• Transactions of Materials Processing
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• v.13 no.5
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• pp.422-428
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• 2004

At present, the design of extrusion dies and operation in extrusion companies are primarily based on trial and error. The experience of the die designer, the press operator and the die corrector determine the performance of the extrusion die and the efficiency of the process. In order to produce defect-free products of desirable quality in terms of strength, surface quality and geometrical dimensions, it is important to obtain more knowledge of the processes that occur during extrusion. Recently, to reduce the costs of designing and manufacturing of extrusion dies, and to ensure the quality of the extruded products, numerical simulation for extrusion processes such as FEM (finite element method) is applied increasingly and becomes a very important tool for the design and development of new products. However, most of the studies about FE simulation have been accomplished for simple geometry and low extrusion ratio in the filed of steady metal flow conditions. The extruded products of AI alloy in industrial practice involve complicated sectional geometry. This study was designed to reduce the time of die design and manufacturing in the extrusion process using FEM simulation. FEM simulations of extrusion process were performed in non-steady states conditions by changing weld plate included in extrusion die set. Product which was employed in this study is heat sink that has been used in the parts of heat exchanger of electric circuits. It is generally applied for aluminum or its alloys due to heat efficiency and easy production of complicated shapes, and manufactured by extrusion process. The simulated results showed that weld plate shape in extrusion dies influences meta] flow and dimensional accuracy of products.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5551-5557
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• 2012

Sedimentary rocks dug up in construction fields are mostly stockpiled for landfill disposal, leading to an increase in construction costs and construction inefficiency. After screening, some of the sandstone can be used as aggregate; however, most of the shale ends up as industrial waste in practice. In this study, to stabilize the demand and develop resources for alternative aggregates of concrete, the potential use of shale, which is widely distributed in the Daegu-Kyeongbuk region, as a concrete aggregate was evaluated. Red and black shale exported from a Daegu excavation site was selected for use in the experiments and evaluated by comparing with hornfels, which is widely used as a coarse aggregate and is a type of andesite and metamorphosed sedimentary rock. The physical properties of the aggregate were evaluated in accordance with the test methods of KS F 2527 "crushed concrete aggregate," and the compressive strength against the shale aggregate replacement ratio was measured. The compressive strength of the concrete after 28 days was 30.8 MPa when the black shale replaced 100% of the aggregate in the concrete and 31.1 MPa when the red shale replaced 100% of the aggregate in the concrete. Compared with the compressive strength of 37.5 MPa for concrete prepared by using plain aggregate, using shale as a substitute for the aggregate produced an average compressive strength that was 82% of normal concrete.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.6857-6862
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• 2015

Background: To identify the optimal cost effective strategy for the management of women having ASC-US who attended at King Chulalongkorn Memorial Hospital (KMCH). Design: An Economical Analysis based on a retrospective study. Subject: The women who were referred to the gynecological department due to screening result of ASC-US at King Chulalongkorn Memorial Hospital, a general and tertiary referral center in Bangkok Thailand, from Jan 2008 - Dec 2012. Materials and Methods: A decision tree-based was constructed to evaluate the cost effectiveness of three follow up strategies in the management of ASC-US results: repeat cytology, triage with HPV testing and immediate colposcopy. Each ASC-US woman made the decision of each strategy after receiving all details about this algorithm, advantages and disadvantages of each strategy from a doctor. The model compared the incremental costs per case of high-grade cervical intraepithelial neoplasia (CIN2+) detected as measured by incremental cost-effectiveness ratio (ICER). Results: From the provider's perspective, immediate colposcopy is the least costly strategy and also the most effective option among the three follow up strategies. Compared with HPV triage, repeat cytology triage is less costly than HPV triage, whereas the latter provides a more effective option at an incremental cost-effectiveness ratio (ICER) of 56,048 Baht per additional case of CIN 2+ detected. From the patient's perspective, the least costly and least effective is repeat cytology triage. Repeat colposcopy has an incremental cost-effectiveness (ICER) of 2,500 Baht per additional case of CIN2+ detected when compared to colposcopy. From the sensitivity analysis, immediate colposcopy triage is no longer cost effective when the cost exceeds 2,250 Baht or the cost of cytology is less than 50 Baht (1USD = 31.58 THB). Conclusions: In women with ASC-US cytology, colposcopy is more cost-effective than repeat cytology or triage with HPV testing for both provider and patient perspectives.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.2
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• pp.109-116
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• 2014

