• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.10a
• /
• pp.601-612
• /
• 2005

In mountainous area, Two parallel tunnels have been usually recognized as a road tunnel which has benefits in aspects of cost and stability. However, Design and construction of 2-Arch road tunnel are growing recently due to environmental destruction, compensation of land and difficulty of route separation. As studies are mainly undergoing on only guaranteeing stability and developing a waterproofing-drainage system to avoid water leakage through comprehension for characteristics of 2-arch tunnel behaviors, there is a tendency to evaluate quantity of support by empirical method with a tunnel which has a complicated cross-section and lack of construction ability. In this study, therefore, we made a plan of tunnel cross-section which had shown good construction ability and developed the waterproofing-drainage system which is able to solve the water leakage problem fundamentally by analyzing precedented 2-arch tunnels and investigating their sites in and out of nation. We also determined fixed quantity of support by a large-scale model test and numerical analysis. We want to contribute to 2-arch tunnel design hereafter introducing design procedure and method applied here.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.24 no.3
• /
• pp.5-13
• /
• 1996

This study is about to prove one factor among many ones that contribute to the formation of the Japanese Garden's pattren. It is believed by this study that distinguished Japanese Garden's pattren are made possible by an organized ability of the japaneses traditional landscape artists who had ability to develope a diversified forms of applications within the organized framework. To verify this assumption, the study has chosen Ryu Gen In, temple garden that is considered to determine the pattren of Japanese Garden best with a new concept ; Organization. The results of this analysis show as follows : 1. Ryu Gen In, consists of a series of building and five-small gardens, is largely organized by the union of two geometric formations : concave and convex. Each garden as a sub-organization is further organixed with a series of tree-branch typed structure. 2. The five-small gardens are formed jinto a whole system by connecting each one with floor. This connection makes a timely organization. 3. Each small garden is further organized alloted roles, namely, depends upon whether they play a major or minor role. 4. It is believed that sands and moss play a cotrolling role to conbine the elements into one within each unit of small garden. 5. It is found that figured sands, moss, sands and moss, or shrubs are used as means of organization to connect the small group elements within each small gardens. 6. It is considered that buildings and mud-walls are used as means of separation between Ryu Gen In and an outer world, and betwen small gardens.

• Proceedings of the Korea Crystallographic Association Conference
• /
• 2002.11a
• /
• pp.54-55
• /
• 2002

The fabrication, characterization and manipulation of nanoparticle system brings together physics, chemistry, materials science and biology in an unprecedented way. Phenomena occurring in such systems are fundamental to the workings of electronic devices, but also to living organisms. The ability to fabricate the surface of nanoparticles Is essential in the further development of functional devices that incorporate nanoscale features. Even more essential is the ability to introduce a wide range of chemical and materials flexibility into these structures to build up more complex nanostructures that can ultimately rival biological nanosystems. In this respect, polymers are potentially ideal nanoscale building blocks because of their length scale, well-defined architecture, controlled synthesis, ease of processing and wide range of chemical functionality that can be incorporated. In this presentation, we will look at a number of promising polymer-based nanoparticle fabrication strategies that have been developed recently, with an emphasis on those techniques that incorporate nanostructured polymeric particles into electronic devices or biomedical applications. And functional nanoparticles deliberately designed using several powerful process methods and their application will be discussed. Nanostructured nanoparticles, what we called, implies dispersed colloids with the size ranged from several nanometers to hundreds of nanometer. They have extremely large surface area, thus it is very important to control the morphology or surface functionality fitted for adequate objectives and properties. Their properties should be controlled for various kind of bio-related technologies, such as immunomagnetic cell separation, drug delivery systems, labeling and identification of lymphocyte populations, extracorporeal and hemoperfusion systems, etc. Well-defined polymeric nanoparticles can be considered as smart bomb or MEMS.

• Journal of Environmental Health Sciences
• /
• v.41 no.5
• /
• pp.327-334
• /
• 2015

