• Title/Summary/Keyword: High-volume

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Dynamic Analysis of the Effect of Network Externality in Vertically Differentiated Market (수직적으로 차별화된 시장 하에서 망외부성이 미치는 영향에 대한 동태적 분석)

  • Cho, Hyung-Rae;Rhee, Minho
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.42 no.2
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    • pp.1-8
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    • 2019
  • Network externalities are essentially dynamic in that the value consumers feel about a product is affected by the size of the existing customer base that uses that product. However, existing studies on network externalities analyzed the effects of network externalities in a static way, not dynamic. In this study, unlike previous studies, the impact of network externalities on price competition in a vertically differentiated market is dynamically analyzed. To this end, a two-period duopoly game model was used to reflect the dynamic aspects of network externalities. Based on the game model, the Nash equilibria for price, sales volume, and revenue were derived and numerically analyzed. The results can be summarized as follows. First, if high-end product has strong market power, the high-end product vendor takes almost all benefits of the network externality. Second, when high-end product has strong market power, the low-end product will take over most of the initial sales volume increase. Third, when market power of high-end product is not strong, it can be seen that the effects of network externalities on the high and low-end products are generally proportional to the difference in quality. Lastly, if there exists a strong network externality, it is shown that the presence of low-end product can be more profitable for high-end product vendor. In other words, high-end product vendor has incentive to disclose some technologies for the market entrance of low-end product, even if it has exclusive rights to the technologies. In that case, however, it is shown that the difference in quality should be maintained significantly.

Enhancing the Performance of Polypropylene Fiber Reinforced Cementitious Composite Produced with High Volume Fly Ash (폴리프로필렌 섬유로 보강된 하이볼륨 플라이애시 시멘트 복합재료의 성능 향상 기법)

  • Lee, Bang Yeon;Bang, Jin Wook;Kim, Yun Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.3
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    • pp.118-125
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    • 2013
  • The synthetic fibers including Polyvinyl alcohol and Polyethylene fibers have been successfully used in the manufacture of high ductile fiber reinforced cementitious composites. Polypropylene (PP) fiber has also been used in composites, not for the purpose of achieving a high level of tensile ductility but to improve the fire resistance performance of concrete exposed to high temperatures. This paper discusses the method for enhancing the performance of composites supplemented with PP fiber. Five types of mixture proportions were designed with high volume fly ash for testing the performance of composites. Type I cement and fly ash F were used as binding materials. The water-to-binder ratio was 0.23~0.25, and the amount of PP fiber used was 2 vol%. Polystyrene bead were also used to increase the tensile ductility of composites. A series of experiments including slump, density, compression and uniaxial tension tests were performed to evaluate the performance of cementitious composites supplemented with PP fiber. From the test results, it was exhibited that the performance of composites supplemented with PP fiber can be enhanced by adopting the mechanics and statistics theory.

Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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An Analysis of Call Demands of Two Squads In Kyonggi Provincial fire and Disaster Headquarters (경기도 소방재난본부에 소속된 두 구급대의 출동수요 분석)

  • Uhm, Tai-Hwan
    • The Korean Journal of Emergency Medical Services
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    • v.6 no.1
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    • pp.77-86
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    • 2002
  • The purposes of this research which was conducted by surveying lost/added unit hours reports, unit hour demand analysis worksheets from prehospital care reports of two squads in Kyonggi Provincial Fire and Disaster Headquarters for 20 weeks (January 1, 2002 - May 20, 2002) are to get Unit Hour Utilizations. Call Demands such as Unit Hour Demand, Simple Average Demand, High Average Demand, Peak Average Demand, the High Actual Demand. The conclusions from this analysis were summarized as follows: (1) By revealing Unit Hour Produced 3223.9, Call Volume 964, Unit Hour Utilization 0.299 at the Squad A and Unit Hour Produced 3328.4, Call Volume 901, Unit Hour Utilization 0.271 at the Squad B induced Korean Squads to chance identification, definition, direction of Unit Hour Utilization. (2) By revealing Simple Average Demand 7.4 on Monday Tuesday, High Average Demand 9.6 on Tuesday Friday. Peak Average Demand 11.5 on Tuesday, the High Actual Demand 12 on Tuesday Wednesday at the Squad A and Simple Average Demand 6.8 on Sunday, High Average Demand 10.4 on Monday, Peak Average Demand 11.5 on Monday, the High Actual Demand 13 on Monday at the Squad B enabled Korean Squads to utilize System Status Management. (3) The Maximum Calls per Unit Hour were 115 for 23:00~23:59, the Minimum Calls per Unit Hour were 46 for 05:00~05:49 in two squads. The Maximum Calls per Unit Hour were 7.4 on Tuesday Saturday, the Minimum Calls per Unit Hour were 6.1 on Thursday at the Squad A. The Maximum Calls per Unit Hour were 7.3 on Monday Saturday, the Minimum Calls per Unit Hour were 5.6 on Thursday at the Squad B. (4) Analyzing demand for EMTs in the optimum emergency medical service of Korea, we have been able to utilize this Unit Hour Utilization in company with the established estimation methods such as international comparisons or the number of ambulances for scientific reasonable estimation. (5) These Call Demands which were limited to the demand time in this study will make us expect some following studies including demand time, demand time, demand map for Strategic Deployment.

