• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05a
• /
• pp.224-228
• /
• 2002

In this study, the piezoelectric ceramics PZT powder was synthesized by the Wet-Dry combination method. Flexible 1-3 type composite specimens were fabricated with the piezoceramics PZT filler phase and Eccogel polymer matrix phase. This paper represents the pulse-echo response of the 1-3 type composite transducer to check it out to investigate a basic property regarding a level limit switch. The acoustic impedance of 1-3 type composite was improved than that of single phase PZT ceramics. The pulse-echo response of transducer fabricated with the self-made 1-3 type composites resonator was better than that of the solid PZT transducer.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.3
• /
• pp.324-337
• /
• 1999

In this work, a new 3-PSP type spatial 3-degree-of-freedom parallel mechanism is proposed. And a 6 DOF hybrid manipulator which consists of a 3-PPR type planar 3 DOF parallel mechanism and a new 3-PSP type spatial 3-degree-of-freedom parallel mechanism is proposed. Both 3 DOF mechanism modules have closed-form forward position solutions and particularly, 3-PSP spatial module has unique forward position solution. Firstly, the closed-form position analysis and first-order kinematic analysis for the proposed 3-PSP type module are carried out, and the first-order kinematic characteristics are examined via maximum singular value and the isotropic index of the mechanism. It is shown through these analyses that the mechanism has excellent isotrpic property throughout the workspace. Secondly, position and kinematic analysis of the 3-PPR planar module are briefly described. Thirdly, the forward position analysis for the 3-PPR 3-PSP type 6 degree-of-freedom hybrid mechanism consisting of a 3-PPR planar module and a 3-PSP spatial module is performed along with the analysis of the workspace size and first-order kinematic characteristics. The kinematic characteristics of the proposed hybrid manipulator are compared to those of geometrically similar Stewart manipulator.

• Proceedings of the IEEK Conference
• /
• 2002.06b
• /
• pp.41-44
• /
• 2002

The Semiconductor Industrial are developed after 1940. It was called “Rice of Industrial”. It needs great effect in Electronics. It was developed highly in recent several years with semiconductor manufacturing equipments. Semiconductor manufacturing devices are developed “In-line” type in the first stage. But It was non-effective in modem many type process. Because this reason, Cluster type manufacturing equipments are proposed. Cluster have ability of many-type-process and effective-scheduling by circular type process chamber In this paper. we propose a real-time 3D monitoring and simulation of this semiconductor manufacturing equipments. By proposed monitoring method, we have capability real visual maintanance & virtual simulation. This effective visual 3D monitoring could apply another dangerous environment in entire industrial.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2002.11a
• /
• pp.434-444
• /
• 2002

본 논문에서는 기존의 RF 여파기가 대역 내에서만 정합이 되는 특성을 개선하여 대역 외에서도 50$\Omega$ 정합 특성을 가지는 여파기 설계 기술을 제안하였다. 대역 외에서 정합 시켜 주는 방법으로 결합기와 대역 통과 여파기로 구성된 Balance Type과 결합기와 대역 저지 여파기로 대역 통과 여파기 특성을 가지는 Reflection Type을 제시하여 그 특성을 확인하였다. 각각의 형태는 광대역 90도 3-㏈ 결합기를 사용한 것으로 결합기의 대역폭과 진폭 및 위상 오차에 따라 저지 대역에서의 정합 특성이 좌우되며, 이에 광대역의 3-㏈ 결합기를 설계 및 적용하여 광대역의 반사 손실 개선 효과를 얻을 수 있었다. 제작 결과 Balance type의 경우 1.2 GHz~2.6GHz까지 대역 내에서 -10㏈에서 -15 ㏈의 반사 손실 특성을 가지고 대역 저지 특성이 우수하며, Reflection type은 DC에서 3.3GHz까지 반사손실이 -15 ㏈ 내외로 광대역 정합 특성을 가진다. 특히, 저주파 반사 특성이 우수하여 저주파 발진 가능성이 큰 회로 설계에 유용하다.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1993.04a
• /
• pp.112-112
• /
• 1993

바이러스 치료제 개발을 위하여 합성된 핵산유도체 11개에 대한 in vitro 항바이러스 약효검색을 수행하였다. 검색대상 바이러스로서 외피보유 DNA 바이러스인 human herpesvirus에 속하는 herpes simplex virus type 1과 type 2에 대해서는 Vero 세포체계에서 3일 후 CPE 저해정도를 MTT 검색법으로 cytomegalovirus에 대해서는 HEL 세포체계에서 7일 후 Giemsa 염색법으로 약효를 측정하였다. 외피비보유 RNA 바이러스인 picornavirus에 속하는 poliovirus type 1과 type 3과 coxsackie B virus type 3에 대한 약효를 HeLa 세포체계에서 2일 후 CPE 저해정도를 MTT 검색법으로 측정하였다. 아울러 selectivity index를 구하기 위하여 Vero와 HeLa 세포에 대한 약물자체의 독성인 cytocidal effect를 MIT 검색법으로 측정하였다. 그 결과 항 herpesvirus 약효는 어떤 물질에서도 발견되지 않았으나 한 물질이 poliovirus type 1과 3에 대하여 selectivity index 10정도 (CC$_{60}$ 38 ug/ml, EC$_{50}$ 1-4 ug/ml)를 나타내었고 자세한 기작은 좀 더 조사할 필요가 있다.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.6
• /
• pp.78-85
• /
• 2007

