• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.697-700
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• 2020

We report the synthesis and characterization of quartz nanocrystals (NCs). Quartz NCs were synthesized from the dissolution of amorphous silica nanoparticle precursors under the mild hydrothermal condition of ~250 ℃ and autogenic pressure. It was confirmed that the average size of the nanostructure with a highly crystalline phase of α-quartz can be tuned in a relatively narrow range from 407.5 to 826.2 nm with respect to the reaction time. α-Quartz NCs have potential uses for technological applications in optoelectronics, sensing, and rechargeable battery devices.

• Journal of agricultural medicine and community health
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• v.29 no.2
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• pp.287-301
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• 2004

Objectives: The development of internet programs for smoking cessation was motivated to quit smoking in the large group of smokers. This personalized program consisted of tailored message to consider the smokers characteristics, and contain the informations on the outcomes of smoking cessation and the skills to be used in the quit attempts. The purpose of this study was to develop the internet management program and information push-delivery system for smoking cessation to encourage the personal intention to quit smoking. Methods: We conducted in 3 steps as developing push service to encourage intention of smoking cessation, analyzing problems of smoking cessation program through the pilot test and suggesting improvements by implication stages. Results: This program is delivered for 30 days. if the participants do not fail to quit smoking. The contents consisted of 13 stages which were divided on starting period. practical period, maintenance period and success period. And push service afforded the tailored message to participants using their e-mail. According to the evaluation of pilot test, the problems of internet information push-delivery service for smoking cessation were the over-tasks per visiting time, recording style of participants, difficulty of terms and sentences, lack of visual effects, absence of follow-up module and unsuitable link with main homepage. Improvements were divided on 3 stages by implication period. The first stage included the immediate improvements as improving link with homepage, modifying menu of smoking information and upload file of notice part. The second stage included the short term improvements as alleviating condition of withdrawal, coordinating start stage of retrial, modifying errors of information push-delivery service and addition of educational materials. The third stage included the long term improvements as development of follow-up module, cost-effectiveness evaluation, reducing contents quantity, introduction of checking style, compensation of graphics effect and review for SMS utilization. Conclusions: This program contribute to improving smoking cessation rate. Therefore this program should be tested in a community to evaluate the effectiveness. To promote the effectiveness, this program should be developed the contents and the strategies for various targets, and established the follow-up system for ex-smokers.

• Tunnel and Underground Space
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• v.28 no.3
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• pp.258-276
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• 2018

The accurate and quantitative ground information on the hydraulic conductivity characteristics of rock mass is one of the key factors for evaluation of the hydro-geological behaviour of rock mass around an excavated opening under high water pressure. For tunnel and rock structures in seabed, where the sea acts as an infinite source of water, its importance become greater with increasing construction depth below sea level. In this study, to improve the problems related with poor system configuration and incorrect data acquisition of previous hydraulic packer testing equipment, we newly developed an integrated main frame and 30 bar level waterproof downhole sonde apparatus, which were optimized for deep hydraulic packer test in seabed rock mass. Integration of individual test equipment into one frame allows safe and efficient field testing work on a narrow offshore drilling platform. For the integrated type main frame, it is possible to make precise stepwise control of downhole net injection pressure at intervals of $2.0kg_f/cm^2$ or less with dual hydraulic oil volume controller. To ensure the system performance and the operational stability of the prototype mainframe and downhole sonde apparatus, the field feasibility tests were completed in two research boreholes, and using the developed apparatus, the REV(Representative Elementary Volume) scale deep hydraulic packer tests were successfully carried out at a borehole located in the basalt region, Jeju. In this paper, the characteristics of the new testing apparatus are briefly introduced and also some results from the laboratory and in-situ performance tests are shown.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.371-376
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• 2014

The process of flip-chip bump bonding, Au wire bonding and encapsulation were sucessfully developed and modularized. The CdTe sensor and ROIC were optimally jointed together at $150^{\circ}C$ and $270^{\circ}C$ respectively under24.5 N for 30s. To make SnAg bump on ROIC easy to be bonded, the higher bonding temperature was established than CdTe sensor's. In addition, the bonding pressure was lowered minimally because CdTe Sensor is easier to break than Si Sensor. CdTe multi-energy sensor module observed were no electrical failures in the joints using developed flip chip bump bonding and Au wire bonding process. As a result of measurement, shearing force was $2.45kgf/mm^2$ and, it is enough bonding force against threshold force, $2kgf/mm^2s$.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.575-593
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• 2012

This paper briefly introduces the scope and objectives of SKB Task 8, which is an international cooperative research project. In addition, the hydraulic behaviors of bentonite buffer focusing on the interactions between bentonite and a rock mass with a joint were investigated using TOUGH2 code as part of a sub-mission of Task 8a. The effects of a rock joint and high capillary pressure of bentonite on the re-saturation properties and pressure distribution in a buffer were identified and successfully incorporated in the TOUGH2 code. Based on the numerical results, it was found that the speed of re-saturation in bentonite surrounded by a rock mass with a joint is 2.5 to 12 times faster than that in a condition without a rock joint, while the degree of saturation in the lower part of the buffer material is generally higher than in the upper part in both the cases of with and without a joint. It can be anticipated that the results obtained from this study can be applied to an estimation of the full saturation time and a determination of optimum thickness with regard to the design of the bentonite buffer in a high level waste disposal system.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.32-39
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• 2005

