• Journal of Wetlands Research
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• v.21 no.4
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• pp.334-343
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• 2019

A lab-scale vertical flow subsurface (VFS) wetland composed of three parallel columns with polypropylene synthetic fiber as main substrate was operated. Piggery stormwater diluted from swine excreta was fed to the wetland on the basis of three different hydraulic regimes or hydraulic retention time (HRT) of 2, 4, and 8 days with daily internal recirculation. Then, monitoring of common water quality parameters was carried out. Unexpectedly, an increase of effluent COD concentration accompanying the appearance of foams was observed during a distinct period in the wetland with HRT 2, 4, and 8 days, successively. Subsequently, a series of experiments was conducted to investigate the origin of the foams. Foams and the increase of COD concentration were found to be induced by the release of organic matter from the synthetic polypropylene fiber which was fed with piggery stormwater. Meanwhile, nitrogen removal was found to be enhanced during a period which overlapped the distinct foaming period signifying that foaming played two important functions in biological nitrogen removal. Foams which form rapidly and then burst easily could hold up and then release oxygen for nitrification. Foams which contain organic surfactants could serve as carbon sources for denitrification as well. Hence, nitrogen removal was enhanced during the foaming stage. After that, COD concentration decreased slowly to a level prior to the foaming stage, and nitrogen removal efficiency declined as well.

• Journal of Life Science
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• v.26 no.6
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• pp.651-656
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• 2016

Bee pollen is produced by honeybees and is considered one of the most balanced and nourishing nutritional supplements available. Historically, bee pollen has been prescribed for its healing properties and consumed for its high-energy supply. Recent research has provided evidence that bee pollen has diverse biological activities, such as anti-oxidant, anti-inflammatory, anti-bacterial, and even anti-cancer effects. However, the outer membrane of the pollen grain, exine, is highly resistant to most acidic solutions, high pressure, and even digestive enzymes, and the resulting low bioavailability limits its nutritional and clinical applications. This study applied a wet-grinding method to destroy the exine effectively, and it then examined the pollen's enhanced biological activity. First, microscopic observations provided strong evidence that wet grinding destroyed the exine time-dependently. In addition, the content of polyphenols, well-known ingredients of bee pollen and used as internal standards for the quality control of commercial pollen preparations, increased up to 11-fold with wet grinding. Further, the anti-oxidant activity demonstrated on the ABTS anti-oxidant assay, as well as the DPPH radical scavenging assay, was also dramatically increased. Together, the results presented here support a new technology by which bee pollen can be used as a resource for medical, nutritional, and cosmetic applications.

• Journal of Preventive Medicine and Public Health
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• v.34 no.1
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• pp.9-20
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• 2001

Objectives : To explore the relationship between Percutaneous Transluminal Coronary Angioplasty(PTCA) volume and the associated immediate outcome. Methods : A total of 1,379 PTCAs were peformed in 25 hospitals in Korea between October 8 and December 31 in 1997. Data from 1,317 PTCAs (95.5%) were collected through medical record abstraction. Inter-observer reliability of the data was examined using the Kappa statistic on a subsample of 110 PTCA procedures from five hospitals. Intra-observer reliability of the data was also examined. PTCA success and immediate adverse outcomes were selected as the outcome variables. A successful PTCA was defined as a case that shows less than 50% diameter stenosis and more than 20% reduction of diameter stenosis. Immediate adverse outcomes included deaths during the same hospitalization, emergency coronary artery bypass graft (CABG) within 24 hours after PTCA, and acute myocardial infarction within 24 hours after PTCA. The numbers of PTCAs performed in 1997 per hospital were used as the volume variables. Results : Without adjusting for patient risk factors that may affect outcomes, procedures at high volume hospitals ($\geq200$ cases per year) had a greater success rate (P=0.001) than low volume hospitals. There was a marginally significant difference (P=0.070) in major adverse outcome rates between high and low volume hospitals. After adjusting for risk factors, there were significant differences in procedural failure and major adverse outcome rates between high and low volume hospitals. Conclusions : After adjusting for patient clinical risk factors, the hospital volume of PTCA was associated with immediate outcomes. It is recommended that a PTCA volume per year be established in order to improve the immediate outcome of this procedure in Korea.