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Study of The Relation between Smoke Component and Sensory Evaluation of Cigarettes with the Different Leaf Blending (엽배합 특성에 따른 담배 연기성분과 관능특성과의 상관관계 구명)

  • 황건중;이문수;나도영
    • Journal of the Korean Society of Tobacco Science
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    • v.25 no.2
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    • pp.144-153
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    • 2003
  • This study was carried out to determine the relationship between smoke components and sensory evaluation by changes tobacco leaf blending. Seven different cigarettes were made by adding different types of oriental, reconstituted and expanded tobacco leaves. 62 kinds of smoke components which were 6 of general components, 34 of semi-volatile and volatile components, 9 of acid components, and 13 of phenolic components were analyzed. Eight kinds of sensory item were evaluated and also electronic nose system data was collected. All smoke components and sensory characteristics of mainstream smoke were changed by the different blending. To determine the relationship between smoke components and sensory test, the correlation and regression analysis were carried out by using SPSS statistical program. Tar, pH, and CO showed a high correlation with sensory evaluation item. As tar related to hotness, CO have a high correlation with offensive aroma. Semi-volatile and volatile components of smoke related to sensory characteristics such as aroma, taste, irritation, hotness and smoothness. When propylene, l,3-butadiene, butane, isoprene, and 2-methylfuran showed a high correlation with aroma; methyl chloride, methanol, toluene, ethyl benzene showed a high correlation with irritation. Some acidic components and phenolic components of smoke also had a high relation to smoke volume. Especially the acidic components such as 2-furoic acid, 2-hydroxybutyric acid, phenylacetic acid and palmitic acid; the phenolic components such as 4-vinyl phenol, pyrocatechol, 3-methyl catechol, hydroquinone showed a high correlation with smoke volume. As using regression analysis, it was possible to estimate the results of sensory evaluation from the smoke analysis data. From the results of electronic nose system analysis, we can find the different pattern by adding expanded tobacco leaf.

High Switching Frequency and High Power Density Three-Level LLC Resonant Converter using Integrated Magnetics (Integrated Magnetics를 적용한 고속 스위칭 및 고전력밀도 3 레벨 LLC 공진형 컨버터)

  • Nam, Kyung-Hoon;Park, Chul-Wan;Bae, Ji-Hun;Ji, Sang-Keun;Ryu, Dong-Kyun;Choi, Heung-Gyoon;Han, Sang-Kyoo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.6
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    • pp.551-554
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    • 2017
  • This paper proposes a three-level LLC resonant converter using integrated magnetics (IM). Given that the switch voltage stress of the proposed converter is guaranteed to be half of the input voltage, the switching losses can be greatly reduced, thereby benefitting the high-frequency operation. To reduce the volume of reactive components such as transformers, high-frequency driving and planar core are applied. However, two resonant inductors and one transformer are required because of the three-level structure and the limited leakage inductance of the planar transformer for the resonant operation. Therefore, the effect of volume reduction is not very large. In order to solve these drawbacks, this paper proposes a new IM that integrates all magnetic elements used in the proposed three-level resonant converter by using the magnetizing inductor as a resonant inductor. The experimental results are presented by conducting a theoretical analysis of a prototype with 350 W to 800 kHz.

A Study of the Characteristics of the High-Flowable Concrete (고유동콘크리트의 특성에 관한 실험적 연구)

  • Jeon, Hyun-Kyu;Kim, Dae-Hoi;Lee, Jong-Chan;Ji, Suk-Won;Yoo, Taek-Dong;Seo, Chee-Ho
    • Journal of the Korea Institute of Building Construction
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    • v.3 no.2
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    • pp.129-134
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    • 2003
  • In this research, we used fly-ash and blast-furnace slag as substitute material of cement and fine aggregate, and we, through experiments, researched and analyzed the features of high-flowable concrete added high efficiency AE water reduction agent. The results are below. 1. Liquefaction generally presented high-slump flow value; on the other hand, partial segregation was observed in case of mixing proportion with 65 cm slump flow and above. This segregation was partially improved in accordance with mixing admixture. 2. Compressive strength according to mixing admixture and increasing mixing ratio of fly-ash were subject to be declined when it was initially cast-in, but its gap was improved when time was fully passed. 3. After mixing blast-furnace slag and fly-ash as substitute material, the result showed that the modulus of elasticity against freezing & melting was improved according to mixing blast-furnace slag and also increased in accordance with increasing pulverulent-body volume. 4. According to increasing the mixing volume of fly-ash, the durability factor was deteriorated because compressive strength became lower as well as air content was decreased when it was initially case-in. 5. The minimum air content to secure durability was 3.7%, for that reason, we had better secure admixture such as air entraining agent when cast-in high-flowable concrete.

