• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• Journal of the Korean GEO-environmental Society
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• v.14 no.12
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• pp.31-41
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• 2013

The damage caused by lateral movement occurs frequently on site where abutment or retaining wall was built on soft ground along with embankment behind and the study on stability of abutment against lateral movement has been mostly focused on soft ground. However lateral movement occurs not only on soft ground but also on embankment slope which causes the impact on structure. The bridges built in Korea are mostly on mountainous area than soft ground. This study is intended to analyze the ground behavior resulting from lateral movement using finite element analysis method to the section as well as propose the basic data for abutment design on embankment slope through the analysis of the outcome of reinforcement method. As a result, when it comes to the reinforcement with soil surcharge and stabilized pile in slope, lateral movement was reduced by 4~30% and displacement on bearing shoe on abutment was reduced by 2~13%. On the contrary, when reinforced with EPS, lateral float was reduced by 97% and maximum horizontal displacement of bearing shoe on abutment was reduced by 95%. Thus, it's necessary to identify the design technique which is applicable to domestic condition through additional tests and more reliable study using numerical analysis and comparing the measured values shall follow.

• Journal of the Korean earth science society
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• v.37 no.3
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• pp.162-172
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• 2016

Since the Northridge earthquake in 1994 and the Kobe earthquake in 1995 occurred, the concept of performance based design has been introduced for designing various kinds of important structures and buildings. Uniform hazard spectra (UHS), with annual exceedance probabilities, corresponding to the performance level of each structure, are required for performance-based design. The probabilistic seismic hazard analysis was performed using spectral ground motion prediction equations, which were developed from both Korean Peninsula and Central and Eastern US region, and several seismotectonic models suggested by 10 expert panel members in seismology and tectonics. The uniform hazard spectra for 5 highly populated cities in Korea, with recurrence period of 500, 1,000, and 2,500 years using the seismic hazard at the frequencies of 0.5, 1.0, 2.0, 5.0, 10.0 Hz and Peak ground acceleration (PGA) were analyzed using the probabilistic seismic hazard analysis. The sensitivity analysis suggests that spectral ground motion prediction equations impact much more on seismic hazard than what seismotectonic models do. The uniform hazard spectra commonly showed a maximum hazard at the frequency of 10 Hz and also showed the similar shape characteristics to the previous study and related technical guides to nuclear facilities.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.4
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• pp.329-340
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• 2006

Statement of problem: Damping of the peak force transmitted to implants has been reported by in vitro studies using impact forces on resin-veneered superstructures. Theoretical assumptions suggest that use of acrylic resin for the occlusal surfaces of a prosthesis would protect the connection between implant and bone. Therefore, the relationship between prosthesis materials and the force transmitted through the implant system also needs to be investigated under conditions that resemble the intraoral mechanical environment. Purpose: The purpose of this study was to analyze the fracture strength and modes of temporary prosthesis when a flange or occlusally extended structure were connected on the top of the abutment. Material and method: Modified abutments of winged and bulk design were made by casting the desired wax pattern which is made on the UCLA type plastic cylinder. Temporary crowns were made using templates on the modified abutments, and its fracture toughness and strain were compared to the traditional temporary prosthesis. To evaluate the effect of aging, 5.000 times of thermocycling were performed, and their result was compared to the 24hours specimen result. Results: The following conclusions were drawn from this study: 1. In the fracture toughness test, temporary crown's fracture line located next to the screw hole while modified designs with metal support showed fracture line on the metal and its propagation along the metal-resin interface. 2. Wing and bulk structure didn't show significant difference in the fracture toughness (p>0.05), but wing structure showed stress concentration on the screw hole area compared to bulk structure which showed even stress distribution. 3. In the fracture toughness test after thermocycling, wing and bulk structure showed increased or similar results in metal supported area while off-metal area and temporary crown showed decreased results. 4. In the strain measurement after thermocycling, its value increased in the temporary and bulk structure. However, wing structure showed decreased value in the loading point while increased value in the screw hole area. Conclusion: Wing type design showed compatible result to the bulk type that its application with composite resin prosthesis to the implant dentistry is considered promising.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.18-31
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• 2018

Rotorcrafts have more severe crashworthiness conditions than fixed wing aircraft owing to VTOL and hovering. Recently, with the increasing demand for highly efficient transportation system, application of composite materials to aircraft structures is increasing. However, due to the characteristics of composite materials that are susceptible to impact and crash, demand to prove the crashworthiness of composite structures is also increasing. The purpose of present study is to derive the structural concept of composite subfloor for rotorcrafts and verify it. In order to design a crashworthy composite subfloor, the conceptual design of the testbed helicopter for the demonstration and the derivation of energy absorbing requirement were carried out, and the composite energy absorber was designed and verified. Finally, the testbed for the demonstration of a crashworthy composite structure was fabricated, and performed free drop test. It was confirmed that the test results meet the criteria for ensuring occupant survivability.