Objectives: In order to review both the effects of sewage sludge dewaterability and deodorizing ability in the existing advanced sewage treatment process, BIO-CLOD (a solidified mixture of 10% Bacillus concentrate and inorganics) was used as an inorganic conditioner effective for deodorization treatment in addition to the removal of organic matter and nutritive salts. Methods: Sludge dewaterability was evaluated using specific resistance to filtration (SRF) experiments with six agitators and two types of commercially available BIO-CLOD; one that is made by grinding solid matter (powdered BIO-CLOD) and one that has been obtained by sieving a separation with a particle diameter of 100 mesh (100 mesh BIO-CLOD). For deodorization odor treatment experiments, 20 g of commercially available solid BIO-CLOD was submerged in four liters of sewage sludge and mixed and agitated for 45 days. Results: When BIO-CLOD was injected into sewage sludge to experimentally compare specific resistance to filtration (SRF), the optimum amount of BIO-CLOD to be injected was shown to be 2% w/v and the SRF value in this case was $1.35{\times}10^{12}m/kg$. pH changes following BIO-CLOD injection were within 6.5-7.0. By 14 days after submerging BIO-CLOD into the sewage sludge to evaluate its deodorizing ability, $H_2S$ decreased by 68% and methyl mercaptan decreased by 74%. By 45 days after the submergal, both items decreased by 100%, indicating deodorizing ability. Conclusion: To compare the levels of dewaterablity of sewage sludge at different particle sizes of inorganic conditioner, powdered BIO-CLOD, particle size 100 mesh BIO-CLOD, and bentonite were tested. It could be seen that as the powdered BIO-CLOD increased, the precipitability increased up to 62% in 30 minutes. As an inorganic conditioner, BIO-CLOD was identified as a stable sludge conditioner that does not affect pH.

• Journal of dental hygiene science
• /
• v.20 no.3
• /
• pp.163-170
• /
• 2020

Background: Job satisfaction of dental hygienists has been discussed continuously in dental hygiene research. It has been the most representative performance variable in dental and human resource management. However, in quantitative research, most of the studies have analyzed the causal relationship with variables related to dental hygienists' job satisfaction. The existing qualitative research contains only the studies that targeted dental hygienists with an experience of more than 10 years. The present study aimed to understand and to characterize the job satisfaction of dental hygienists with an experience of 2 to 10 years and to compare it with the qualitative research on dental hygienists with an experience of 10 or more years. Methods: An in-depth interview of dental hygienists with 2 to 10 years of experience working in 10 dental clinics was conducted. For data analysis, Giorgi's analysis method was used. Results: After analyzing the meaning of job satisfaction of dental hygienists, 180 semantic words and 19 subcategories were derived. The results of the interview were categorized into for central meanings: recognition and rewards, work experience and ability improvement, occupational characteristics, and work characteristics. Recognition and rewards included workplace recognition, patient recognition, self-effort and recognition, and the feeling of being rewarded. Work experience and ability improvement included various work experiences and factors relates to improving the work ability. Occupational characteristics included professional job, interest and persistence, job extensibility, and no burden of employment. Work characteristics included working conditions and separation of work and private life. Conclusion: The development of tools to measure the level of dental hygienists' job satisfaction after long-term service and to conduct follow-up research regarding ways and effects to improve job satisfaction is needed.

• The Journal of Korean Institute for Practical Engineering Education
• /
• v.2 no.1
• /
• pp.28-34
• /
• 2010

Traditionally engineers' main roles are concentrated on solving any given problems and engineering education has emphasized problem solving ability. Therefore engineers intend to solve easily perceived problems with their knowledge and experience instead of trying to analyze the given problems thoroughly and to define real problems, and go through lots of trial and error. So, engineers require the ability to define real problems accurately before trying to solve the problems. This study proposes a real problem definition process using visualization of a core zone and TRIZ concepts such as contradictions and IFR(Ideal Final Result) in order to define real problems with minimum trial and error. TRIZ is the theory of inventive problem solving and was developed by a Soviet engineer and researcher Genrich Altshuller from 1946. Nowadays many industries use TRIZ and its effectiveness was already proved by lots of real problem solving in various areas. Therefore TRIZ might be very effective tool for developing students' inventive thinking ability in engineering education.

• Physical Therapy Korea
• /
• v.21 no.4
• /
• pp.56-66
• /
• 2014

For maintaining adequate psychometric properties when reducing the number of items from an instrument, item level psychometrics is crucial. Strategies such as low item correlation or factor loadings, using classical test theory, have traditionally been advocated. The purpose of this study is to describe the development of a new short form assessing the impact of low back pain on physical activity. Rasch measurement model has been applied to the International Classification of Functioning, Disability and Health Activity Measure (ICF-AM). One hundred and one individuals with low back pain aged 19-89 years (mean age: $48.1{\pm}17.3$) who live in the community were participated in the study. Twenty-seven items of lifting/carrying construct of the ICF-AM were analyzed. Ten items were selected from the construct to create a short form. Item elimination criteria include: 1) high or low mean square (out of the range: .6-1.4 for the fit statistics), 2) similar item calibrations to adjacent items, 3) person separation value, and item-person map for potential gap in person ability continuum. All 10 items of the short form fit to the Rasch model except one item (i.e., carrying toddler on back). Despite its high infit and outfit statistics (1.90/2.17), the item had to be reinstated due to potential gaps at the upper extreme of person ability level. The short form had a slightly better spread of person ability continuum compared to the entire set of item. The created short form separated individuals with low back pain into nearly 4 groups, while the entire set of items separated the individuals into 6 groups. The findings prompted multidimensional models for better explanation of the lifting/carrying domain. The item level psychometrics based on the Rasch model can be useful in developing short forms with rationally retained items.

