantly in the experimental group compared to the control. Conclusions : This study shows that SPT might be effective for treatment of diabetes and its complications, as well as reduction of oxidative stress.

Purification and Characterization of Antibacterial Peptides, Spodopsin Ia and Ib Induced in the Larval Haemolymph of the Common Cutworm, Spodoptera Iitura

최정식,여성문,김웅석,채권석,Choi, Chung-Sik,Yoe, Sung-Moon,Kim, Eung-Seok,Chae, Kwon-Seok,Kim, Hak R. The Korean Society for Integrative Biology 1997 Korean journal of biological sciences Vol.1 No.3

Antibacterial activity was induced in the haemolymph of the common cutworm, Spodoptera litura by the artificial injection of E, coli Ek132. Antibacterial peptides were purified from the immunized haemolymph by heat treatment, ion-exchange chromatography, gel filtration chromatography, and reverse phase FPLC, and their physicochemical characteristics were investigated. These purified antibacterial peptides designated as spodopsin la and Ib were named after Spodoptera litura. Spodopsin la and Ib had the apparent molecular masses of 3, 823 Da and 3, 886 Da, respectively, and about 20% of the sequences had basic amino acids, such as lysine and arginine but no cysteine. Also, spodopsin l was confirmed to be a new member of cecropin family having a similar amino acid sequence to cecropin of lepidopteran insects, such as Bombyx mori and Hyalophora cecropia. The purified spodopsin was active against gram-positive as well as gram-negative bacteria.

실습선 한바다호 주기관 배기가스 배출물질 특성 고찰에 관한 연구

최정식,이상득,김성윤,이경우,천강우,남연우,정균식,박상균,최재혁,Choi, Jung-Sik,Lee, Sang-Deuk,Kim, Seong-Yun,Lee, Kyoung-Woo,Chun, Kang-Woo,Nam, Youn-Woo,Jung, Kyun-Sik,Park, Sang-Kyun,Choi, Jae-Hyuk 해양환경안전학회 2013 해양환경안전학회지 Vol.19 No.6

In this study, we measured particulate matter(PM) which emerged as the hot issue from the International Maritime Organization(IMO) and the exhaust emission using HANBADA, the training ship of Korea Maritime University. In particular, the PM was obtained with TEM grid. PM structure was observed by electron microscopy. And exhaust gases such as NOx, $CO_2$, and CO were measured using the combustion gas analyzer(PG-250A, HORIBA). The results of this study are as follows. 1) When the ship departed from the port, the maximum difference in PM emissions were up to 30 % due to the Bunker Change. 2) Under the steady navigation, emission of PM was $1.34mg/m^3$ when Bunker-A is changing L.R.F.O(3 %). And, at the fixed L.R.F.O (3 %), emission of PM was $1.19mg/m^3$. When the main engine RPM increased up to 20 % with fixed L.R.F.O(3 %), emission of PM was $1.40mg/m^3$. When we changed to low quality oil(L.R.F.O(3 %)), CO concentration from main engine increased about 16 %. On the other hand, when the main engine RPM is rising up to 20 %, CO concentration is increased more than 152 percent. These results imply that the changes of RPM is a dominant factor in exhaust emission although fuel oil type is an important factor. 3) The diameter of PM obtained with TEM grid is about $4{\sim}10{\mu}m$ and its structure shows porous aggregate. 본 연구에서는 국제해사기구(IMO)의 뜨거운 관심분야로 부상되고 있는 선박기인 입자상물질(PM)과 오염물질 배출에 관하여 한국해양대학교 실습선 한바다호를 이용하여 계측하였다. 특히, PM은 TEM 그리드를 이용해 채취하고 전자현미경으로 구조를 파악하였으며, NOx, $CO_2$, CO 등의 배기가스는 연소가스분석기(PG-250A, HORIBA)를 이용해 측정하였다. 본 연구의 결과는 다음과 같다. 1) 선박이 항구에서 출항할 때, Bunker Change로 인한 PM 배출량은 최대 30 % 정도 차이가 있었다. 2) 정속 운항을 하면서 Bunker-A에서 L.R.F.O(3 %)로 변경할 때 측정한 PM 배출량은 $1.34mg/m^3$, L.R.F.O(3 %)로 고정해 측정한 PM 배출량은 $1.19mg/m^3$, L.R.F.O(3 %)만 사용하며 주기관 회전수를 20 % 증가시키면서 계측한 PM 배출량은 $1.40mg/m^3$ 이었다. 또한, 저질유(L.R.F.O(3 %))로 변경시 CO 농도는 약 16 % 증가하는데 비해 RPM을 20 % 상승시킨 경우에는 152 % 이상 급격한 증가를 보였다. 이러한 결과로부터 배기가스 배출의 증가는 연료유종의 영향도 있으나, RPM의 변화에 민감하다는 것을 알 수 있었다. 3) TEM 그리드로 채취한 PM은 약 $4{\sim}10{\mu}m$ 정도의 다양한 입경을 가지는 다공질 응집체 형상의 구조인 것으로 확인하였다.

