• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.228.2-228.2
• /
• 2015

We have developed a TOF-MEIS system using 70~100 keV He+. A TOF-MEIS system was designed and constructed to minimize the ion beam damage effect by utilizing a pulsed ion beam with a pulse width < 1 ns and a TOF delay-line-detector with an 120 mm diameter and a time resolution of 180 ps. The TOF-MEIS is an useful tool for interfacial analysis of the composition and structure of nano and bio systems. Our recent applications are reported. We investigated the effect with Polyaspartic Acid (pAsp) and Osteocalcin on the initial bone growth of calcium hydroxyl appatite on a carboxyl terminated surface. When pAsp is not added to the self-assembled monolayers of Ca 2mM with Phosphate 1.2 mM, the growth procedure of calcium hydroxyl appatite cannot be monitored due to its rapid growth. When pAsp is added to the SAMs, the initial grow stage of the Ca-P can be monitored so that the chemical composition and their nucleus size can be analyzed. Firstly discovered the existence of 1-nm-sized abnormal calcium-rich clusters (Ca/P ~ 3) comprised of three calcium ions and one phosphate ion. First-principles studies demonstrated that the clusters can be stabilized through the passivation of the non-collagenous-protein mimicking carboxyl-ligands, and it progressively changes their compositional ratio toward that of a bulk phase (Ca/P~1.67) with a concurrent increase in their size to ~2 nm. Moreover, we found that the stoichiometry of the clusters and their growth behavior can be directed by the surrounding proteins, such as osteocalcin.

• Korean Journal of Child Studies
• /
• v.32 no.3
• /
• pp.221-239
• /
• 2011

The purpose of study is to understand how a principal of a child-care center and parents accept different episodes and experiences in admission counselling and their use of metaphorical expressions about this, and to illuminate the current state of play by examining the requirements of parents in selecting a child-care center. The subjects were 10 principals of private child-care centers located in the Gyeongsangbuk province of Korea, and the research materials for episodes and metaphors were collected and analyzed by means of in-depth and telephone interviews during an application period. In terms of the overall climate of the admission counselling, as shown in the various episodes, our results indicated that an increase of parents' demands occurred through a primarily consumer-centered environment, and the sudden increase in a fathers' participation, the inside circumstances of admission counselling in progress throughout the year, the non-existence of respect and credibility and the continuity of conflicts and were all observed to co-exist. In terms of the emotional meaning of counselling via metaphors, the following emotions could be inferred; hopelessness, anger, lethargy, stress, fear and eagerness. It is anticipate that this study will make a meaningful contribution to better illuminating and improving the current climates of here and now admission counselling.

• The Journal of the Korean dental association
• /
• v.55 no.2
• /
• pp.116-127
• /
• 2017

Objectives : The aim of this study was to evaluate the cumulative survival rates of the implants placed into grafted sinus and determine the effect of age, gender, smoking, and systemic disease on the implant cumulative survival rates. Materials and Methods : The retrospective study was performed on 51 implants placed in 26 patients by one dentist at the Dental Implant Center, Seoul National University Dental Hospital in the years 2000-2010. The cumulative survival rates were calculated by the Kaplan-Meier method. The differences within the factors were analyzed using log-rank test and the correlations between the factors and implant survival rates were analyzed using Cox proportional hazard model. Results : 1. Among the total of 51 implants placed in 26 patients, 7 implants failed and 44 implants remained stable. The 1-year, 5-year, and 10-year cumulative survival rates were 92%, 88%, and 85%, respectively. 2. Patients in their 50s and in their 70s showed statistically significant difference in the cumulative survival rates (P < 0.05). Gender and the existence of systemic disease did not show significant results. 3. In the implant treatment, smokers showed 7.5 times higher risk of implant failure than non-smokers (P < 0.05). Conclusion: Implants installed in combination with sinus elevation can be considered as a reliable treatment method.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.4
• /
• pp.41-48
• /
• 2009

A flexible pipe was buried 10cm below the ground formed with standard sand to observe changes in the shape of the pipe according to the behavior of ground at each relative density. Changes in the shape of the pipe in each ground were observed to examine the behavior of the pipe under the state of reinforced ground after installing geogrid under the pipe. Ground reinforced using geogrid formed tensile force on the reinforcement material with increase in the vertical load and showed reduction in settlement under identical vertical load with existence of reinforcement. Distributions of ground deformation of 100% relative density and 70% relative density had clear difference. Reinforced ground with 70% density converged to the ground reaction of final settlement of non-reinforced ground with 100% density at final settlement of 100 mm. Because the shape of lower part strain of the buried pipe is similar to that of un-reinforced ground with relative density of 100%, reinforcement effect by geogrid in soft ground can be anticipated.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.25 no.4
• /
• pp.371-374
• /
• 1999

The treatment of adults with dentofacial deformities is frequently complicated by existence of discrepancies in transverse dimension. Control of the transverse dimension through surgical technique is now a valuable treatment consideration in non-growing patients. Proper diagnosis of relative and absolute maxillary transverse deficiency is imperative prior to surgical intervention. Therapeutic purpose should be implemented accordingly to facilitate correction of transverse discrepancies concomitant with treatment objectives in sagittal dimension in order to provide the patient with the most stable and functional result possible. Concomitant surgical correction of narrow palate require less treatment time, treatment cost and post-treatment relapse is less than to do only orthodontic therapy. This report is concerned with rapid palatal expansion by a combination of corticotomy and orthodontic treatment.