In this study, the factors affecting the profitability of the oriental medicine hospitals of University to be analyzed. To do this, profitability indicators and current ratio, liquidity, turnover ratio, cost factors analysis and suggested ways to improve management. The results are as follows, the operating margin(1.17%). the return on assets(3.76%), the net profit to gross revenues(2.37%), and the net profit to total assets(-1.89) were lower than the average of the entire oriental medicine hospitals in Korea(respectively 8.9%, 8.7%, 2.6%, 2.5%). Current ratio(256.76%), quick ratio(231.17%), fixed ratio(121.02%), and total assets turnover(135.69%) were similar to the average of all oriental medicine hospitals in Korea. But growth rate of total assets(-2.21%), and growth rate of patient revenue(1.89%) is low. And salaries(53.39%), materials costs(16.62%), administrative expenses(28.58%) were different to the average of all oriental medicine hospitals in Korea(respectively 35.3%, 10.7%, 45.1%). Meanwhile, the cost ratio of the oriental medicine hospitals of University was 98.59%. It was 7.49% higher than the 91.1% of the average of all oriental medicine hospitals in 2011. Correlation analysis, growth rate of patient revenue and operating margin increased at the same time, and net profit to gross revenues and net profit to total assets with a growth rate of total assets increased. And administrative expenses and profitability indicators showed a negative correlation. It means, in order to improve the profitability of the oriental medicine hospitals of University should focus on reducing administrative expenses. Multiple regression analysis, growth rate of total assets, total assets turnover, administrative expenses, and salaries has affected the profitability. Therefore, in order to improve the profitability of the oriental medicine hospitals of University to increase the total capital and the total capital turnover, and to reduce administrative expenses effort.

• Journal of the Korean GEO-environmental Society
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• v.15 no.4
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• pp.5-11
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• 2014

Recently, there have been various lifeline installations constructed in the underground space of urban area due to the effective use of land. For newly installed lifelines or the management of the installed lifelines, many construction activities of excavation and backfilling are observed. Around these area, there are possibilities of collapse or excessive settlement due to the leaking of the pipe or unsatisfactory compaction of backfill material. Besides, construction costs can be saved since the on-site soils are used. The application of this liquidity filling material is not only to the lifeline installation but also to underpin the foundation under the vibrating machinery. On the evaluation of the applicability of this method to this circumstance, the strength should be investigated against the static load from the machine load as well as the vibration load from the activation of the machine. In this study, the applicability of the liquidity fill material on the foundation under the vibrating machinery is assessed via uniaxial compression and resonant column tests. The liquidity filling material consisting of the on-site soils with loess and kaolinite are tested to investigate the static and dynamic characteristics. Furthermore, the applicability of the reclaimed ash categorized as an industrial waste is evaluated for the recycle of the waste to the construction materials. The experimental results show that the shear modulus and 7 day uniaxial strength of the liquidity filling material mixed with reclaimed ash show higher than those with the on-site soils. However, the damping ratio does not show any tendency on the mixed materials.

• Food Science and Preservation
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• v.15 no.6
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• pp.847-851
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• 2008

The handling and processing of agricultural products in Korea is done manually. Small plastic boxes, nets, and corrugated cardboard boxes are used as containers during harvesting, sorting and other product handling operations. However, these practices are labor-intensive, time-consuming, require various kinds of packing materials, and are expensive because of high operating costs. To overcome these problems, the use of pallet bins with pre-cooling and storage features for handling and processing bulk farm products was investigated. The airflow resistances through bulk potato, onion and mandarin stocks were measured, and the pallet bins and a pressure pre-cooling device were manufactured. The opening ratio, bed depth and airflow rate through bulk potato, onion and mandarin in the pallet bin were defined with regression equations. The cooling rates of bulk potato, onion and mandarin were 0.8C/h ($21.7{\rightarrow}0C$, 14.5 h), 0.4C/h ($15.4{\rightarrow}.0C$, 32.2 h) and 0.7C/h ($13.7{\rightarrow}C$, 18.8 h), respectively, with the pressure pre-cooling system. Temperature deviances for storage of bulk potato, onion and mandarin were 0.12C, 0.12C and 0.17C, respectively.

