• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.12
• /
• pp.689-695
• /
• 2015

A biofilm filtration for the removal of gaseous pollutants has been recognized as a process with a complex interaction between the gas flow characteristics and the process operating variables. This study aims to develop an one dimensional dynamic numerical model which can be utilized as a tool for the analysis of biofilm filtration process operated in plug flow mode. Since, in a plug flow system, minor environmental changes in a gaseous unit process cause a drastic change in reaction and the interaction between the pollutants is an influencing factor, plug flow system was generalized in developing the model. For facilitation of the model development, dispersion was simplified based on the principles of material balance. Several reactions such as competition, escalation, and control between the pollutants were included in the model. The applicability of the developed model was evaluated by taking the calibration and verification steps on the experimental data performed for the removal of BTX at both low and high flow concentration. The model demonstrated a correlation coefficient ($R^2$) greater than 0.79 under all the experimental conditions except for the case of toluene at high flow condition, which suggested that this model could be used for the generalized gaseous biofilm plug flow filtration system. In addition, this model could be a useful tool in analyzing the design parameters and evaluating process efficiency of the experiments with substantial amount of complexity and diversity.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.5
• /
• pp.182-199
• /
• 2023

Since 2021, government departments have been promoting Automated Driving Technology Development and Innovation Project as national research and development(R&D) project. The automated vehicles and service technologies developed as part of these projects are planned to be subsequently provided to the public at the selected Living Lab City. Therefore, it is important to determine a spatial area and operation section that enables safe and stable automated driving, depending on the purpose and characteristics of the target service. In this study, the static Operational Design Domain(ODD) elements for Level 4 automated driving services were reclassified by reviewing previously published papers and related literature surveys and investigating field data. Spatial analysis techniques were used to consider the reclassified ODD elements for level 4 in the real area of level 3 automated driving services because it is important to reflect the spatial factors affecting safety related to real automated driving technologies and services. Consequently, a total of six driving mode changes(disengagement) were derived through spatial information analysis techniques, and the factors affecting the safety of automated driving were crosswalk, traffic light, intersection, bicycle road, pocket lane, caution sign, and median strip. This spatial factor analysis method is expected to be useful for determining special areas for the automated driving service.

• Geophysics and Geophysical Exploration
• /
• v.9 no.1
• /
• pp.73-85
• /
• 2006

Array observations of the vertical component of microtremors are frequently conducted to estimate a subsurface layered-earth structure on the assumption that microtremors consist predominantly of the fundamental mode Rayleigh waves. As a useful tool in the data collection, processing and analysis, the spatial autocorrelation (SPAC) method is widely used, which in practice requires a circle array consisting of M circumferential stations and one centre station (called "M-station circle array", where M is the number of stations). The present paper considers the minimum number of stations required for a circle array for efficient data collection in terms of analytical efficacy and field effort. This study first rearranges the theoretical background of the SPAC algorithm, in which the SPAC coefficient for a circle array with M infinite is solely expressed as the Bessel function, $J_0(rk)$ (r is the radius and k the wavenumber). Secondly, the SPAC coefficient including error terms independent of the microtremor energy field for an M-station circle array is analytically derived within a constraint for the wave direction across the array, and is numerically evaluated in respect of these error terms. The main results of the evaluation are: 1) that the 3-station circle array when compared with other 4-, 5-, and 9-station arrays is the most efficient and favourable for observation of microtremors if the SPAC coefficients are used up to a frequency at which the coefficient takes the first minimum value, and 2) that the Nyquist wavenumber is the most influential factor that determines the upper limit of the frequency range up to which the valid SPAC coefficient can be estimated.

• Economic and Environmental Geology
• /
• v.25 no.1
• /
• pp.27-39
• /
• 1992

Several pyrophyllite deposits occur around the Milyang area where Cretaceous andesitic rocks and spatially related granitic rocks are widely distributed. Pyrophyllite ores consist mainly of pyrophyllite, and quartz with small amount of sericite, pyrite, dumortierite, and diaspore. The andesitic rocks and spatially related granitic rocks in this area suggest that they could be formed from the same series of a calc-alkaline magma series. The contents of $SiO_2$, $Al_2O_3$, LOI(loss on ignition) are enriched, and $K_2O$, $Na_2O$, CaO, MgO, $Fe_2O_3$ are depleted in altered andesitic rocks and ores. Enrichment of As, Cr, Sr, V, Sb and depletion of Ba, Cs, Ni, Rb, U, Y, Co, Sc, Zn are characteristic during mineralization. The pyrophyllite ores can be discriminated from the altered-and unaltered wall-rocks by an increasing of $(La/Lu)_{cn}$ from 4.18~22.13 to 8.98~55.05. In R-mode cluster analysis, Yb-Lu-Y, La-Ce-Hf-Th-U-Zr, $TiO_2-V-Al_2O_3$, Sm-Eu, $CaO-Na_2O-MnO$, Cu-Zn-Ag, $K_2O-Rb$ are closely correlated. In the discriminant analysis of multi-element data, $P_2O_5$, As, Cr and $Fe_2O_3$, Sr are helpful to identify the ores from the unaltered-and altered wall-rocks. In the factor analysis, the factors of alteration of andesitic rocks and ore mineralization were extracted. In the change of ions per unit volume, $SiO_2$, $Al^{3+}$ and LOI are enriched and $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Mn^{2+}$ and $Fe^{3+}$ are depleted during the alteration processes. The Milyang and the Sungjin pyrophyllite deposits could be mineralized by hydrothermal alteration in a geochemical condition of low activity ratio of alkaline ions to hydrogen ion with reference to spatially related granitic rocks.