• The Journal of Korean Academy of Sensory Integration
• /
• v.4 no.1
• /
• pp.1-15
• /
• 2006

Objective : The purpose of this study was to examine the correlation between handwriting skills and praxis. Method : Participants consisted of 50 normal children who were the second-grade students at an A elementary school in Kim-hae. They didn't have a visual dysfunction, an auditory dysfunction, and a disease or an injury in arms and hands. They could follow examiners' directions properly. They were administered the Postural Praxis and the Praxis on Verbal Command of the Sensory Integration and Praxis Tests(SIPT)(Ayres, 2000) and the handwriting skill test which was made with reference to foreign literatures. It was conducted from October 19, 2004 to December 17, 2004. The data were analyzed with non-paired t-test, ANOVA, and Pearson correlation coefficient. Results : 1. Total handwriting score and praxis according to gender of children showed the statistically significant differences(p<0.05). 2. Total handwriting score correlated with praxis(p<0.05) and handwriting speed did not correlate with praxis. 3. Postural Praxis and Praxis on Verbal Command according to handwriting groups showed the statistically significant differences(p<0.05). 4. Among the standards of the handwriting skill test, accuracy of letter form, identity of letter size, spacing between letters and words, placing text on lines, error existence, and letter out of regular square correlated with the Postural Praxis(p<0.05), and accuracy of letter form, identity of letter size, and placing text on lines correlated with the Praxis on Verbal Command(p<0.05). Conclusions : The correlation between handwriting skills and praxis will help occupational therapists to provide fundamental and various treatment programs for children who are referred for the poor handwriting. But more studies in handwriting skills and praxis are necessary to decide which component of handwriting skills is related to praxis.

• Composites Research
• /
• v.13 no.3
• /
• pp.9-20
• /
• 2000

Free vibration characteristics of a cantilevered laminated composite beam with multiple non-propagating transverse open cracks are investigated. In the present analysis a special ply-angle distribution referred to as asymmetric stiffness configuration inducing the elastic coupling between chord-wise bending and extension is considered. The multiple open cracks are modelled as equivalent rotational springs whose spring constants are calculated based on the fracture mechanics of composite material structures. Governing equations of a composite beam with open cracks are derived via Hamilton's Principle and Timoshenko beam theory encompassing transverse shear and rotary inertia effect is adopted. The effects of various parameters such as the ply angle, fiber volume fraction, crack numbers, crack positions and crack depthes on the free vibration characteristics of the beam with multiple cracks are highlighted. The numerical results show that the existence of the multiple cracks in an anisotropic composite beam affects the free vibration characteristics in a more complex fashion compared with the beam with a single crack.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.9
• /
• pp.4188-4206
• /
• 2016

Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

• Journal of Soil and Groundwater Environment
• /
• v.17 no.2
• /
• pp.1-6
• /
• 2012

Total Economic Value (TEV) provides a framework to estimate the economic value of water resources including groundwater with multiple applications to natural resource economics and environmental economics. Crucial to the application of economic analysis to natural resources are techniques to value the resources as an economic value that is expressed in monetary terms. On the other hand, the aim of TEV estimation is to determine the economic value of water resources including 'use' with production and recreation and 'non-use' such as existence values. TEV is used to assess the economic value of water resources for the multiple goods, and environmental 'services' that are provided by a water resource and also used to assess options for water use, for example balancing production values provided by water resource use against the cost of resource degradation by that use. The value of TEV can be assessed over time where pollution or unsustainable use may reduce the economic value of an environmental asset. Therefore, values are used to assess options of resource use, sometimes leading to policies on resource conservation or allocation. In conclusion, the application of TEV would be well adjusted over Jeju Island where groundwater resources account for more than 98% water resources and the budget of water demand/supply shows disparity over the Island.

• Journal of Korea Water Resources Association
• /
• v.34 no.1
• /
• pp.45-55
• /
• 2001

Transcritical flow is a term intended to denote the existence of both supercritical and subcritical flows within a computational domain. The major problems that need to be addressed while modeling transcritical flows include handling the differing features of signal propagation in subcritical and supercritical flow regions and maintaining conservation. The present study proposes the implicit ENO method as a high-resolution scheme for transcritical flow. This implicit ENO scheme is based on the ENO method, a new class of uniformly high-order-accurate essentially non-oscillatory implicit scheme, which has the advantage of unconditional stability. The implicit ENO scheme has not been used for the transcritical flow in open channel until now. As a result of application to the hypothetical dam-break flow, the implicit ENO scheme was ploved to produce accurate results with good robustness even though in the case of verb strong shock wave.