"Dice와 fill" 방식을 이용한 1-3 압전복합재의 제조와 횡방향 단위 크기에 따른 압전특성 평가

김영덕,김광일,정우철,김흥락,김동수 한국비파괴검사학회 2002 한국비파괴검사학회지 Vol.22 No.4

NDT나 의료용 영상장치에 응용되는 압전복합체는 일반적인 세라믹이나 고분자 압전재료에 비하여 많은 장점을 가진다. 이들 응용분야에서는 전기기계결합게수가 높아야 하고, 음향임피던스가 낮아야 한다. 그러나, 압전복합제의 횡방향 단위 크기가 조밀하지 못한 경우 횡방향으로 전행하는 판파에 의한 불필요한 진동이 표면에 발생하게 된다. 횡방향 단위 크기와 세라믹 체적비에 따른 압전 특성을 조사하기 위하여 PMN-PZT 세라믹과 Epofix 에폭시로 에폭시의 폭을 달리하면서 1-3 형 압전복합체를 제작하였다. 제작된 1-3형 압전복합체의 두께방향 진동모드의 전기기계결합계수, 음향임피던스는 각각 0.36~0.64, 9.8~22.7 MRayl로 나타났으며, 횡방향 단위크기가 줄어들수록 횡방향 모드 공진 주파수가 증가하였다. The piezoelectric composites had many adventages in comparison qith conventional piezoelectric ceramics and piezopolymers for ultrasonic transducers used in NDT and in medical ultrasonic imaging. The electromechanical coupling coeffucient should be high and the acoustic impedance should be low in these applications. However, the cross-coupling with spurious oscillations caused lateral spatial scale. The thickness mode electomechanical coupling coefficient of 1-3 type of piezoelectric composites were 0.36 to 0.64, and the acoustic impedance of them were 9.8 to 22.7 MRayl. The lateral resonance frequency of 1-3 type piezoelectric composites shifted to high frequency region with decreasing lateral spatial scale.

로케트 工學에 관한 硏究 : 第1報 : 亞音速 亂流流動에서 飛行翼模型의 剝離現象 Ⅰst Report : Separation of Airfoils in Subsonic Turbulent Flow

朴煥奎,金鍾一,金鎭興,李茂錫,朴吉文,鄭洛奎,李行男,李東起 조선대학교 동력자원연구소 1984 動力資源硏究所誌 Vol.6 No.2

Separation, pressure and velocity distributions were studied fully developed two dimensinonal, incompressible flow over a flat airfoil in subsonic wind tunnel. Velocity and turbulence were measured with a two channel constant temperature hot wire anemometer and pressure with a pitot tube and pressure tranducer system. The experimental results were obtained as follow: (1) Turbulent intensity of shear layer just outside the separation point is considered to affect the size of separation bubble. (2) Static pressure coefficient is separated into three regions according to its value change. (3) Separation point is varied with the change of attack angle. (4) Velocity distributions and boundary layers normal to airfoil surface are changed as variation of attack angle of airfoil.

방사광을 이용한 Si 웨이퍼 표면불순물 검출감도 향상

김흥락(Heung Rak Kim),김광일(Kwang Il Kim),강성건(Sung Gun Kang),김동수(Dong Soo Kim),윤화식(Hwa Shik Yoon),류근걸(Kun Kul Ryoo),김영주(Young Joo Kim) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.1

방사광을 이용한 전반사 형광 분석법으로 Si 웨이퍼 표면 금속 불순물의 검출능을 향상시켰다. 측정장치는 특정 단색광 에너지만을 선택할 수 있는 모노크로메팅부, 측정챔버안으로 유입되는 방사광은 차폐하고 원하는 크기의 단색광을 선택하는 슬릿부 그리고 Si 웨이퍼 표면에서 전반사에 의해 발생하는 형광 X-선을 검출하는 측정부로 구성되어 있다. 단색광의 에너지는 10.90 KeV로 선택하였고, 최적의 전반사 조건을 확립하기 위하여 소멸시간과 Fe의 형광 X-선의 강도비의 관계를 이용하였다. 기존 X-선원을 이용하여 관찰한 결과와 비교하였을 경우에, 최대 약 50배까지 검출감도를 향상 시킬 수 있었다. 특히, TRXFA (Total Reflection X-ray Fluorescence Analyzer)법으로는 검출하기 어려운 5×10^10 atoms/㎠ 수준의 금속오염은 방사광을 이용한 TRSFA(Total Reflection Synchrotron Fluorescence Analyzer)법으로는 충분히 검출할 수 있고, 5×10^9 atoms/㎠의 금속 불순물까지 검출할 수 있는 방법 및 장치를 개발하였다. 이를 이용하여 차세대 Si 웨이퍼의 초극미량 금속 불순물 분석에 이용할 수 있는 방법으로 기대된다. Total reflection X-ray fluorescence spectroscopy using synchrotron radiation source called as TRSFA was explored to achieve high sensitivities to impurity metals on Si wafer surface. It consists of monochromating part to select a specific wavelength, slit part to shield direct beam and to control monochromated beam, and main chamber to dectect fluorescent X-ray counts of impurities on Si wafer. Monochromated X-ray of 10.90 KeV was selected and the optimum total reflection condition on silicon wafer was obtained through tuning the dead time and fluorescent X-ray count of Si and Fe. TRSFA system could increase the sensitivity as high as 50 times in comparision with TRXFA using normal X-ray source. But the trend was varied since the surface conditions of Si wafers and, therefore, the reflectivities were different. Furthermore, there seems to be a promising path to reaching a detection limit useful to the next generation metal impurities control, because Fe impurity below to the 5×10^9 atoms/㎠ can be detectable through the developed TRSFA system.

