• KSBB Journal
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• v.18 no.6
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• pp.448-454
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• 2003

We studied on the removal of toluene vapors in a lab-scale biofilter. There are three biofilters packed with reticulated polyurethane foams of different porosities of 15, 25, 45 PPI (Pore Per Inch) as media. A toluene-degrading strain (Pseudomonas Putida KCCM 11348, ATCC 12633) was naturally immobilized on the filter media by circulating the culture media. Three biofilters were operated under different sets of continuous experiments, varying both the design and operation parameters such as the inlet toluene concentration and the flow rate. Maximum elimination capacity of 115.5g/㎥hr of biofilter packed with foams of 25 PPI was obtained for toluene degradation. The effect of operating conditions such as flow rate, inlet toluene concentration and porosity on the performance of the biofilter was investigated.

• Smart Structures and Systems
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• v.16 no.3
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• pp.383-399
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• 2015

Today, as railways increase their capacity and speeds, it is more important than ever to be completely aware of the state of vehicles fleet's condition to ensure the highest quality and safety standards, as well as being able to maintain the costs as low as possible. Operation of a modern, dynamic and efficient railway demands a real time, accurate and reliable evaluation of the infrastructure assets, including signal networks and diagnostic systems able to acquire functional parameters. In the conventional system, measurement data are reliably collected using coaxial wires for communication between sensors and the repository. As sensors grow in size, the cost of the monitoring system can grow. Recently, auto-powered wireless sensor has been considered as an alternative tool for economical and accurate realization of structural health monitoring system, being provided by the following essential features: on-board micro-processor, sensing capability, wireless communication, auto-powered battery, and low cost. In this work, an original harvester device is designed to supply wireless sensor system battery using train bogie energy. Piezoelectric materials have in here considered due to their established ability to directly convert applied strain energy into usable electric energy and their relatively simple modelling into an integrated system. The mechanical and electrical properties of the system are studied according to the project specifications. The numerical formulation is implemented with in-house code using commercial software tool and then experimentally validated through a proof of concept setup using an excitation signal by a real application scenario.

• Physical Therapy Rehabilitation Science
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• v.6 no.2
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• pp.71-76
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• 2017

Objective: The purpose of this study was to investigate the musculoskeletal diseases (MSDs) that occur in heavy industrial workers according to the occupational category, prevalence, environment, and number of physical therapy visits. Design: Retrospective cohort study. Methods: For this study, data was collected of workers who were engaged in heavy industry in Korea and who visited the company physicians and received physical therapy in 2016. Data was collected from 855 subjects and was analyzed. With the data collected, analysis of the type and prevalence of MSDs and the number of physical therapy visits that have occurred according to the occupational category and environment was performed. Results: The most common MSDs were lumbar sprains and spasms (31.1%), and shoulder sprain and spasm (19.4%). In addition, the most common type of MSDs according to the occupational category and environment (occupational type) were lumbar sprain and spasms in 11 occupations, including white collar workers, and in milling, inspection, crane operation, and finishing jobs, shoulder muscle sprain and strain were the most common disorders. Also, the prevalence of MSDs according to occupational category and environment (occupational type) was the highest in workers involved with welding, which was 29.7%. Conclusions: Through this study, the type and prevalence of MSDs according to the occupational category and environment of heavy industrial workers have been confirmed. Further studies are necessary to study the future types of the work patterns of industrial workers and to develop a system for preventing and managing MSDs that may occur.

• Journal of Family Resource Management and Policy Review
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• v.5 no.1
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• pp.61-78
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• 2001

This study intends to provide the groundwork for an establishment of women entrepreneur policy and the guidelines for start-up of women-owned business. The findings of the study are as follows; Women starts business for a financial reasons and this makes up 26 percent, which ranked the highest of respondents motive for starting up a business. The double labor - due 새 the practice of housework and running a business simultaneously - forms 19.6 percent of the bottleneck in operating business. In addition, the worst financial strain, 43 percent, occurred during the business preparatory period. As the entrepreneurship is higher, they are more backed up with support in education and training. In addition, annual net profit of business operated by the older age group is relatively greater. The firm performance is greater as she holds a higher academic degree. As the goal of annual net profit is higher that is set up before the start-up, the net gain turns out to be greater in actual operation, thus resulting in greater effects. The study shows that when they received economic aid, the initial capital had been greatly affected The younger age group makes up the higher percentage of support in education and training. After considering all the findings collectively, the conclusions are as follows; First, the firm performance is affected by the entrepreneurship, schooling, age, and the goal of the female entrepreneur. Second, a support in education and economic does not have a direct effect on the firm performance. However, the study reveals that the entrepreneurship of those who received educational support is higher than that of those who did not. Third, the in-depth interview reveals the facts that how they had been brought up and how the role of the family had a significant effect on their management of business.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.2
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• pp.120-130
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• 1999