실습선을 이용한 주 추진기관의 배기배출물의 실시간 계측

최정식,이상득,이경우,천강우,남연우,윤석훈,최재혁,Choi, Jung-Sik,Lee, Sang-Deuk,Lee, Kyoung-Woo,Chun, Kang-Woo,Nam, Youn-Woo,Yoon, Seok-Hun,Choi, Jae-Hyuk 해양환경안전학회 2013 海洋環境安全學會誌 Vol.19 No.5

본 연구에서는 한국해양대학교 실습선 한바다를 이용하여 선박의 입 출항 및 약 150 rpm의 정속 운항 할 때 주기관에서 배출되는 배기가스를 실시간 계측하였다. 실측 결과 질소산화물의 농도는 정속 운항시 800 ppm 에서 1,000 ppm 사이인데 반해, 입 출항시에는 210 ppm 에서 1,230 ppm 까지 큰 범위에서 값이 변화하였다. 일산화탄소의 농도 역시 정속운항 상태 보다 입 출항시 측정값의 변화가 크게 나타났다. 이러한 결과는 입 출항시 가능한 한 주기관의 부하변동이 급격히 발생되지 않도록 하는 선박 조종 스킬이 필요하다는 것을 의미한다. 또한, 배기가스 저감 기술의 적용에 있어 입 출항시와 정속 운항할 때 그 차이를 고려할 필요가 있다는 것을 나타낸다. In this study, we conducted real-time measurement at the ship arrivals and departures at the port and at a constant speed of 150 rpm for exhaust emissions from a main engine installed on the training ship, HANBADA, of Korea Maritime University. The result showed that the concentration of nitrogen oxide was measured in the range of 800 ppm to 1,000 ppm at constant speed mode. On the other hand, the concentration of nitrogen oxide during ship arrivals and departures was significantly fluctuated between 210 ppm and 1,230 ppm. And, the concentration of carbon oxide at the arrivals and departures was also larger than that of at constant speed mode. These results show that the ship maneuvering skills to prevent a sudden load change of main engine at the arrivals and departures of ship is needed. Additionally, it means that the difference of exhaust emissions generated between the constant speed mode and the arrival/departure has to be considered when invented many technologies are adopted into the reduction technologies of air pollutants from ships.

유색칼라 생육 및 구근 비대에 미치는 비가림 재배와 구근 크기의 효과

Choi So Ra(최소라),Hoi Chun Lim(임회춘),Dong Chil Choi(최동칠),Joung Sik Choi(최정식),Jung Ryu(류정),Yeong Geun Choi(최영근),Jong Sun Eun(은종선) (사)한국생물환경조절학회 2002 생물환경조절학회지 Vol.11 No.4

유색칼라 생육 구근 비대에 미치는 비가림 재배와 구근 크기의 효과

최소라(Choi S.R.),임회춘(Lim H.C.),최동칠(Choi D.C.),최정식(Choi J.S.),최영근(Choi Y.G.),은종선(Eun J.S.) 한국생물환경조절학회 2002 한국생물환경조절학회 학술발표논문집 Vol.- No.-