• Journal of Energy Engineering
• /
• v.29 no.2
• /
• pp.68-78
• /
• 2020

According to the new climate change agreement, technology development to reduce greenhouse gases is actively conducted worldwide, and research on energy efficiency improvement in the field of power generation and transmission and distribution is underway [1,2]. Economic analysis of the operation method of storing and supplying surplus electricity using energy storage devices, and using energy storage devices as a frequency adjustment reserve power in regional cogeneration plants has been reported as the most profitable operation method [3-7]. Therefore, this study conducted an economic analysis for the installation of energy storage devices in the combined heat and power plant in the Czech Republic. The most important factor in evaluating the economics of battery energy storage devices is the lifespan, and the warranty life is generally 10 to 15 years, based on charging and discharging once a day. For the simulation, the ratio of battery and PCS was designed as 1: 1 and 1: 2. In general, the primary frequency control is designed as 1: 4, but considering the characteristics of the cogeneration plant, it is set at a ratio of up to 1: 2, and the capacity is simulated at 1MW to 10MW and 2MWh to 20MWh according to each ratio. Therefore, life was evaluated based on the number of cycles per year. In the case of installing a battery energy storage system in a combined heat and power plant in the Czech Republic, the payback period of 3MW / 3MWh is more favorable than 5MW / 5MWh, considering the local infrastructure and power market. It is estimated to be about 3 years or 5 years from the simple payback period considering the estimated purchase price without subsidies. If you lower the purchase price by 50%, the purchase cost is an important part of the cost for the entire lifetime, so the payback period is about half as short. It can be, but it is impossible to secure profitability through the economy at the scale of 3MWh and 5MWh. If the price of the electricity market falls by 50%, the payback period will be three years longer in P1 mode and two years longer in P2 and P3 modes.

• Restorative Dentistry and Endodontics
• /
• v.29 no.2
• /
• pp.170-176
• /
• 2004

Objectives : In the unique metal iris method. the developing interfacial gap at the cavity floor resulting from the cavity wall property during polymerizing composite resin might affect the nominal shear bond strength values. The aim of this study is to evaluate that the iris method reduces the cohesive failure in the substrates and the cavity wall property effects on the shear bond strength tests using iris method. Materials and Methods : The occlusal dentin of 64 extracted human molars were randomly divided into 4 groups to simulate two different levels of cavity wall property (metal and dentin iris) and two different materials ($ONE-STEP^{\circledR}$ and $ALL-BOND^{\circledR}$ 2) for each wall property. After positioning the iris on the dentin surface. composite resin was packed and light-cured. After 24 hours the shear bond strength was measured at a crosshead speed of 0.5 mm/min. Fracture analysis was performed using a microscope and SEM. The data was analyzed statistically by a two-way ANOV A and t-test. Results : The shear bond strength with metal iris was significant higher than those with dentin iris (p＝0.034). Using $ONE-STEP^{\circledR}$, the shear bond strength with metal iris was significant higher than those with dentin iris (p＝0.005), but not in $ALL-BOND^{\circledR}$ 2 (p＝0.774). The incidence of cohesive failure was very lower than other shear bond strength tests that did not use iris method. Conclusions：The iris method may significantly reduce the cohesive failures in the substrates. According to the bonding agent systems. the shear bond strength was affected by the cavity wall property.