This investigation studied the effect of ovariectomy on the temporomandibular joint (TMJ) of rat. Forty female Sprauge-Dawley strain white rats, each weighing about 200grams were used and divided into two groups. The one group was performed ovariectomy, and the other was performed sham operation. Both group were killed at the intervals of 3 days, 1, 2, 4, and 8 weeks postoperatively, paraffin section were stained with H&E, MT and histomorphometric study of the TMJ was performed in a synchronous manner with an sham operated control group The result were as follows: 1. At 4 weeks after ovariectomy, an adhesion between the inferior surface of the articular disc and the condyle was observed in the central portion. At 8 weeks after ovariectomy, a focal thickening of the bone (osteophyte) was observed in anterior portion and there was a marked decrease in the trabecular bone in the posterior region. 2. The thickness of cartilage zone was increased at 2 weeks postopratively in the central portion, and decreased at 4 weeks postopratively in the posterior portion. The thickness of transitional zone was decreased at 1 week postoperatively in the anterior and proliferating zone was decreased postoperatively. The thickness of articular zone was decreased at 3 days postopratively in the anterior portion, and decreased at 1 week postoperatively in the central portion. From the above finding, we could conclue that estrogen deficiency in rats causes alteration of TMJ in marked early stage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.2
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• pp.18-25
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• 2016

Bascule bridge, with its use to help vessels ply, has a several examples overseas of being serviced for more than decades years by careful maintenance, admitted its significance as landmarks for its rareness. Yeongdo Bridge, the sole bascule bridge in Korea was reconstructed in 2013 after being demolished because of its corrosion and aging, and now operates once in a day. Recently, safety inspections are executed thanks to demands getting higher for maintenance and safety of bridges, but measurement and analysis about bascule bridges are scarce. This study includes the analysis of the bascule bridge's behavior such as stress, vibration and reaction in normal condition and while it lifts up, based on measurement. We expect that this study will be used as an initial data to compare and confirm bridge's changes as service year and the number of operation increase.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.72-77
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• 2014

It is known that there is no demand for building the arctic environment in Korea. However, it is important to use the different energy source instead of fuel source due to global warming. It is now demanded of using gas of Alaska and Siberia for long term developing the natural gas. The design of gas pipelines in Korea is very different from the arctic region. The operation of gas in arctic region have to consider of arctic region such as permafrost and active regions. It is needed to understand of gas pipeline design with different arctic soil properties. Nowadays, the pipelines is designed with stress-based and but there is demanded for strain based design with more deformed pipeline. We study of arctic environment with different active region using Finite Element Method of thermal elasto-plastic analysis.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.77-87
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• 1994

This paper deals with an automated forming sequence design system by which designers can determine desirable operation sequences even if they have little experience in the design of cold forging process. The forming sequence design in the cold forging is very important and requires many kinds of technical and empirical knowledge. They system isproposed, which generates forming sequence plans for the multistage cold forging of axisymmtrical solid products. Since the process of metal forming can be considered as a transformation of geometry, treatment of the geometry of the product is a key in planning process. To recognize the geometry of the product section, section entity representation and primitive geometries were used. Section entity representation can be used for the calculation of maximum diameter, maximum height, and volume. Forming sequence for the part can be determined by means of primitive geometries such as cylinder, cone, convex, and concave. By utilizing this geometrical characteristics (diameter, height, and radius), the product geometry is expressed by a list of the priitive geometries. Accordingly the forming sequence design is formulated as the search problem which starts with a billet geometry and finishes with a given product one. Using the developed system, the sequence drawing with all dimensions, which includes the proper sequence of operations for the part, is generated under the environment of AutoCAD. Based on the results of forming sequence, process variables(strain, punch pressure, die inner pressure, and forming load) are determined.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.749-765
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• 2010

There are on-going efforts to utilize guided waves for structural damage detection. Active sensing devices such as lead zirconate titanate (PZT) have been widely used for guided wave generation and sensing. In addition, there has been increasing interest in adopting wireless sensing to structural health monitoring (SHM) applications. One of major challenges in wireless SHM is to secure power necessary to operate the wireless sensors. However, because active sensing devices demand relatively high electric power compared to conventional passive sensors such as accelerometers and strain gauges, existing battery technologies may not be suitable for long-term operation of the active sensing devices. To tackle this problem, a new wireless power transmission paradigm has been developed in this study. The proposed technique wirelessly transmits power necessary for PZT-based guided wave generation using laser and optoelectronic devices. First, a desired waveform is generated and the intensity of the laser source is modulated accordingly using an electro-optic modulator (EOM). Next, the modulated laser is wirelessly transmitted to a photodiode connected to a PZT. Then, the photodiode converts the transmitted light into an electric signal and excites the PZT to generate guided waves on the structure where the PZT is attached to. Finally, the corresponding response from the sensing PZT is measured. The feasibility of the proposed method for wireless guided wave generation has been experimentally demonstrated.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.4
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• pp.335-342
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• 2019

The objective of this study is to analyze the mechanical properties of plywood used as a thermal insulating material for LNG CCS (Liquefied Natural Gas, Cargo Containment System). It is created by bonding an odd number of parallel and perpendicular direction for preventing contraction and expansion of wood. Also plywood is widely used as LNG CCS insulating material because of its durability, light weight and high stiffness. Since LNG CCS is loaded with liquid cargo, the impact load by sloshing during operation and the wide temperature range (room temperature, low temperature, cryogenic temperature) exposed during loading, unloading should be considered. The thickness of the plywood which is used for the membrane type MARKIII was selected as the thickness of the test specimen. In this present study, plywood is analyzed by the fracture behavior and mechanical properties of plywood by temperature and grain direction. In addition, it is necessary to analyze the fracture shape and predict the fracture strain by using regression model because the critical load may cause cracks inside the tank, which may affect the leakage of cryogenic liquid.