• Korean Journal of Construction Engineering and Management
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• v.15 no.3
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• pp.23-30
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• 2014

Overseas construction orders of domestic companies had been increased significantly in a short period from $10.9 billion in 2005 to $64.9 billion in 2012. However experts are concerned that quality of growth will not support quantitative growth. This study suggest concentrate competencies for not only winning in bid but also successful execution of domestic companies. 4 Steps which are Pre-Marketing, Bid-Preparation, Bidding, Contract Phase are defined for competency assessment. After drawing specific tasks by phase, survey asking importance and capability of the tasks to the person in charge of bidding and site was conducted by utilizing Likert 7 point scale. According to the result of IPA analysis, domestic construction companies need to ensure internal competencies; Project risk review, Bid team organization, and external competencies; Client needs grasp, Localization strategy, Cooperation establishment. Hearafter domestic construction companies will be able to utilize the result of the study for setting bidding strategy for winning in bid and improving earning rate.

• 대한공업교육학회지
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• v.44 no.2
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• pp.123-141
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• 2019

The purpose of this study is to provide basic data that can be used for the development of technology textbooks of Nigeria-Korea Model School by analyzing external and internal aspects of Illustration in Nigerian primary school technology textbooks, and 10 textbooks used in Nigeria were analyzed. Based on the results of the study, the conclusions are as follows. First, the form of the visual data should be diversified into a picture, a cartoon, a diagram, and a diagram from the photograph center, and provide various information closely related to the contents of the technology. Second, it is necessary to increase the size of illustration so as to induce learners to be motivated, and to enhance the effect of editing. Third, currently, partial enlargement data is rarely used, but visual material should be partially enlarged in order to express a detail part of product. Fourth, diversity of editing should be done by using circular or background omission rather than using only rectangle uniformly in visual material. Fifth, in terms of gender equality, it is necessary to deviate from male-centric visual materials and edit them with consideration for women. Sixth, in order to provide learner-centered textbooks, the role of visual materials should be extended to 'inducement of motivation', 'activity guidance', and 'activity result' in addition to 'providing data'. Finally, in terms of the function of visuals, the quality of textbooks should be upgraded by utilizing auxiliary and decorative functions in addition to essential functions.

• Journal of the Korean association of regional geographers
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• v.7 no.2
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• pp.17-34
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• 2001

This paper is to analyze how firms in a large firm-led industrial city have carried out the restructuring in the face of radical shifts, with focus on the strategy and the restructuring of firms in Ulsan, a typical industrial district in Korea that is specialized in heavy & chemical industry. It has been well known that the local economy has been led by a small number of large firms, including affiliates of chaebol, and its industrial structure has also been characterised as a clear dichotomy between large firms as a customer and small and medium-size firms as a supplier, which can be called not horizontal but vertical relations. It can identify some tendencies, however, that local companies have been rather dynamically changing in response to increasingly turbulent environment since the Asian crisis. Some are radical, but some incremental. These can be summarized in four distinctive but interlinked ways. First, more than half of local companies surveyed have attempted to change their production systems, mainly from the fordist mass production towards the flexible mass production, seeking both economies of scale and scope. Second, local firms have vigorously continued to reorganize the boundary of the production and the organization, by specializing products and focusing on the core competence in order to save costs and cope with radically changing customer demands in a flexible way. Third, there have been various strategies for the organizational innovation such as the introduction of team organization, the boundary blurring between the managerial and production workers and the intra-firm spin-offs, so as to improve managerial efficiency and competence in the use of internal labour market. Finally, they have tried to be more sensitive to the market and customers. These tendencies seem to be increasingly critical to sustain their competitiveness. To do so, they tend to focus increasingly not only on the competing via the product quality rather than through price, but also to seek to diversify the market and customer firms beyond national boundary.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.32-41
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• 2015

The Metropolitan Area Green Heat Project (MAGHP), which collects unused heat gathered from power plants, steel works, landfills in western Metropolitan area and distribute it to integrated energy business (IEB) companies, is proposed for the purpose of enhancing energy efficiency and providing low-price heat for IEB companies. Therefore, in order to decide on whether to initiate the MAGHP, the economic feasibility analysis of the project is widely demanded. This paper attempts to consider and measure four economic benefits: heat supply benefit, production cost reduction benefit, greenhouse gas mitigation benefit, and air quality improvement benefit. In addition, the paper tries to conduct the economic feasibility analysis. The project requires three-year investment and thirty-year operation. Three important findings emerge from the analysis. First, its net present value is computed to be 1,269 billion won and more than zero. Second, its benefit/cost ratio is calculated to be 1.72 and bigger than 1.0. Third, its internal rate of return is estimated to be 24.26% and larger than the social rate of return, 5.5%. In conclusion, the MAGHP is socially profitable and should be conducted immediately.