• The Korean Journal of Quaternary Research
• /
• v.4 no.1
• /
• pp.41-57
• /
• 1990

Gravel shapes of the terrace gravel sequences are compared with the present river gravels and beach gravels in the Pohang and its surrounding areas. Seventeen gravel textural parameters are divided into 5 groups based on R-mode factor analysis. Among them, three parameters (RDm, MPSm, SZstd) are selected for a test of discriminant possibility of palaeoenvironment of the terrace gravel deposits. Marine gravels are in the range of 0.49 to 0.75 in mean roundness, 0.46 to 0.78 in mean maximum projection sphericity and 0.39 to 1.85 in standard deviation of size, whereas river gravels are 0.28 to 0.51 in mean roundness, 0.66 to 0.72 in mean maximum projection sphericity and 1.04 to 1.81 in standard deviation of size. For practical access to the palaeoenvironment discrimination, a bivariant diagram between mean roundness and mean maximum projection sphericity is the most effective. The marine terrace gravels are plotted within the variation range of present beach gravels and show 0.49 to 0.71 in mean roundness and 0.59 to 0.66 in mean maximum projection sphericity. The gravels of river terrace vary within the range of gravels derived from present river bed and are characterized as 0.36 to 0.48 in mean roundness and 0.66 to 0.71 in mean maximum projection sphericity.

• The Korean Journal of Quaternary Research
• /
• v.5 no.1
• /
• pp.15-31
• /
• 1991

A total of 90 surface sediment samples, collected from the continental margin area bordering east and southeast coast of Korea, were subject to the geochemical analyses with the aim of filling the gap in our knowledge of this environment. The analyzed items included the major elements (Al, Fe, Mg, Ca, K, Na, p and Mn), organic carbon, and some trace metals (Ba, Co, Cu, Sr and Zn). The sediment grain-size exerted a predominant influence on the contents of most elements, with the exceptions of Ca, K, Sr and Ba. The Ca and Sr contents, being closely interrelated each other, were mainly controlled by the calcium carbonate content. The K content, on the other hand, appeared to be influenced by both illite and feldspar. The Ba content showed a certain relationship with that of K, suggesting a common source of these two elements; potassium feldspar. The R-mode factor analysis result also reaffirmed the above-mentioned controlling factors on the sediment geochemistry. The grain-size dependency of trace metals obscures their areal distribution pattern from the total contents. However, with the metal/aluminum ratios we could differentiate the subtle difference in the metal enrichment. Hence, sediments of the southern coastal area appear to receive some anthropogenic inputs of metals, though the effect is still negligible.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.4 no.3
• /
• pp.215-225
• /
• 1999

To study the vertical variations of major elements, trace elements and rare earth elements(REEs) contents in deep-sea sediments, six cores from Korea Deep-sea Environmental Study area(KODES) were analyzed. Topmost sediment layers of KODES area are divided into two Units; brown-colored and peneliquid Unit I and pale brown-colored and relatively solidified Unit II. Contents of major elements, REEs, Cu, Sr and Rb in each Unit are almost same, while contents of Mn, Ni and Co in Unit I are two or three times higher than those in Unit II. R-mode factor analysis represents that surface sediments are composed of alumino-silicate phase (AI-Ti-K-Mg-Fe-Rb-Ce), apatite phase (Ca-P-Cu-Sr-Trivalent Rare Earth Elements) and Mn-oxide phase(Mn-Ni-Co). Factor scores in silicate and apatite phases in each Unit are nearly same, whereas those in Mn-oxide phase in Unit I is higher than those in Unit II. While NilCu ratio in Unit I is two times higher than that in Unit II. We interprete the geochemical fractionation of Ni and Cu as a result that Ni can be remobilized in oxygen-depleted micro-environment in Units I and II and then easily reprecipitated in Unit I, while most of Cu supplied together with organic material is decomposed mostly in Unit I and sorbed into apatite.

• Journal of Global Scholars of Marketing Science
• /
• v.18 no.4
• /
• pp.61-118
• /
• 2008