• Clean Technology
• /
• v.10 no.2
• /
• pp.73-87
• /
• 2004

In most of industrial fields, cleaning is employed for removing soils on their products or parts. Halogenated cleaning agents such as CFC-113, 1,1,1-TCE(1,1,1-trichloroethane), MC(methylene chloride) and TCE (trichloroethylene) have been used as cleaning ones in most of companies in the world since their excellent performance of cleaning ability and good material compatibility. However, CFC-113 and 1,1,1-TCE which are ozone destruction substances are not used any more in the advanced countries because of the which are ozone destruction substances are not used any more in the advanced countries because of the Montreal protocol. MC and TCE are now used restrictively at small part of industrial fields in most of countries since they are known to be hazardous or carcinogenic materials. Thus, it is indispensible that the alternative cleaning agents which are environmental-friendly and safe, and show good cleaning ability should be developed or utilized for replacement of the halogenated cleaning agents. Aqueous/semi-aqueous cleaning agents are evaluated to be promising alternative ones among various alternatives in environmental and economical view point. In this study, commercially available 12 aqueous and 6 semi-aqueous cleaning agents were selected and their physical properties, cleaning abilities, rinsing abilities and recycling of contaminated rinse water were measured and analyzed. Aqueous cleaning agents with higher wetting index showed better cleaning ability compared with those with lower wetting index. However wetting index did not have any correlation with cleaning ability in semi-aqueous cleaning agents. It was observed that soil concentration in aqueous and semi-aqueous cleaning agents should be maintained below the certain concentrations which depend on types of clearing agents. More than 70% soils in contaminated rinse water by some of aqueous and semi-aqueous clearing agents could be separated by simple settling method. This means that some cleaning agents with high oil-water separation efficiency will be effiective for recycling oil-contaminated rinse water. It was found that contaminated rinse water with aqueous agents was purified easiy by ultrafiltration method with PAN membrane of 30 kDa.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.4
• /
• pp.679-688
• /
• 2000

Dispersants, which are used to break water-in-oil emulsions and to remediate oil-spills, are another water pollutants. In this study, magnetic separation technology was applied to remove dispersants from the sea. Magnetite and maghemite were used as magnetic sorbents and SDDBS, an anionic surfactant and Triton X-100, a nonionic surfactant, were employed as dispersants. Batch experiments were undertaken to study the sorption capacity and sorption equilibrium, and water-bath experiments were conducted to simulate the real situation and to describe the recovery of magnetic particles by the permanent magnet or electromagnet. Maghemite has rather constant removal efficiency for dispersants, regardless of surfactant species. On the other hand, removal efficiency by magnetite is higher for anionic surfactant than maghemite and is higher in distilled water than in seawater which contains more ions. The sorption of dispersants to magnetite is explained by electrostatic attraction and that of maghemite is described not only by electrostatic attraction, but also by structural characteristics that provide high sorption ability and surface condition. Water bath experimental results showed that recovery efficiency of magnetic particle after sorption for dispersants is nearly 100%. It is suggested that this magnetic separation technology is an effective way of dispersant removal because of short operating time, high sorption capacity, and high recovery efficiency of sorbents.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.2
• /
• pp.33-41
• /
• 2023

The application of seismic separation joints that can improve the deformation capacity of piping is an effective way to improve seismic performance. Seismic separation joints capable of axial expansion and bending deformation are installed where deformation is expected and used for the purpose of safely protecting the piping. Bellows are flexible and have low stiffness, so they can be used as seismic separation joints because they have excellent ability to respond to relatively large deformation. In this study, the seismic performance and limit state for bending deformation of 2-ply and 3-ply bellows specimens were evaluated. Seismic performance was evaluated by applying an increasing cyclic load to consider low-cycle fatigue due to seismic load. In order to confirm the margin for the limit state of the evaluated seismic performance, an experiment was conducted in which a cyclic loading of constant amplitude was applied. As a result of the experiment, it was confirmed that the bellows specimen was made of stainless steel and had a high elongation, so that the 2-ply bellows specimen had the limit performance of resisting within 3 cycles even at the maximum forced displacement of the 3-ply bellows specimen.