Impedance를 이용한 전도성고분자 센서의 가스감응특성

이경문,유준부,이병수,전희권,이상태,이덕동,허증수 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

휴대폰 카메라용 자동초점 구동기의 충격해석

이성민,김봉석,송준호,이수훈,이혜진,이문구,송준엽,이창우 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

Recently, the robustness against daily impact is important according to portablization and downsizing of mobile electronics. Especially, almost parts of cellular phone should undergo drop test when they fall 1.5 m above ground. This test simulates the case when cellular phone slips through user's fingers while he is talking on the phone. This paper studies a drop test of auto focusing (AF) actuator for camera module in cellular phone. This component is composed of voice coil motor (VCM) as an actuator and leaf spring as a guide and suspension. The leaf spring's deformation is essential for the test because its permanent distortion disables the focusing, and then, a high quality photograph cannot be obtained. Up to now the drop test has been carried out after fabricating real AF actuator. We propose a dropt test model which simulates the drop test based on finite element analysis. This model makes us enable investigate the stress acting on the clamping and curved parts of leaf spring. Stress over Von Mises criterion lets the spring deformed permanently, and then AF actuator malfunctioned, It helps us to design and modify AF actuator without manufacturing the real product. And also, it saves the time and cost for the development of new products.

전도성 고분자 센서 어레이를 이용한 휘발성 유기 화합물 가스 인식

이경문,주병수,유준부,황하룡,이병수,이덕동,변형기,허증수 한국센서학회 2002 센서학회지 Vol.11 No.5

휘발성 유기 화합물 가스(Volatile Organic Compounds)를 인식하고 분석하기 위하여 전도성 고분자 센서어레이를 이용한 시스템을 제작하였다. Polypyrrole와 Polyaniline을 화학중합법으로 센서에 전도성고분자막을 형성하였고 이를 통해 VOC 검지용 센서 어레이를 제작하였다. 센서어레이로부터 측정되는 다차원 데이터는 주성분분석법(PCA)과 RBF(Radial Basis Function Network)을 이용하였다. 제안된 시스템으로 VOCs 가스를 인식하는데 있어서 RBF Network이 PCA방식보다 더욱 효율적인 것으로 판단되었다. We fabricated gas recognition system using conducting polymer sensor array for recognizing and analyzing VOCs(Volatile Organic Compounds) gases. The polypyrrole and polyaniline thin film sensors which were made by chemical polymerization were employed to detect VOCs. The multi-dimensional sensor signals obtained from the sensor array were analyzed using PCA(principal component analysis) technique and RBF(radial basis function) Network. Throughout the experimental trails, we confirmed that RBF Network is effective than PCA technique in identifying VOCs.

Ti-6Al-4V 합금의 동적변형특성과 탄도충격성능 : 1. 초고속 폭발충격 특성 1. Ultra-high-speed Exploding Properties

이유환,이동근,이성학,이종수,최준홍,허선무 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.10

The effects of microstructural morphology on ultra-high-speed exploding properties of Ti-6Al-4V alloy were investigated in this study. Exploding bridge wire (EBW) test was conducted on equiaxed and bimodal microstructures, which were processed by different heat treatments. From the test, moving velocity of free surface vs time profiles were obtained to measure strength at Hugoniot elastic limit (HEL) and spall strength and to subsequently predict ballistic mass efficiency. The EBW results indicated that impact resistance of the bimodal microstructure was better than that of the equiaxed microstructure when the measured strength at HEL and spall strength were considered. It was also learned from the observation of fractured EBW specimens that fracture occurred by the initiation and propagation of long cracks in the equiaxed microstructure, whereas a number of microcracks were formed and connected each other in a zig-zag pattern to reduce the driving force for crack propagation in the bimodal microstructure. Since the EBW test helped experimentally estimate ultra-high-speed deformation and fracture behavior, it could be effectively used for the prediction of ballistic impact performance.

수근관 증후군에서의 무증상성 척골신경병증

문준식,이성수,이지용,한범기,권준범,양현덕,이성익 대한신경과학회 1999 대한신경과학회지 Vol.17 No.2

혼수상태의 외상환자에서 초음파를 이용한 흉부 및 복부손상의 진단

임경수,이강현,이진웅,이부수,황성오,유수영,강성준 대한응급의학회 1995 대한응급의학회지 Vol.6 No.1

The need for rapid diagnosis and treatment of life-threatening thoracic and intra-abdominal injury result in controversy over the appropriate triage of unconscious blunt trauma patients. To aid in early decisions for these patients, a prospective analysis of 98 patients with glasgow coma scale(GCS) scores≤8 was undertaken. Although intra-thoracic and intra-abdominal injuries were frequently identified based on systolic blood ressure, the use of clinical signs alone resulted in more missed injuries than did using the emergency ultrasonography. In normotensive patients(n=34), intra-thoracic injuries was identified in one patient(2.9%), and intra-abdominal injuries were in 7 patients(20.6%). In shock(systolic blood pressure<90mmHg) Pa-tients(n=64), thoracic injuries and intra-abdominal injuries were diagnosed in 8(12.5%) and 27 patients(42.3%), thoracic and abdominal combined injuries were identified in 11 patients(17.2%). The sensitivity, specificity, and accuracy of emergency ultrasonography were 96.3%, 91.7%, 94.9%. This study suggests that all unconscious trauma patients undergo immediate emergency ultrasonography to prevent missing life-threatening injuries.