The purpose of this research is to construct research framework for international franchising based on existing literature and to identify research components in the framework. Franchise can be defined as management styles that allow franchisee use various management assets of franchisor in order to make or sell product or service. It can be divided into product distribution franchise that is designed to sell products and business format franchise that is designed for running it as business whatever its form is. International franchising can be defined as a way of internationalization of franchisor to foreign country by providing its business format or package to franchisee of host country. International franchising is growing fast for last four decades but academic research on this is quite limited. Especially in Korea, research about international franchising is carried out on by case study format with single case or empirical study format with survey based on domestic franchise theory. Therefore, this paper tries to review existing literature on international franchising research, providing research framework, and then stimulating new research on this field. International franchising research components include motives and environmental factors for decision of expanding to international franchising, entrance modes and development plan for international franchising, contracts and management strategy of international franchising, and various performance measures from different perspectives. First, motives of international franchising are fee collection from franchisee. Also it provides easier way to expanding to foreign country. The other motives including increase total sales volume, occupying better strategic position, getting quality resources, and improving efficiency. Environmental factors that facilitating international franchising encompasses economic condition, trend, and legal or political factors in host and/or home countries. In addition, control power and risk management capability of franchisor plays critical role in successful franchising contract. Final decision to enter foreign country via franchising is determined by numerous factors like history, size, growth, competitiveness, management system, bonding capability, industry characteristics of franchisor. After deciding to enter into foreign country, franchisor needs to set entrance modes of international franchising. Within contractual mode, there are master franchising and area developing franchising, licensing, direct franchising, and joint venture. Theories about entrance mode selection contain concepts of efficiency, knowledge-based approach, competence-based approach, agent theory, and governance cost. The next step after entrance decision is operation strategy. Operation strategy starts with selecting a target city and a target country for franchising. In order to finding, screening targets, franchisor needs to collect information about candidates. Critical information includes brand patent, commercial laws, regulations, market conditions, country risk, and industry analysis. After selecting a target city in target country, franchisor needs to select franchisee, in other word, partner. The first important criteria for selecting partners are financial credibility and capability, possession of real estate. And cultural similarity and knowledge about franchisor and/or home country are also recognized as critical criteria. The most important element in operating strategy is legal document between franchisor and franchisee with home and host countries. Terms and conditions in legal documents give objective information about characteristics of franchising agreement for academic research. Legal documents have definitions of terminology, territory and exclusivity, agreement of term, initial fee, continuing fees, clearing currency, and rights about sub-franchising. Also, legal documents could have terms about softer elements like training program and operation manual. And harder elements like law competent court and terms of expiration. Next element in operating strategy is about product and service. Especially for business format franchising, product/service deliverable, benefit communicators, system identifiers (architectural features), and format facilitators are listed for product/service strategic elements. Another important decision on product/service is standardization vs. customization. The rationale behind standardization is cost reduction, efficiency, consistency, image congruence, brand awareness, and competitiveness on price. Also standardization enables large scale R&D and innovative change in management style. Another element in operating strategy is control management. The simple way to control franchise contract is relying on legal terms, contractual control system. There are other control systems, administrative control system and ethical control system. Contractual control system is a coercive source of power, but franchisor usually doesn't want to use legal power since it doesn't help to build up positive relationship. Instead, self-regulation is widely used. Administrative control system uses control mechanism from ordinary work relationship. Its main component is supporting activities to franchisee and communication method. For example, franchisor provides advertising, training, manual, and delivery, then franchisee follows franchisor's direction. Another component is building franchisor's brand power. The last research element is performance factor of international franchising. Performance elements can be divided into franchisor's performance and franchisee's performance. The conceptual performance measures of franchisor are simple but not easy to obtain objectively. They are profit, sale, cost, experience, and brand power. The performance measures of franchisee are mostly about benefits of host country. They contain small business development, promotion of employment, introduction of new business model, and level up technology status. There are indirect benefits, like increase of tax, refinement of corporate citizenship, regional economic clustering, and improvement of international balance. In addition to those, host country gets socio-cultural change other than economic effects. It includes demographic change, social trend, customer value change, social communication, and social globalization. Sometimes it is called as westernization or McDonaldization of society. In addition, the paper reviews on theories that have been frequently applied to international franchising research, such as agent theory, resource-based view, transaction cost theory, organizational learning theory, and international expansion theories. Resource based theory is used in strategic decision based on resources, like decision about entrance and cooperation depending on resources of franchisee and franchisor. Transaction cost theory can be applied in determination of mutual trust or satisfaction of franchising players. Agent theory tries to explain strategic decision for reducing problem caused by utilizing agent, for example research on control system in franchising agreements. Organizational Learning theory is relatively new in franchising research. It assumes organization tries to maximize performance and learning of organization. In addition, Internalization theory advocates strategic decision of direct investment for removing inefficiency of market transaction and is applied in research on terms of contract. And oligopolistic competition theory is used to explain various entry modes for international expansion. Competency theory support strategic decision of utilizing key competitive advantage. Furthermore, research methodologies including qualitative and quantitative methodologies are suggested for more rigorous international franchising research. Quantitative research needs more real data other than survey data which is usually respondent's judgment. In order to verify theory more rigorously, research based on real data is essential. However, real quantitative data is quite hard to get. The qualitative research other than single case study is also highly recommended. Since international franchising has limited number of applications, scientific research based on grounded theory and ethnography study can be used. Scientific case study is differentiated with single case study on its data collection method and analysis method. The key concept is triangulation in measurement, logical coding and comparison. Finally, it provides overall research direction for international franchising after summarizing research trend in Korea. International franchising research in Korea has two different types, one is for studying Korean franchisor going overseas and the other is for Korean franchisee of foreign franchisor. Among research on Korean franchisor, two common patterns are observed. First of all, they usually deal with success story of one franchisor. The other common pattern is that they focus on same industry and country. Therefore, international franchise research needs to extend their focus to broader subjects with scientific research methodology as well as development of new theory.