• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.366-370
• /
• 2002

GaAs has become a very popular material for the fabrication of high frequency, low noise and microwave power devices. GaAs devices are also well suited for high temperature operation because of the large band gap of this material. The standard GaAs technology and device structures have to be modified for stable operation at high temperature. In this paper, AlGaAs/GaAs HBT considering stable ohmic contact at high temperature as well as thermal effect such as self-heating effect are introduced. All the data obtained study will be used as input data for the simulator and the result will be compared with an analytical model available in this study,

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1038-1041
• /
• 2003

The magnetic suspension system is used in many areas, because it has great advantages. such as no friction, no noise, no lubrication and so on, but it is a unstable system in natural. It must have a feedback control with the position is measured for a stable levitation. There are an eddy-current sensor, a capacitive sensor, an inductive sensor, and an optical sensor with a laser as the sensor which measures displacements without contact. Among them, an inductive sensor is made with lower price than others. And it has a good linearity. In this paper, a magnetic circuit leads a linear equation between an input as a displacement and an output as a voltage. Experiments establish that voltage change according to displacement is linear. This paper presents the preliminary study of an inductive position sensing for self-sensing magnetic suspension system.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.2
• /
• pp.100-107
• /
• 1998

Diamond wheels with fine grains and multi-porous structures are newely trial developed for smoothing and mirror finishing materials. Grinding wheel must have performed both to remove tool marks efficienitly and to contact elastically with curved surfaces, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, Diamond grains are bonded by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures are developed to increase the flexibility of the grinding wheel, and to induce self-sharpening by increasing contact pressure between the grinding wheel and workpiece surfaces. In this paper, melamine-bonded diamond wheels try to manufacture, then the forming method of grinding wheel are suggested, and the grinding characteristics of melamine-bonded diamond grinding wheel are also illustrated.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.12
• /
• pp.2172-2178
• /
• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.

• Journal of Mechanical Science and Technology
• /
• v.14 no.10
• /
• pp.1081-1088
• /
• 2000

In this paper, a compliance control strategy for robot manipulators that employs a self-adjusting stiffiness function is proposed. Based on the contact force, each entry of the diagonal stiffness matrix corresponding to a task coordinate in the operational space is adaptively adjusted during contact along the corresponding axis. The proposed method can be used for both the unconstrained and constrained motions without any switching mechanism which often causes undesirable instability and/or vibrational motion of the end-effector. The experimental results involving a two-link direct drive manipulator interacting with an unknown environment demonstrates the effectiveness of the proposed method.

• Journal of the Korean Home Economics Association
• /
• v.46 no.3
• /
• pp.117-126
• /
• 2008

The purpose of this study was to identify and assess influential social adjustment factors in children who live in child care institutions. To do this, correlation and regression analysis in Structural Equation Model were carried out on 326 children from 12 child care institutions. The findings are as follows; Social adjustment in children living in child care institutions were deemed better based on higher self-esteem, more maintenance of contact with parents, more positive caring environment within institutions, higher support of fellow school children, and more pro-social charactes of school peers. The influence of each variables on social adjustment was indicated to be highest in institutions with a caring environment. In conclusion, self-esteem, pro-social charactes of school peers, support of fellow school children, and contact with parents (in that order) were deemed most influential to social adjustment.

• Asia pacific journal of information systems
• /
• v.15 no.4
• /
• pp.61-87
• /
• 2005

This paper has two primary objectives: (1) to propose a comprehensive theoretical model that incorporates valuable insights from two complementary streams of research, and (2) to empirically test the model that explain the task-media fit and satisfaction of customer contact center users. The comprehensive model was tested using LISREL analysis on the sample of 232 users who have experience with the customer contact center. The model was supported in customer contact center context, accounting for 29% of the variance in the task-media fit, 53% of the variance in the perceived ease of use, 61% of the variance in the perceived usefulness, and 52% of the variance in the user satisfaction. The results showed that the task-media fit, the perceived ease of use, and the perceived usefulness play a significant role in influencing the user satisfaction of the customer contact center. In addition, task analyzability, media richness, media interactivity, and self-efficacy were found to influence the task-media fit. The paper concludes with discussions and implications for researchers and practitioners.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.6 s.261
• /
• pp.679-685
• /
• 2007

Superhydrophobic surface, with a water contact angle greater than $150^{\circ}$, has a self-cleaning effect termed 'Lotus effect'. This surface is created by the combination of rough surface and the low surface energy. We proposed square pillar and square shapes to control surface roughness. Microstructure arrays are fabricated by DRIE(Deep Reactive Ion Etching) process and followed by PPFC(Plasma Polymerized Fluorocarbon) deposition. On the experimental result, contact angle at square pillar arrays is well matched with Cassie's model and largest contact angle is $173.37^{\circ}$. But contact angle of square pore shape arrays is lower than Cassie's theoretical contact angle about $5{\sim}10%$. Nevertheless, square pore arrays have more rigidity than square pillar arrays.

• Journal of Korean Biological Nursing Science
• /
• v.25 no.1
• /
• pp.63-72
• /
• 2023

Purpose: This study investigated the knowledge, attitudes, and perceptions of a safe environment, as well as self-reported and observed compliance with the use of personal protective equipment (PPE), among intensive care unit (ICU) nurses. Methods: This study was conducted in October 2021 with 55 nurses working in the medical and surgical ICUs of a general hospital in Seoul. A self-reported questionnaire and an observational tool for compliance with the use of PPE were used to collect data. Results: Except for masks, the observed compliance for all other PPE types was lower than the self-reported compliance. Male nurses showed significantly higher observed compliance than female nurses. Self-reported compliance with PPE use, including "when there is a possibility of contact with objects contaminated with blood or body fluids, mucous membranes, damaged skin, or contaminated skin" (r = .23, p = .015) and "when there is a possibility of contact with blood, body fluids, secretions, or exudates" (r = .27, p = .004) showed significant correlations with knowledge of PPE. In the results for self-reported compliance with PPE use, gown use had a significant correlation with knowledge (r = .24, p < .001) and perceptions of a safe environment (r = .15, p = .016) for PPE, and gloves showed significant correlations with attitudes (r = .14, p = .024) and perceptions of a safe environment (r = .18, p = .003). Conclusion: The observed compliance with PPE use tended to be lower than the self-reported compliance among ICU nurses. It is necessary to develop and apply an effective educational program that can enhance improve actual compliance with PPE use among intensive care unit nurses.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.10a
• /
• pp.219-224
• /
• 1997

In surface grinding, the contact between the grinding wheel and the workpiece introduces heat and resistance, which restrict the self-dressing of the grits and result in burrs and cracks on the workpiece. Therefore, before or during th grinding wheel for more accurate performance. In order to determine the dressing time monitoring method of grinding wheel in surface grinding, a three-dimensional computer simulation of the grinding operation has been attempted based on the contact mechanism and surface-shaping system between the grinding wheel and the workpiece. The optimal dressing time is determined based on the amount of the grain wear and work surface roughness.