• Therapeutic Science for Rehabilitation
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• v.7 no.4
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• pp.67-77
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• 2018

Objective: The purpose of this study was to examine the effects of an occupational therapy intervention program of arts and crafts on the activities of daily living and quality of life of outpatients after a stroke. Methods: Using an experimental pretest-posttest control group design, we conducted the following with ten participants diagnosed with stroke: one retest session, 10 intervention sessions, and one posttest session. MMSE-K (Korean version of the Mini-mental State Examination), COPM (Canadian Occupational Performance Measure), and WHOQOL-BREF (The World Health Organization Quality of Life-BREF) scores were obtained before and after the intervention. The results were analyzed using descriptive and nonparametric statistics. Results: As a result of comparing the pretest-posttest scores of the experimental and control groups, there was no significant difference in K-MBI score improvement in terms of activities of daily living. There was a significant difference in COPM scores between the experimental and control groups. There was a significant difference between the WHOQUP-BREF scores of the experimental group before and after the experiment, as well as between the groups. Conclusions: The results suggest that an arts and craft group occupational therapy intervention program for stroke patients may have a positive impact on activities of daily living and quality of life. Although an arts and craft group occupational therapy intervention program appears to be a promising approach, further studies are required to confirm these findings.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.111-121
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• 2001

Rockfall protection fences are used for diminishing rockfall damage in roads side slopes. In order to install the fences in effective way, the conditions of rock slopes and total predicted impact energy of fa11ing rock should be considered. However, the fences have been constructed without any consideration for lithology, height and slope angle of rock slope in Korea. In addition, the information about the performance of the protection fences, which should be evaluated by in-situ test or laboratory test in order to check out the practical use in the field, is not available. Therefore, in design manual for the rockfall protection fence, the specific details for the installation of this type of fence are not provided yet. The full sized rockfall in situ test was carried out for the calculation of falling energy of rock and the evaluation of the maximum energy absorbing capacity of fence. For this test, the rock slopes whose heights are about 20 m and dip angle of 65 degree, have been chosen. This is because those geometries are mean height and slope angle of most road cut slopes along Korean national highway. Based on the preliminary simulation procedure, four different sizes of concrete ball (0.7, 1.3, 2.3 and 4.3 ton) were prepared and flour different types of protection fence were constructed. The results of this test provide information about the maximum energy absorbing capacity of the fence, kinetic energy of rockfall and restitution coefficient, and these results can be utilized in the establishment of rockfall fence design and construction manual.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.155-175
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• 2005

Soil and rock dynamic properties such as shear wave velocity (VS), compressional wave velocity (VP) and corresponding Poisson's ratio ( v ) are very important geotechnical parameters in predicting deformational behavior of structures as well as practicing seismic design and performance evaluation. In an effort to measure the parameter efficiently and accurately, various bore-hole seismic testing techniques have been, thus, developed and used during past several decades. In this study, cross-hole seismic testing technique which is known as the most reliable seismic method was adopted for obtaining geotechnical dynamic properties. To perform successfully the cross-hole test for rock as well as soil layers regardless of the ground water level, spring-loaded source which impact laterally a subsurface ground in vertical bore-hole was developed and applied at three study areas, which contain four sites composed of two existing port sites and two new LNG storage facility sites. The geotechnical dynamic properties such as VS, VP and v with depth were efficiently determined from the laterally impacted cross-hole seismic tests at study sites, and were provided as the fundamental parameters for the seismic performance evaluation of the existing ports and the seismic design of the LNG storage facilities.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.161-172
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• 2017

To evaluate radiological impact from the operation of a low- and intermediate-level radioactive waste disposal facility, a logical presentation and explanation of expected accidental scenarios is essential to the stakeholders of the disposal facility. The logical assessment platform and procedure, including analysis of the safety function of disposal components, operational hazard analysis, operational risk analysis, and preparedness of remedial measures for operational safety, are improved in this study. In the operational risk analysis, both design measures and management measures are suggested to make it possible to connect among design, operation, and safety assessment within the same assessment platform. For the preparedness of logical assessment procedure, classification logic of an operational accident is suggested based on the probability of occurrence and consequences of assessment results. The improved assessment platform and procedure are applied to an operational accident analysis of the Korean low- and intermediate-level radioactive waste disposal facility and partly presented in this paper.

• Archives of design research
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• v.19 no.5 s.67
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• pp.373-382
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• 2006

In this study, emotional word logging software,'VideoTAME' was developed as an effective measurement tool for complementing the current psychological measuring methods. With the software, we measured the user's emotional changes while they interact with a product. The main goal of this study is to reveal the influence of usability on human emotions by analyzing the user's emotional changes while using a product. In this research, we asked 30 subjects to examine their emotional changes with watching the video clip recorded when they performed a series of tasks with a cellular phone in the experiment room. The results of this research indicated that negative emotion such as 'Uncomfortalbeness' was elicited mostly while they performed tasks which were difficult due to usability problems. On the other hand, positive emotion such as 'Satisfaction in Usability' was elicited for tasks which were easy to perform because of good usability. The reason for the user's emotional changes while they interact with a product can be assumed that the emotional changes were caused by specific situations they face when performing a task rather than the characteristics of task itself. We expect to clarify how usability of a product impact user's emotions in depth with more data collected and analyzed with the help of 'VideTAME'.