• Design & Manufacturing
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• v.11 no.2
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• pp.51-56
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• 2017

Nitinol, a shape memory alloy (SMA), is manufactured from titanium and nickel and it used in various fields such as electrical applications, micro sensors. It is also recommended as a material in medical for implant because it has excellent organic compatibility. Nitinol is intended to be inserted into the human body, products require a high-quality surface and low residual stress. To overcome this problems, explore electrolyte polishing (EP) is being explored that may be appropriate for use with nitinol. EP is a particularly useful machining method because, as a non contact machining method, it produces neither machining heat nor internal stress in the machined materials. Sandpaper polishing is also useful machining method because, as a contact machining method, it can easily good surface roughness in the machined materials. The electrolyte polishing (EP) process has an effect of improving the surface roughness as well as the film polishing process, but has a characteristic that the residual stress is hardly generated because the work hardened layer is not formed on the processed surface. The sandpaper polishing process has the effect of improving the surface roughness but the residual stress remains in the surface. We experimented with three conditions of polishing process. First condition is the conventional polishing. Second condition is the electrochemical polishing(EP). And Last condition is a mixing process with the conventional polishing and the EP. Surface roughness and residual stress of the nitinol before a polishing process were $0.474{\mu}mRa$, -45.38MPa. Surface roughness and residual stress of the nitinol after mixing process of the conventional polishing and the EP were $1.071{\mu}mRa$, -143.157MPa. Surface roughness and residual stress of the nitinol after conventional polishing were $0.385{\mu}mRa$ and -205.15MPa. Surface roughness and residual stress of sandpaper and EP nitinol were $1.071{\mu}mRa$, -143.157MPa. The result shows that the EP process is a residual stress free process that eliminates the residual stress on the surface while eliminating the deformed layer remaining on the surface through composite surface machining rather than single surface machining. The EP process can be used for biomaterials such as nitinol and be applied to polishing of wafers and various fields.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.366-375
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• 2017

Internal factors having effects on compressive strength test results of concrete include size, shape, height-diameter ratio(h/d), section processing method, dryness and wetness, etc. of the specimen. As it is difficult to ensure dimensions of core specimen due to rebar cutting from rebar spacing, wall thickness, effects on the structure, etc. when taking core of the concrete structure, correction of dimensions and h/d of the specimen become important for quality control of the concrete. Thus, in order to review effects of specimen size and height-diameter ratio for the concretes with compressive strength within 40~60MPa, this study has experimentally reviewed compressive strength test values by applying correction factors pursuant to KS F 2422 (Method of obtaining and testing drilled cores and sawed beams of concrete), when changing specimen diameter to ${\emptyset}5{\sim}15cm$, and h/d to 2.0~1.25.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2371-2385
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• 2010

What are the success factors of IT venture entrepreneur that through initial phase and enter to the growth phase ? Both the duration of jobless growth and the economic recession are worsening employment market. Entrepreneurship is be proposed to a method for creating jobs and reducing the economic gap. Research on Entrepreneurship and the support of government policy has already been operated for a long time ago. Research on growth and duration of the entrepreneur in initial phase, compared with growth phase are insignificant in quantity or quality. Therefore, this study researches essential factors about growth and duration of the entrepreneur in the initial phase through cases related them. entrepreneur of this subject are classified the hardware development group and the software development group associated with manufacturing characteristic funded existence. There is a research on evaluation factors about selection and result evaluation of selecting Entrepreneur. And this can be investigated by studying to Entrepreneur's growth and duration in initial phase. There are affecting factors about growth and duration of first step. And they are divided by internal, external, synthetic, and characteristic factors of growth phase. The result of this study is be used to develop pre-established educational program, consulting guidelines and establish support policy.