• Journal of Environmental Impact Assessment
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• v.13 no.3
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• pp.125-135
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• 2004

Environmental Impact Assessment(EIA) in Korea has been used to improve environmental conservation and decision-making. Since environmental impact statement(EIS) was introduced in 1981 with the promulgation of the Environmental Preservation Act in 1977, which replaced the Pollution Control Act legislated in 1963. With a rapid growth of environmental perception as well as the diversification of development activities, however, it has recently bring about a strong demand for a new assessment process related to the strategic level of policies, plan, programs. Method of this study includes analyses of the situation of local EIA and its problematic issues through survey and analysis of information and data, analysis of the level of environmental awareness of professionals and case studies including analysis of foreign strategic environmental assessment. Accordingly, I have elicited a concept of SEA. In addition, I have studied on costs of environmental assessment, and efficiency of internalization of HIA. The survey was carried between September and November 2003, and 177 professionals were asks to complete a questionnaire. As a result of questionnaire survey of environmental pundits, it revealed that 83.8% of participants were in favor of introduction of strategic assessment. This result demonstrated more or less higher approval rate than those of awareness survey done by the Ministry of Environment, i.e. 86.0% ayes, and 14.0% nays. 22.8% of participants agreed to the opinion; "For introduction of this system, earlier is better," 50% reported having an opinion such as, "Will introduce this system in an earliest possible time after correcting problems," 26.3% reported having an opinion such as, "Let's decide the time for introduction of this system after correcting problems first,' and 0.9% reported having an opinion, "it's too early to introduce this system." Specifically, the ratio of ayes on introduction of the system marked 72.8%, and it revealed that a majority of respondents have an opinion such as, "Will introduce this system in an earliest possible time after correcting problems." As means of solutions for the problem regarding the limits of applications that existed in SEA System, factors, such as collecting a wide variety of opinions, securing experts, and faithful implementation, etc. were reported important, and in addition to these factors, respondents revealed having opinions such as, consistent research and development, reflection of public interest, establishment of professional organization, enforcement of after-management service, expanding investments in large, systemizing reference materials, and encouraging public participation, etc. To improve problems involving with present EIA system, it has been identified through this study that SEA is efficient and useful. In order to have SEA introduced successfully, it has been cleared that internalization of effectiveness of environmental cost together with HIA must be accomplished.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.433-433
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• 2012

As the requirement in patterning geometry continuously shrinks down, the termination of etch process at the exact time became crucial for the success in nano patterning technology. By virtue of real-time optical emission spectroscopy (OES), etch end point detection (EPD) technique continuously develops; however, it also faced with difficulty in low open ratio etching, typically in self aligned contact (SAC) and one cylinder contact (OCS), because of very small amount of optical emission from by-product gas species in the bulk plasma glow discharge. In developing etching process, one may observe that coupon test is being performed. It consumes costs and time for preparing the patterned sample wafers every test in priority, so the coupon wafer test instead of the whole patterned wafer is beneficial for testing and developing etch process condition. We also can observe that etch open area is varied with the number of coupons on a dummy wafer. However, this can be a misleading in OES study. If the coupon wafer test are monitored using OES, we can conjecture the endpoint by experienced method, but considering by data, the materials for residual area by being etched open area are needed to consider. In this research, we compare and analysis the OES data for coupon wafer test results for monitoring about the conditions that the areas except the patterns on the coupon wafers for real-time process monitoring. In this research, we compared two cases, first one is etching the coupon wafers attached on the carrier wafer that is covered by the photoresist, and other case is etching the coupon wafers on the chuck. For comparing the emission intensity, we chose the four chemical species (SiF2, N2, CO, CN), and for comparing the etched profile, measured by scanning electron microscope (SEM). In addition, we adopted the Dynamic Time Warping (DTW) algorithm for analyzing the chose OES data patterns, and analysis the covariance and coefficient for statistical method. After the result, coupon wafers are over-etched for without carrier wafer groups, while with carrier wafer groups are under-etched. And the CN emission intensity has significant difference compare with OES raw data. Based on these results, it necessary to reasonable analysis of the OES data to adopt the pre-data processing and algorithms, and the result will influence the reliability for relation of coupon wafer test and whole wafer test.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.588-588
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• 2013