소유-지배 괴리도가 경영진단의견서 공시에 미치는 영향

채수준(Chae, Soo-Joon),이아영(Lee, A-Young) 한국경영교육학회 2020 경영교육연구 Vol.35 No.4

[연구목적] 본 연구는 소유지배괴리도가 공시품질에 어떠한 영향을 미치는 지 분석하고자 하였다. 소유지배괴리도는 공정거래위원회가 ‘대규모기업집단 정보공개시스템’을 통해 제공하고 있는 지배주주의 소유권 및 지배권을 사용하여 측정하였으며, 공시품질로는 경영진단의견서(MD&A)를 고려하였다. [연구방법] 본 연구는 소유지배괴리도가 경영진단의견서 공시품질에 미치는 영향을 검증하기 위해서 2010년부터 2013년까지 유가증권시장에 상장된 1,483 기업-연도 표본을 대상으로 선형회귀분석을 실행하였다. [연구결과] 소유지배괴리도와 MD&A 공시품질 간에는 유의한 양(+)의 관련성이 존재하는 것으로 나타났다. 즉, 소유지배괴리도가 큰 기업일수록 MD&A 공시사항을 충실히 기재하고 있음을 확인하였다. 이는 상반된 두개의 해석을 가능하게 한다. 높은 소유지배괴리도로 인한 지배주주의 사익추구 가능성을 은폐하기 위한 수단으로 공시를 적극적으로 활용할 수 있다는 측면과 높은 소유지배괴리도로 인한 기업지배구조에 대한 부정적인 기업이미지를 해소하고 시장과 원활하게 소통하기 위해 공시를 활용할 수 있다는 해석이 가능하다. [연구의 시사점] 본 연구는 소유지배괴리도와 같은 기업의 소유구조가 기업의 공시품질에 영향을 미치는 요소임을 규명한다는 점에서 공헌도가 있다. 본 연구의 실증결과는 괴리도가 큰 기업일수록 MD&A와 같은 재량적 공시를 적극적으로 수행함으로써 소유구조에 따른 대리인 비용 및 정보비대칭을 완화하고자 하고 있음을 보여준다. 아울러, 대규모 기업집단 지정과 같은 규제제도가 기업들에게 스스로를 관리하게 하는 유인이 될 수 있음을 시사한다. [Purpose] The purpose of this study is to analyze how control-ownership wedge affects disclosure quality. We consider Management Discussion and Analysis(MD&A) as a proxy for disclosure quality [Methodology] This study conducted a linear regression analysis for 1,483 firm-year samples listed on the KOSPI market from the period between 2010 to 2013 to verify the effect of the ownership and control wedge on MD&A. [Findings] This paper showed that there is a significant positive (+) relationship between control-ownership wedge and MD&A disclosure quality. The results of this study verified that firms with a greater degree of control-ownership wedge faithfully described MD&A disclosure items. These results can be explained in two opposite directions. One explanation is that managers of firms with a greater degree of control-ownership wedge can actively use the MD&A disclosure as a mean to conceal the pursuit of the interests of the controlling shareholders. The other explanation is that the MD&A disclosure can be used to solve the negative corporate image of the corporate governance structure due to a high degree of control-ownership wedge and to communicate smoothly with the capital market. [Implications] This study has a contribution that the company’s ownership structure, such as the control-ownership wedge, is a factor influencing the disclosure quality of the company. The empirical results of this study show that firms with a greater degree of control-ownership wedge actively disclose the discretionary disclosure such as MD&A to alleviate agency cost and information asymmetries according to the ownership structure.