When PFC(Perfluorocarbonate) decontamination technology is applied to removal of radioactive contaminated particulate adhered at surface during the operation of nuclear research facilities, it is necessary to develop a filtration equipment to reuse of PFC solution due to high price, also to minimize the volume of second wastewater. Contaminated characteristics of hot particulate was investigated and a filtration process was presented to remove suspended radioactive particulate from PFC decontamination wastewater generated on PFC decontamination. The range of size of hot particulate adhered at the surface of research facilities measured by SEM was $0.1{\sim}10{\mu}m$. Hot particulate of more than $2{\mu}m$ in PFC contamination wastewater was removed by first filter and then hot particulate of more than $0.2{\mu}m$ was removed by second filter. Results of filter experiments showed that filtration efficiency of PVDF(Poly vinylidene fluoride), PP(Polypropylene), Ceramic filter was $95{\sim}97\%$. A ceramic filter showed a higher filtration efficiency with a little low permeate volume. Also, a ceramic of inorganic compound could be broken easily on experiment and has a high price but was highly stable at radioactivity in comparison of PVDF and PP of a macromolecule which generate $H_2$ gas in alpha radioactivity environment.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.941-948
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• 2022

Disaster response robots are deployed to disaster sites where human access is difficult and dangerous. The disaster response robots explore the disaster sites prevent a structural collapse and perform lifesaving to minimize damage. It is difficult to operate robots in the disaster sites due to rough terrains where various obstacles are scattered, communication failures and invisible environments. In this paper, we developed a series connectable wheeled robot module. The series connectable wheeled robot module was developed into two types: an active driven robot module and a passive driven robot module. A wheeled robot was built by connecting the two active type robot modules and one passive type robot module. Two robot modules were connected by one DoF rotating joint, allowing the wheeled robot to avoid obstructions in a vertical direction. The wheeled robot performed driving and obstacle avoidance using only pressure sensors, which allows the wheeled robot operate in the invisible environment. An obstacle avoidance experiment was conducted to evaluate the performance of the wheeled robot consisting of two active driven wheeled robot modules and one passive driven wheeled robot module. The wheeled robot successfully avoided step-shaped obstacles with a maximum height of 80 mm in a time of 24.5 seconds using only a pressure sensors, which confirms that the wheeled robot possible to perform the driving and the obstacle avoidance in invisible environment.

• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.23-32
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• 1988

Finger injuries are becoming more common with the increasing use of mechanical industrial and household appliances. Among the hand injuries, amputation is the serious disaster to the patient. Recently, application of microsurgical technique to the reattachment of ampuatated digits has been common clinical procedures. We performed microsurgical replantation to the 75 patients with 102 digits from march in 1986 to february in 1988. The following results were obtained. 1. The most common age distribution was third decade and male to female ratio was about 5:1. 2. The ratio of right to left hand was about 1:1 but the dominant to non-dominant hand was about 2:1. 3. The index finger was most commonly injured and the next was middle finger. 4. The most common type of the injuries was the crushing injury and the most common vector was a kind of pressor. 5. The anesthesia was performed in equal ratio between the general and regional anesthesia. 6. The survival rate of microreplantation to the injuries of the zone II was 77.8% and zone III was 80%. 7. The functional result after replantation at zone II was better than zone III. 8. Microreplantation was performed in any case of the type of the injury, the severity of crushing and the ischemic time, and the patients requirement was an important factor.

• Journal of Family Resource Management and Policy Review
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• v.27 no.4
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• pp.1-17
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• 2023

This study examines the entrepreneurial experiences of unmarried mothers living in a community who have succeeded in starting a business. Attention was given to the maternal and labor rights of five single mothers in a community who gave birth, raised children, and engaged in vocational activities. Data were collected through one-on-one in-depth discussions with the participants and analyzed using Colaizzi's descriptive-phenomenological method. The data analysis revealed 53 themes and 10 clusters of themes. Based on these results, items such as overcoming pregnancy conflict, reasons for starting a business, and successful entrepreneurial experience were identified and described. The key themes of this study include "Pressure to live", "Hold oneself responsible for an unblessed life", "Stigma and deprivation of opportunity", "Maintaining basic life amid anxiety", "Starting from ground zero", "Work and parenting tug-of-war", "Let's rely on my ability rather than external support", "Securing credit capital", "Philosophy for shared growth" and "Infinite possibilities at the edge of a cliff". In the attempt to start a business using positive psychological capital for the well-being of themselves and their children's, the mothers uncovered social capital, which led to mutual growth. Based on the research results, the ethics and resilience of shared growth were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1838-1843
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• 2014

Nanoimprint lithography (NIL) fabrication process is regarded as the main alternative to existing expensive photo-lithography in areas such as micro- and nano-electronics including optical components and sensors, as well as the solar cell and display device industries. Functional patterns, including anti-reflective moth-eye pattern, photonic crystal pattern, fabricated by NIL can improve the overall efficiency of such devices. To successfully imprint a nano-sized pattern, the process conditions such as temperature, pressure, and time should be appropriately selected. In this paper, a cavity-filling process of the moth-eye pattern during the thermal-NIL within the temperature range, where the polymer resist shows the viscoelastic behaviors with consideration of stress relaxation effect of the polymer, were investigated with three-dimensional finite element analysis. The effects of initial thickness of polymer resist and imprinting pressure on cavity-filling process has been discussed. From the analysis results it was found that the cavity filling can be completed within 100 s, under the pressure of more than 4 MPa.