개방형 우물 구조를 이용한 마이크로머신형 pH 센서

김흥락,김영덕,정우철,김광일,김동수 한국비파괴검사학회 2002 한국비파괴검사학회지 Vol.22 No.4

수용액에 포함된 수소이온(H^+)의 농도를 측정하는 유리 전극형 수소이온 농도(pH) 센서의 기본 구조를 bulk micromachining 기술로 구현하여 소형의 pH센서를 제작하였다. 박막 증착이 가능한 경사 식각으로 개방된 2개의 기본 구조물을 형성하고, 일정 전위를 유지하기위한 기준전극은 식각된 구조물 경사면에 박막형 Ag/Agcl으로 확보하였다. H^+과 교환반응으로 전위를 발생시키는 감응부는 Na 20%이상 포함된 glass로 100㎛ 내외로 미세 연마하여 기본 구조물에 접합하여 완성하였다. 또한 외부 용액과 기준 용액의 혼합을 방지하면서 전류 도통 역할을 하는 액간 접촉부는 50㎛ × 50㎛ 크기의 Si 이방성 식각 부분에 한천을 삽입하고 난 다음 기존의 구조물에 접합하여 형성하였다. 각 구조물을 완성한 다음 2M 농도의 KCl 기준 용액을 구조물에 채우고, 상온 에폭시로 센서 구조물을 밀봉하여 센서를 완성하였다. 제작된 pH센서들은 표준 pH 용액에 대하여 약 90mV/pH의 전위값이 측정되었다. A structure of a glass electrode-type pH sensor for measuring any concentration of H^+ in an aqueous solution was embodies with bulk micromachining technology. Two open well structure were formed, and a reference electrode was secured by the Ag/AgCl thin film in the sloped side of the etched structure. A sensitive membrane of an indicator electrode for generationg a potential by an exchange reaction to H^+ was made with a glass containing Na 20% or more finely so that its thickness might be 100㎛ or so, and then it was bonded to one pyramidal structure. A liquid junction for a current path was formed by filling an agar in the anisotropically etched part of the Si wafer, which had a size of 50㎛ × 50㎛, and then bonded it to the other. after complete fabrication of each part, it was filled qith a 2M KCl reference solution and encapsulated the sesor structure with a cold epoxy. The potential value of fabricated pH sensor was about 90mV/pH in the standard pH solutions.

Effects of Temperature on the Development of Tropidothorax cruciger(Hemiptera:Lygaeidae)on Cynanchum wilfordii

Kim, Tae-Heung,Kwak, Jun-Su,Lim, Ju-rak,Kim, Ju Korean Society of Applied Entomology 2001 Journal of Asia-Pacific Entomology Vol.4 No.1

Tropidothorax cruciger (Motschulsky) was reared on buds and leaves of Cynanchum wilfordii Hemsley at constant temperatures of 15, 18, 23, 28, and 33$\pm$1$^{\circ}C$ in the laboratory. Eggs of T. cruciger did not hatch at 15$^{\circ}C$. Egg periods were 21.9, 14.2, 8.5, and 7.8 days at 18, 23, 28, and 33$^{\circ}C$, respectively. Nymphal periods were 69.4, 52.6, 30.5, and 290.2 days, and egg to adult emergence periods were 91.3, 66.8, 39.0, and 28.0 days at 18, 23, 28, and 33$^{\circ}C$ for egg ad nymph stages, respectively. When the egg and nymphal stadia were polled, the DT temperature turned out to be 12.6$^{\circ}C$. Accumulated effective temperatures (ET) for stages of egg, nymph, and egg-nymph combined were 171.8, 420.7, and 589.9 day-degrees, respectively. Longevity of adults was 47.8, 54.4, 31.9, and 18.5 days and the number of eggs laid per female was 27.8, 34.0, 30.8, and 23.4 at the above temperatures, respectively. the rates of hatching were 35.6, 85.1, 68.1, and 39.4%, respectively at the temperatures previously given.