Al-Si 합금 열간단조품 내부의 판상 결함의 초음파 특성

이석원,전만수,이준현 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.6

본 연구에서는 Al-Si 합금 열간단조품 내부 판상 결함을 탐지하기 위한 초음파평가 기법을 확립하였다. 이를 위하여 내부에 존재하는 여러 가지 판상 결함의 초음파 특성을 실험적으로 구하였으며, 펄스-반사법을 적응하여 초음파 탐상신호에 대한 내부 판상 결함의 각도 등이 초음파 수신신호의 형태에 미치는 영향을 평가하였다. 한편 결함위치에 따른 초음파 신호특성을 규명하기 위하여 단조품 가장자리 부위에 존재하는 내부 판상 결함의 초음파 수신신호 특성을 평가하였으며, 본 시험편에 대한 초음파 투과법 적용 한계에 대하여 고찰하였다. 나아가 500개 이상의 파단 실험을 통해 제시된 초음파 평가기법의 신뢰성을 확인하였다. A nondestructive evaluation technique for detecting internal defects of an hot forged Al-Si allyoy part is established in this study. Ultrasonic characteristics of various internal planar defects are investigated by experiments for establishing a reliable test procedure. The effect of the angle between ultrasonic energy propagation directions and planar defects on the ultrasonic signal configuration is evaluated in the pulse-echo technique. A characteristic of ultrasonic signal for the internal planar defect located near the edge is also evaluated. The applicability of the through-transmission technique is also discussed. Reliability of the presented approach is validated by the destructive testing for more than 50 specimens.

통계적 실험계획에 의한 PECVD로 증착된 실리콘 산화막의 특성 분석

李晟準,金洸範,崔鑛泉,漢秀一,尹知原,金劉邏,朴宰賢,洪尙眞 명지대학교 산업기술연구소 2006 産業技術硏究所論文集 Vol.25 No.-

According as the current needs of low temperature in semiconductor manufacturing process, PECVD using low temperature and high deposition rate is becoming more of a concern. However, PECVD equipment has the defect possibility on the interface between substrates and gate oxide layer, because ions or electrons with much high energy clash the interface. In this study, we embarked on the experiment with Statistical Design of Experiment and then also analyze which parameters influence on the characteristic of silicon dioxide filems. We finally made a constructive proposal for process optimization conditions.

G292 세포에서 세포막 신장으로 활성화되는 K^+통로의 특성

이상국,정동근,서덕준,박수병 대한치과교정학회 2000 대한치과교정학회지 Vol.30 No.2

본 연구에서는 인체 골종양에서 유래한 G292세포를 이용하여 압력으로 세포막을 신장(stretch)시켰을 때 K+ 통로의 전기적 활성 변화를 연구하였다. 배양된 세포에서 유리전극을 이용하여 세포막 내측이 유리전극의 외부로 향하도록 inside-out patch를 얻어 단일이온통로전류를 막전압고정법 (patch clamp recording)으로 기록하였다. G292세포의 세포막 내외에 140 mM KCl용액이 있는 상태에서 유리전극내 전압을 -80 mV로 고정했을 때 전도성이 270±27 pS, 113±12 pS, 48±8 pS인 3가지 종류의 K+통로를 관찰하였다. 전도성이 낮은 48 pS의 K+ 통로는 모든 세포막에서 관찰하였으며 270 pS 및 113 pS의 K+ 통로는 일부 세포에서만 관찰하였다. 48 pS의 K+ 통로는 세포막 외측에 음의 전압을 가하면 활성화되고 양의 전압을 가하면 활성화되지 않는 외향성 정류특성을 보였다. 세포막 외측에 음압을 가하면 48pS의 K+통로는 활성화되었으며 이온 통로가 열리는 확률(Popen)이 가하는 압력에 비례하여 증가하였다. 이러한 결과는 G292세포주에 3가지 종류의 K+통로가 존재하며 전도성이 낮은 48pS의 K+통로만이 세포막 신장에 의하여 직접적으로 활성화되는 특성을 보였다. 이러한 K+ 통로의 활성화는 세포가 기계적 자극을 받아 세포막이 신장되면 세포막전압을 과분극시키며 조골세포에서 기계적 강수기로서의 기능을 수행하여 조골세포의 골개조에 관여할 것으로 추측된다. K+-selective ion channels were studied in excised inside-out membrane patches from human osteoblast-like cells (G292). Three classes of K- channels were present and could be distinguished on the basis of conductance. Conductances were 270±27 pS, 113± 12 pS, 48±8 pS according to their approximate conductances in symmetrical 140 mM KCI saline at holding potential of -80 mV. It was found that the small conductance (48 pS) K+ channel activation was dependent on membrane voltage. In current-voltage relationship, small conductance K+ channel showed outward rectification, and it was activated by the positive potential inside the membrane. In recordings, single channel currents were activayed by a negative pressure outside the membrane. The membrane pressure increased Popen of the K+ channel in a pressure-dependent manner. In the excised-patch clamp recordings, G292 osteoblast-like cells have been shown to contain three types of K+ channels. Only the small conductance (48 pS) K+ channel is sensitive to the membrane stretch. These findings suggest that a hyperpolarizing current, mediated in part by this channel, may be associated with early events during the mechanical loading of the osteoblast. In G292 osteoblast-like cells, K+ channel is sensitive to membrane tension, and may represent a unique adaptation of the bone cell membrane to mechanical stress.