• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.6
• /
• pp.820-832
• /
• 1986

In contrast to conventional liquid phase epitaxy of GaAs, surface kinetics limited growth is predominant in selective liquid phase epitaxy. For the stripe openings in the high-index crystal-lographic directions, the well-known facet formations and the decompositions into the low index planes or smooth circular surfaces are observed depending on the growth kinetics. For the low index direction stripe, surface kinetics limited growth is evident. By a numerical calcualtion we show that these phenomena are due to the enhanced masstransport by two dimensional diffusion and growth rate anisotropy which is found to be very stdrong with cusped minima for some singular planes in the solution growth as well as in vapor phase epitaxy. Morphological stability is briefly treated in terms of diffusion and its implications on device application are stated. Tese phenomena may be common to III-V compound semiconductors as well as GaAs.

• Journal of Korean Dental Hygiene Science
• /
• v.3 no.2
• /
• pp.9-18
• /
• 2020

This study analyzed 183 for dental hygienists working at dental hospitals and clinics in Daegu to survey organizational socialization of them. The adversity index of the study subjects averaged 58.60±9.16 points out of a total score of 100, with the highest individual initiative of 16.58±3.09 points, and a low of 13.86±3.66 points for continuity of the situation. Organizational socialization averaged 123.40±12.82 points out of 190, with the highest personal characteristics of 30.37±3.71 points, and the lowest occupational identity of 10.34±1.94. The adversity index of the participants was significantly higher in graduate school or higher (F=3.112, p=0.047), the lower the intensity of their work (F=2.860, p=0.060), and the more often the degree of turnover (F=5.196, p<0.006). In organizational socialization, age (F=9.290, p<0.001), educational background (F=8.655, p<0.001), and higher position (F=5.425, p=0.005) were significantly higher when working in hospitals (F=4.534, p=0.012). The higher the position (F=5.425, p=0.005), the higher the work experience (F=5.320, p=0.002), the lower the turnover (F=22.935, p<0.001), and the highrer the intensity of the work(F=7.02, p<0.001). The study subjects' organizational socialization showed a significant correlation with the adverse event index (r=0.395, p<0.000). The regression analysis using organizational socialization as a dependent variable showed that the degree of turnover (β=0.300, p<0.001) had a significant effect on organizational socialization. The total explanatory power of this variable was 41.6%, with significant effects on individual initiative (β=0.255, p<0.000) and personal control (β=0.180, p<0.009) among the adverse events index. The above findings confirmed that a high adverse event index of dental hygienists has the effect of increasing organizational socialization. Dental hygienists' adversity index is average, meaning they live a smooth life in smooth conditions, however, when major adversity arises, organizational socialization is highly necessary. In addition, to strengthen the organizational socialization of new dental hygienists, as well as experienced dental hygienists, a customized program should be administered to raise the adverse index of dental hygienists, and provide a human management tool through regular confirmation of the program.

• Geomechanics and Engineering
• /
• v.18 no.4
• /
• pp.391-406
• /
• 2019

The aim of this paper was to study the influence of the footing shape and the effect of the roughness of the foundation base on the bearing capacity of shallow foundations on rock masses. For this purpose the finite difference method was used to analyze the bearing capacity of various types and states of rock masses under the assumption of Hoek-Brown failure criterion, for both plane strain and axisymmetric model, and considering smooth and rough interface. The results were analyzed based on a sensitivity study of four varying parameters: foundation width, rock material constant (mo), uniaxial compressive strength and geological strength index. Knowing how each parameter influences the bearing capacity depending on the footing shape (circular vs strip footing) and the footing base interface roughness (smooth vs rough), two correlation factors were developed to estimate the percentage increase of the ultimate bearing capacity as a function of the footing shape and the roughness of the footing base interface.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.221-228
• /
• 2003