Dephosphorylation of Phytate from Rice Bran and Soybean Meal Using Phytases from Aspergillus sp. 5990

Kim, Jong Soon,Kim, Doo-Sang,Kim, Hyeng-Rak,Shin, Tai-Sun,Kim, Heung-Yoon,Oh, Myong-Joo,Byun, Dae-Seok 한국수산학회 2004 Fisheries and Aquatic Sciences Vol.7 No.2

Total phosphorus contents in rice bran and soybean meal were determined to be 5.81 and 2.77%, respectively, and 97.2% of phosphorus in rice bran and 66.4% in soybean meal were presented as phytate phosphorus. Optimum pH condition for hydrolysis of phytate in rice bran and soybean was determined to be in the pH range of 3.7 and 5.3. The highest activity of phytase for hydrolysis of phytate in both samples was determined to be at 55°C for rice bran and 55-60'C for soybean. Hydrolysis of phytate in soybean meal at pH 5.0 increased with the co-reaction or consecutive reaction with protease; however, in rice bran hydrolysis decreased with co-reaction with protease. Phytate degradation of soybean meal in the presence of pepsin at pH 2.5 showed higher than that of rice bran. Phytate degradation of rice bran in the presence of trypsin or pancreatin at pH 7.0 increased the activity around 2-times compared with the activity in the absence of trypsin or pancreatin. The results of this study suggest that hydrolysis of phytate in rice bran or soybean meal with phytase and protease may provide an alternative process for the preparation of aquacultural feed with a low level of organic phosphorus.

이산사건 형식론에 근거한 분산문제해결 프레임워크의 구현

김흥범(Heung Bum Kim),성영락(Young Rak Sung),김탁곤(Tag Gon Kim),박규호(Kyu Ho Park) 한국정보과학회 1997 정보과학회논문지(B) Vol.24 No.2

분산문제해결 시스템에서는 문제와 문제해결 환경에 대한 부분적인 자료와 지식만을 가진 여러 지능형 에이전트(intelligent agent)들이 하나의 팀을 이루어 서로 협력하면서 문제를 해결한다. 분산문제 해결 시스템은 일종의 이산사건 시스템이다. 문제해결 과정에서 지능형 에이전트는 외부 환경과 다른 지능형 에이전트들로 부터 불규칙적으로 메세지를 수신하고 처리한다. 본 논문에서는 이산사건 시스템을 규정하는 DEVS(Discrete Event Systems Specification)형식론에 기초한 분산문제해결 프레임워크를 제안한다. 제안된 프레임워크는 SOLVING-AGENT와 MANAGING-AGENT로 구성된다. SOLVING-AGENT는 문제해결 계획들을 가지고 있을 뿐만 아니라, 동시에 많은 문제를 해결할 수 있다. 그리고 MANAGING-AGENT는 SOLVING-AGENT들의 capability와 load factor를 가지고 있으며, 또한 문제해결 동안에는 메세지를 분배한다. 제안된 분산문제해결 프레임워크의 성능을 확인하기 위하여, 세개의 지능형 에이전트를 갖는 시스템에 대하여 실험하였다. 실험결과, 분산문제해결 프레임워크는 동시에 여러 개의 문제들을 해결하고, 각 SOLVING-AGENT에 일이 균등하게 분배됨을 보였다. Distributed Problem Solving(DPS) is an area of distributed artificial intelligence. In a DPS system, a problem is solved by a team of cooperating intelligent agents. Each intelligent agent has only partial data and knowledge of the problem and the problem solving environment. A DPS system is a discrete event system. During problem solving, an intelligent agent randomly receives and processes messages from outside and other intelligent agents; it also unpredictably activates knowledge sources in itself. This paper proposes a DPS framework based on the DEVS formalism. The formalism specifies discrete event systems in a hierarchical, modular manner. The framework consists of two components, SOLVING-AGENT and MANAGING-AGENT, SOLVING-AGENT maintains several problem-solving plans. It can solve many problems concurrently. MANAGING-AGENT keeps the capability and load factor of SOLVING-AGENTs. Also it distributes messages to SOLVING-AGENTs. For verifying the proposed framework, an example system with three intelligent agents was examined. It concurrently solves given problems. Also, computing loads are evenly distributed to each SOLVING-AGENT.