Nanoscale noble-metals have attracted enormous attention from researchers in various fields of study because of their unusual optical properties as well as novel chemical properties. They have possible uses in diverse applications such as devices, transistors, optoelectronics, information storages, and energy converters. It is well-known that nanoparticles of noble-metals such as silver and gold show strong absorption bands in the visible region due to their surface-plasmon oscillation modes of conductive electrons. Silver nanocubes stand out from various types of Silver nanostructures (e.g., spheres, rods, bars, belts, and wires) due to their superior performance in a range of applications involvinglocalized surface plasmon resonance, surface-enhanced Raman scattering, and biosensing. In addition, extensive efforts have been devoted to the investigation of Gold-based nanocomposites to achieve high catalytic performances and utilization efficiencies. Furthermore, as the catalytic reactivity of Silver nanostructures depends highly on their morphology, hollow Gold nanoparticles having void interiors may offer additional catalytic advantages due to their increased surface areas. Especially, hollow nanospheres possess structurally tunable features such as shell thickness, interior cavity size, and chemical composition, leading to relatively high surface areas, low densities, and reduced costs compared with their solid counterparts. Thus, hollow-structured noblemetal nanoparticles can be applied to nanometer-sized chemical reactors, efficient catalysts, energy-storage media, and small containers to encapsulate multi-functional active materials. Silver nanocubes dispersed in water have been transformed into Ag@Au nanoboxes, which show highly enhanced catalytic properties, by adding $HAuCl_4$. By using this concept, $SiO_2$-coated Ag@Au nanoboxes have been synthesized via galvanic replacement of $SiO_2$-coated Ag nanocubes. They have lower catalytic ability but more stability than Ag@Au nanoboxes do. Thus, they could be recycled. $SiO_2$-coated Ag@Au nanoboxes have been found to catalyze the degradation of 4-nitrophenol efficiently in the presence of $NaBH_4$. By changing the amount of the added noble metal salt to control the molar ratio Au to Ag, we could tune the catalytic properties of the nanostructures in the reduction of the dyes. The catalytic ability of $SiO_2$-coated Ag@Au nanoboxes has been found to be much more efficient than $SiO_2$-coated Ag nanocubes. Catalytic performances were affected noteworthily by the metals, sizes, and shapes of noble-metal nanostructures.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.200-200
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• 2010

In recent times, metal oxide semiconductors thin films transistor (TFT), such as zinc and indium based oxide TFTs, have attracted considerable attention because of their several advantageous electrical and optical properties. There are many deposition methods for fabrication of ZnO-based materials such as chemical vapor deposition, RF/DC sputtering and pulsed laser deposition. However, these vacuum process require expensive equipment and result in high manufacturing costs. Also, the methods is difficult to fabricate various multicomponent oxide semiconductor. Recently, several groups report solution processed metal oxide TFTs for low cost and non vacuum process. In this study, we have newly developed solution-processed TFTs based on Ti-related multi-component transparent oxide, i. e., InTiO as the active layer. We propose new multicomponent oxide, Titanium indium oxide(TiInO), to fabricate the high performance TFT through the sol-gel method. We investigated the influence of relative compositions of Ti on the electrical properties. Indium nitrate hydrate [$In(NO^3).xH_2O$] and Titanium isobutoxide [$C_{16}H_{36}O_4Ti$] were dissolved in acetylacetone. Then monoethanolamine (MEA) and acetic acid ($CH_3COOH$) were added to the solution. The molar concentration of indium was kept as 0.1 mol concentration and the amount of Ti was varied according to weighting percent (0, 5, 10%). The complex solutions become clear and homogeneous after stirring for 24 hours. Heavily boron (p+) doped Si wafer with 100nm thermally grown $SiO_2$ serve as the gate and gate dielectric of the TFT, respectively. TiInO thin films were deposited using the sol-gel solution by the spin-coating method. After coating, the films annealed in a tube furnace at $500^{\circ}C$ for 1hour under oxygen ambient. The 5% Ti-doped InO TFT had a field-effect mobility $1.15cm^2/V{\cdot}S$, a threshold voltage of 4.73 V, an on/off current ratio grater than $10^7$, and a subthreshold slop of 0.49 V/dec. The 10% Ti-doped InO TFT had a field-effect mobility $1.03\;cm^2/V{\cdot}S$, a threshold voltage of 1.87 V, an on/off current ration grater than $10^7$, and a subthreshold slop of 0.67 V/dec.