The stress corrosion index of Kumamoto andesite are evaluated by two types of testing method. One is the uniaxial compression test under various water vapor pressures, and the other is the double torsion (DT) test under a constant water vapor pressure. For the uniaxial compression tests, the uniaxial compressive strength increases linearly with decreasing water vapor pressure on the double logarithmic coordinates. As the results, the stress corrosion index obtained is estimated 44. On the other hand, in the DT test, the relaxation (RLX) test and the constant displacement rate (CDR) test were conducted. For the CDR test, as the displacement rate of loading point increases, the crack velocity increases. However, the fracture toughness is constant regardless of the change in displacement rate and the average fracture toughness is evaluated $2.07MN/m^{3/2}$. For the RLX test, the crack velocity-stress intensity factor curves are smooth and linear. The stress corrosion index estimated from the curves is 37. Comparing stress corrosion indexes in the uniaxial compression test and the DT test, there is no significant difference in these values, and they are considered to be in coincident each other regardless of testing methods. Therefore, it is concluded that stress corrosion is one of material constants of rock.

• ETRI Journal
• /
• v.36 no.1
• /
• pp.69-79
• /
• 2014

The scheduling scheme in packet switching networks is one of the most critical features that can affect the performance of the network. Hence, many scheduling algorithms have been suggested and some indices, such as fairness and latency, have been proposed for the comparison of their performances. While the nature of Internet traffic is bursty, traditional scheduling algorithms try to smooth the traffic and serve the users based on this smoothed traffic. As a result, the fairness index mainly considers this smoothed traffic and the service rate as the main parameter to differentiate among different sessions or flows. This work uses burstiness as a differentiating factor to evaluate scheduling algorithms proposed in the literature. To achieve this goal, a new index that evaluates the performance of a scheduler with bursty traffic is introduced. Additionally, this paper introduces a new scheduler that not only uses arrival rates but also considers burstiness parameters in its scheduling algorithms.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.654-655
• /
• 2008

In order to investigate the availability of tire airborne noise for vehicle road noise development, We measured the noise in condition of smooth road and coarse road. The correlation coefficient was analyzed using the articulation index of the tire airborne noise and the vehicle road noise. It has been found that the correlation between the tire airborne noise and the vehicle road noise is positively strong.

• Proceedings of the KIEE Conference
• /
• 1999.07b
• /
• pp.659-661
• /
• 1999

In this paper, we proposed a simple neural network-based parameter tuning algorithm, which could find the gradients of a certain performance index in the PID parameter spaces. In this process, we had to know the dynamics between input and output of the plant, and we used the Back Propagation Neural network to identify them. To make the parameter updating fast and smooth, we constructed the performance index as the sum of past N-squared plant errors, and applied a batch mode algorithm to update parameters. We performed several experiments with a DC Motor to show the validity of the proposed algorithm.

• 한국가시화정보학회:학술대회논문집
• /
• 2007.11a
• /
• pp.123-127
• /
• 2007

The effect of axial slit wall of outer cylinder on Taylor-Couette flow was experimentally investigated. The axial slits were azimuthally located along the inner wall of outer cylinder and the number of slits was 6, 9 and 18. The radius ratio and aspect ratio of the experimental models was 0.825 and 48, respectively. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the effect of slit on the flow transition is increased as the number of slit increased. When the model has 6 slits, there were hardly the effect of axial slit wall and the flow transition happened at the same Reynolds number of plain smooth wall model case.

• Journal of Power System Engineering
• /
• v.5 no.2
• /
• pp.30-35
• /
• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one wall roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at $e/D_e=0.0476$, P/e=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicate that the triangular type rib has a substantially higher efficiency index than any other ones in the range we studied.

• Journal of the Korean Society for Precision Engineering
• /
• v.33 no.8
• /
• pp.655-660
• /
• 2016

Self-closing drawers are used in high-end products, such as furniture, home appliances, and a range of other storage devices. In this study, a self-closing mechanism is proposed. A system consisting of a friction latch, constant force spring, rotary damper with rack, and pinion is developed. The retracting drawer can be latched at any position and can be reactivated by simple touch. The constant force spring and rotary damper offer smooth closing action. The ergonomic quality of the closing action is quantified by an index based on velocity-time behavior. The effects of various design parameters are analyzed with a dynamics model and experimentally validated by prototype testing.