In this study, we performed finite element analysis for the design of a medical centrifuge and two-types of centrifuge were compared with each other. The types of centrifuge are 2-arm straight type and 3-arm type. Structural analysis was done with respect to the change of the rotational speed of the rotor of a centrifuge. When the rotor of centrifuge was rotated, the von Mises stress of 2-arm straight type-rotor was compared with the von Mises stress of 3-arm type. The margin of safety was estimated from the result. We found the critical speed of centrifuge from the campbell diagram by modal analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.409-416
• /
• 2006

The seismic characteristics with 3-Dimensional Floor Isolation System have been studied using a shaking table system. In this study, we made two kind of floor system (Type I, Type II) and several seismic tests with and without isolation system were conducted to evaluate 3-Dimensional Floor Isolation Effectiveness. Both type have showed large reduction effectiveness in acceleration, response spectra but Type II have showed lower acceleration and lower first mode in response spectra, compared to type I. On the basis of test results and consideration of application, it is found that type II is more suitable for floor model of main control room of Nuclear Power Plant.

• Imaging Science in Dentistry
• /
• v.51 no.4
• /
• pp.383-388
• /
• 2021

Purpose: The aim of this study was to evaluate the root canal morphology of mesial roots of mandibular first molars. Materials and Methods: Forty extracted mandibular first molars were used in this study. The morphological examination of root canals was conducted in accordance with the Vertucci classification using micro-computed tomography (micro-CT). Any aberrant root canal configurations not included in the Vertucci classification were recorded, and their frequency was established using descriptive statistics. Intra-observer reliability was assessed using the Wilcoxon signed-rank test, while inter-observer reliability was assessed using the Cohen kappa test. Significance was evaluated at the P<0.05 level. Results: The mesial roots of mandibular first molars had canal configurations of type I (15%), type II (7.5%), type III (25%), type IV (10%), type V (2.5%), type VI (7.5%), and type VII (7.5%). The images showed 10 (25%) additional configuration types that were not included in the Vertucci classification. These types were 1-3-2-3, 1-2-3-2-3, 2-3-1, 2-3, 1-2-3-1, 2-1-2-3, 3-2-1, 1-2-3-1, 2-3-2-3, and 1-2-1-2-1. The intra-observer differences were not statistically significant(P>0.05) and the kappa value for inter-observer agreement was found to be 0.957. Conclusion: Frequent variations were detected in mesial roots of mandibular first molars. Clinicians should take into consideration the complex structure of the root canal morphology before commencing root canal treatment procedures to prevent iatrogenic complications. Micro-CT was a highly suitable method to provide accurate 3-dimensional visualizations of root canal morphology.

• Journal of the Korean Dietetic Association
• /
• v.24 no.3
• /
• pp.212-230
• /
• 2018

The purpose of this study was to investigate the effects of job stress on job satisfaction according to interpersonal relationship type among school dieticians and nutrition teachers. The online survey was conducted from Oct. 26th to Nov. 7th, 2017 in 2,000 randomly selected dieticians and nutrition teachers in the capital area. A total of 453 collected questionnaires were used for analysis. SPSS v.21.0 Statistical Package Program was used for the statistical process. For the results regarding interpersonal relationship type of dieticians, open-type (73.3%) was the highest, followed by self-assertive-type (23.0%), isolated-type (2.6%), and careful-type (1.1%). Regarding overall job satisfaction, 'human relation' was the highest, followed by 'job itself', 'working environment', and 'personal rating & welfare system', in that order. According to interpersonal relationship type, in the case of 'open-type' or 'careful-type', job satisfaction was relatively high. Regarding overall job stress, 'job demand' was the highest, followed by 'lack of reward', 'organizational system', 'interpersonal conflict', 'occupational climate', 'job insecurity', and 'insufficient job control', in that order. In accordance with interpersonal relationship type, overall job stress index was high in terms of 'self-assertive-type' or 'careful-type'. For the results of analyzing the correlation between job satisfaction and job stress index, all areas showed statistically significant negative correlations. Multiple regression analysis was performed to study the effects of job stress on job satisfaction mediating interpersonal relationship type. Job stress had different effects on job satisfaction in terms of 'open-type' and 'self-assertive type'. In conclusion, different strategies are needed for dieticians with different interpersonal relationship types to improve job satisfaction and to reduce job stress.

• Electrical & Electronic Materials
• /
• v.9 no.2
• /
• pp.146-151
• /
• 1996

PZT powders were prepared by the molten salt synthesis method. The porous PZT ceramics were made from a mixture of PZT and polyvinylalcohol(PVA) by BURPS(Bumout Plastic Sphere) technique. The 3-3 type composites were fabricated by impregnating an sintered porous PZT ceramics with various polymer matrices. The relative permittivity of 3-3 type composite specimens was shown 860-1,100 smaller than that of solid PZT ceramics(2,100), and the dissipation factors of composite specimens were about 0.02 to 0.03. The piezoelectric coefficient d$_{33}$ of composite specimens(285-328*10$^{12}$ C/N) was comparable with that of single phase PZT specimens(364*10$^{-12}$ C/N). The thickness mode coupling factor k$_{t}$(O.5-0.6) of composite specimens was comparable with that of single phase PZT specimens(k$_{t}$-0.7), and the mechanical quality factor of composite specimens was smaller than 10, and thus these 3-3 type composite specimens would be believed as a good candidates for broad band transducer applications.ons.