Improving the brittle behavior of high-strength shielding concrete blended with lead oxide, bismuth oxide, and tungsten oxide nanoparticles against gamma ray

  • Mohamed Amin;Ahmad A. Hakamy;Abdullah M. Zeyad;Bassam A. Tayeh;Ibrahim Saad Agwa
    • Structural Engineering and Mechanics
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    • v.85 no.1
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    • pp.29-53
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    • 2023
  • High-strength shielding concrete against gamma radiation is a priority for many medical and industrial facilities. This paper aimed to investigate the gamma-ray shielding properties of high-strength hematite concrete mixed with silica fume (SF) with nanoparticles of lead dioxide (PbO2), tungsten oxide (WO3), and bismuth oxide (Bi2O3). The effect of mixing steel fibres with the aforementioned binders was also investigated. The reference mixture was prepared for high-strength concrete (HSCC) containing 100% hematite coarse and fine aggregate. Thirteen mixtures containing 5% SF and nanoparticles of PbO2, WO3, and Bi2O3 (2%, 5%, and 7% of the cement mass, respectively) were prepared. Steel fibres were added at a volume ratio of 0.28% of the volume of concrete with 5% of nanoparticles. The slump test was conducted to workability of fresh concrete Unit weight water permeability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity tests were conducted to assess concrete's engineering properties at 28 days. Gamma-ray radiation of 137Cs emits photons with an energy of 662 keV, and that of 60Co emits two photons with energies of 1173 and 1332 keV were applied on concrete specimens to assess radiation shielding properties. Nanoparticles partially replacing cement reduced slump in workability of fresh concrete. The compressive strength of mixtures, including nanoparticles was shown to be greater, achieving 94.5 MPa for the mixture consisting of 7.5 PbO2. In contrast, the mixture (5PbO2-F) containing steel fibres achieved the highest values for splitting tensile, flexural strength, and modulus of elasticity (11.71, 15.97, and 42,840 MPa, respectively). High-strength shielded concrete (7.5PbO2) showed the best radiation protection. It also showed the minimum concrete thickness required to prevent the transmission of radiation.

NEW QUANTITATIVE MEASURING TECHNIQUE FOR MICROLEAKAGE OF THE RESTORED TOOTH THROUGH 3D RECONSTRUCTION (3차원 재구성법을 이용한 수복물의 정량적 미세누출도 측정)

  • Ha, Sang-Yoon;Shin, Dong-Hoon
    • Restorative Dentistry and Endodontics
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    • v.29 no.5
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    • pp.413-422
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    • 2004
  • Established microleakage tests have their own disadvantages. In this study, 3D reconstruction method was tried to overcome these disadvantages. Four types of microleakage tests were used and relationships among them were estimated: penetrated dye volume: marginal adaptability: degree of dye penetration and relative penetrated length to cavity wall. Twenty-four Class V cavities were bulk filled with composite (Esthet X) following surface treatments: N group (no treatment): E group (etching only): T group (etching + Prime & Bond NT). 50% silver nitrate was used as a dye solution after thermocycling ($5^{\circ}C{\;}&{\;}55^{\circ}C$, 1.000 times). Teeth were serially ground with a thickness of 0.2 mm. Volume of dye penetration was estimated from a three-dimensionally reconstructed image with a software (3D-DOCTOR). Percentage of margin without gap was estimated from SEM and degree of dye penetration and the relative length of dye penetration to overall cavity wall were also estimated. ANOVA and Scheffe test for dye volume, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman's rho test for checking of relationships among methods were used. The results were as follows: 1. Dye penetration could be seen from several directions, furthermore, its volumetric estimation was possible. 2. Reverse relationship was found between dye volume and marginal quality (r = -0.881/ p = 0.004). 3. Very low relationship was seen between dye volume and two-dimensional tests (degree of dye penetration and relative length). However, 2D evaluation methods showed high relationship (p = 0.002-0.054) each other. 4. Three times vertical section could be recommended as a 2D test.

An Efficient Logical Volume Manager for SAN (SAN을 위한 효율적인 논리볼륨 관리자)

  • 최영희;남상수;오재철;유재수
    • Journal of Internet Computing and Services
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    • v.3 no.5
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    • pp.73-85
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    • 2002
  • A new architecture coiled the Storage Area Network(SAN) was developed in response to the requirements of high availability of data, scalable growth, and system performance, In order to use SAN more efficiently, most SAN operating system support storage virtualization concepts that allow users to view physical storage devices attached to SAN as a large volume virtually. A logical volume manager plays a key role in storage virtualization. It realizes the storage virtualization by mapping logical addresses to physical addresses, In this paper, we design and implement an efficient and flexible mapping method for logical volume manager. Additionally, to aid flexible mapping, we also design and implement free space management method, The mapping method in this paper supports a snapshot that preserves a volume image at certain time and on-line reorganization to allow users to add or remove storage devices to SAN even while the system is running.

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