서울지역 길고양이의 Toxoplasma 감염증 실태조사

김능희 ( Neung Hee Kim ),채희선 ( Hee Sun Chae ),한혜진 ( Hye Jin Han ),손홍락 ( Hong Rak Son ),김창기 ( Chang Ki Kim ),김선흥 ( Sun Heung Kim ),이정학 ( Jung Hark Lee ),김철훈 ( Chul Hun Kim ) 한국가축위생학회 2009 韓國家畜衛生學會誌 Vol.32 No.3

Toxoplasma gondii is one of the most common protozoa parasites of human and other warm-blooded animals. Cats and wild felidae play crucial roles in the epidemiology of toxoplasmosis. This study was performed to survey the prevalence of T. gondii infection among stray cats in the Seoul. A total of 422 stray cat blood samples were collected from Seoul area. Positive sera for T. gondii were identified in 56 samples (13.3%) exclusively via the latex agglutination test and the detection no antigen particles among seropositive samples by PCR. The overall infection rate of male stray cats (14.4%) presented as higher than that of female cats (10.7%). This study suggested that T. gondii is widespread in stray cats of Seoul area. It is needed to control urban stray cat population and to reduced the risk of zoonotic transmission of toxolasmosis to other animals and humans.

서울지역의 개와 고양이에서 분리한 Staphylococcus aureus의 항생제 감수성 및 multiplex PCR을 이용한 장독소의 검출

김능희 ( Neung Hee Kim ),채희선 ( Hee Sun Chae ),손홍락 ( Hong Rak Son ),김창기 ( Chang Ki Kim ),김선흥 ( Sun Heung Kim ),이정학 ( Jung Hark Lee ),김철훈 ( Chul Hun Kim ) 한국가축위생학회 2010 韓國家畜衛生學會誌 Vol.33 No.3

The antimicrobial susceptibility of 73 strains of Staphylococcus aureus isolated from dogs and cats was determined against 16 antimicrobial agents. All isolates were susceptible to cephalothin (CF), vancomycin (VA), rifampin (RA), quinupristin-dalfopristin (SYN) and linezolid (LZD), whereas more than 86.3% of the isolates were resistant to penicillin (P). In the case of enterotoxin production, 8.2% of 73 strains produced enterotoxin A and 1 strain produced enterotoxin C. Appropriate protocols for antimicrobial agents and strategies to reduce antimicrobial resistance will need to be investigated in the future.

소의 분변과 도체에서 shiga toxin-producing Escherichia coli의 분리와 특성

채희선 ( Hee Sun Chae ),김능희 ( Neung Hee Kim ),한혜진 ( Hye Jin Han ),손홍락 ( Hong Rak Son ),김창기 ( Chang Ki Kim ),김선흥 ( Sun Heung Kim ),이정학 ( Jung Hark Lee ),김종택 ( Jong Taek Kim ) 한국가축위생학회 2009 韓國家畜衛生學會誌 Vol.32 No.3

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains can cause broad spectrum of human disease, including diarrhea, hemorrhagic colitis, and the life-threatening hemolytic uremic colitis (HUS). We examined 868 samples was taken from bovine feces and carcass from January to December 2008 in Seoul. Twenty two (9.5%) shiga toxin -producing Escherichia coli were isolated from the 230 of bovine feces, and two (0.31%) were isolated from the 638 of carcasses. Serotype of E. coli isolates were O157 (10, 41.6%), O26 (10, 41.6%), O111 (1, 4.2%) and UT (3, 12.6%). In PCR, the isolates displayed three different stx gene combination (stx1〔2, 8.4%〕], stx2〔3, 12.6%〕and stx1 and stx2〔19, 87.5%〕). The eaeA and hlyA gene were found in 11 (45.8%) of the 24 strains. Saa gene was present only one strains (4.2%). Toxin typing using reverse passive latex agglutination test showed the same result in VT 1. But it showed different result in VT 2. In antimicrobial susceptibility test, all isolates were sensitive to amikacin, amoxicillin/clavulanic acid, ciprofloxacin and colistin. Eighteen strains (75.0%) of 24 isolates showed the multi-resistant patterns with over 3 drugs. PFGE was performed after the genomic DNA of twenty four isolates was digested with Xba I. the 24 isolates showed 7 (A~G) PFGE type.