• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.779-788
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• 2019

The compaction grouting method is one of the conventional ground improvement methods, which consolidates and compacts the surrounding ground through the injection of grout materials with low mobility. Injecting the grout into the ground can improve the soil properties, as well as form a composite of soil-grout columns. However, the conventional grout pumping is not applicable to handle multiple injection holes at the same time, which may diminish its constructability when the construction time is not enough. This paper proposes a simultaneous multiple compaction-grouting method using a new pump system developed to cover up simultaneously three injection holes at a time. Field injection tests with a single injection hole and with triangular arrangement of injection holes were conducted to evaluate the applicability of the proposed method to soft clay ground. In addition, a series of standard penetration tests (SPTs) were performed to assess the efficiency of each arrangement in improving the soft ground. It is noted from the in-situ test results that the interval distances between injection holes and the elapse time for ground stabilization are the crucial factors governing the applicability of the simultaneous multiple compaction-grouting method to improve the soft clay ground.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.4
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• pp.129-139
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• 2015

Parks in order to find the inspiration and implication from their construction. The research is focused on a few cross-sectional city wall parks, which are Huangchenggen city wall park, Ming city wall park and Yuandadu city wall park. to come to the conclusion, it defines the generic concept of city wall park, clarifies the transitional process of the city of Beijing, organize the current situation and basis of the construction of the Beijing city wall parks. besides, by analyzing the Beijing city wall parks' specific construction manners including the basis of their planning, the support by government, planning functionality, landscape theme arrangement and gardening arrangement, the research puts forwards their construction characters and drawbacks. through comprehensive analysis on the aspects above, a series of inspirations are obtained for the construction of city wall parks. these include: specialized and legally valid regulation systems need to be setup before planning; government and citizens' proactive support is necessary for the protection of ancient city wall ruins and the construction of the city wall parks; when planning, existing situation should be utilized to the maximum extent, efficiency of space usage should be improved through smooth connection between different spacial locations.

• Journal of the Korean Solar Energy Society
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• v.37 no.4
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• pp.1-11
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• 2017

Most PV modules are fabricated by 6 cell-strings with solar cells connected in series. Moreover, bypass diodes are generally installed every 2 cell-strings to prevent PV modules from a damage induced by current mismatch or partial shading. But, in the case of special purpose PV module, like as BIPV (Building Integrated Photovoltaic), the number of cell-strings per module varies according to its size. Differ from a module employing even cell-strings, the configuration of bypass diode should be optimized in the PV module with odd strings because of oppositely facing electrodes. Hence, in this study, electrical characteristics of special purposed PV module with odd string was empirically and theoretically studied depending on arrangement of bypass diode. Here, we assumed that PV module has 3 strings and the number of bypass diodes in the system varies from 2 to 6. In case of 2 bypass diodes, shading on a center string increases short circuit current of the module, because of a parallel circuit induced by 2 bypass diodes connected to center string. Also, the loss is larger, as the shading area in the center string is enlarged. Thus, maximum power of the PV module with 2 bypass diode decreases by up to 59 (%) when shading area varies from 50 to 90 (%). On the other hand, In case of 3 and 6 bypass diodes, the maximum power reduction was within about 3 (W), even the shading area changes from 50 to 90 (%). As a result, It is an alternative to arrange the bypass diode by each string or one bypass diode in the PV module in order to completely bypass current in case of shading, when PV module with odd string are fabricated.

• Journal of Navigation and Port Research
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• v.30 no.3 s.109
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• pp.173-179
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• 2006

A number of perforated plates are utilized for the passage of the crew and the equipment, reducing weight and the arrangement of piping. Hull girders in double bottom and floor plates are the typical parts which have those plates in a ship structure, and the perforated plate is usually positioned at the place which has less loading without local strength problems. In the case of utilizing the plate inevitably at the place which has large strength, an opening of the plate has large effect on the buckling strength due to in-plane rigidity and ultimate strength. Therefore the assessments of the elastic buckling strength and the ultimate strength for the perforated plate are the essential requirements for determining the dimensions of the parts at the initial design stage. With above reason, a need of the reasonable assessments for the elastic buckling strength and the ultimate strength has evolved. The numerical series analysis with the consideration of the effect due to various aspect ratios and slenderness ratios were performed using finite element method in this research. Simple formulas for the design are also proposed from the above analysis.

• Polymer(Korea)
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• v.33 no.1
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• pp.58-66
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• 2009

The thermotropic liquid crystalline behavior of the homologous series of cellulose tri[4-{4'-(nitrophenylazo) phenoxycarbonyl}] alkanoates (NACEn, n=2$\sim$8, 10, the number of methylene units in the spacer) have been investigated. All of the homologoues formed monotropic nematic phases. The isotropic-nematic transition temperature ($T_{iN}$) decreased when n is increased up to 7, but it became almost constant when n is more than 7. The plot of transition entropy at $T_{iN}$ against n had a sharp negative inflection at n=7. The sharp change at n=7 may be attributed to the difference in arrangement of the side groups. The melting temperature ($T_m$) and associated entropy change at $T_m$, in contrast with $T_{iN}$ and associated entropy change at $T_{iN}$, exhibited a distinct odd-even effect, suggesting that the average shape of the side chains in the crystalline phase is different from that in the nematic phase. The thermal stability and degree of order of the nematic phase observed for NACEn were significantly different from those reported for the homologous series of side-chain and combined type liquid crystal polymers bearing azobenzene or biphenyl units in the side chains. The results were discussed in terms of the differences in the chemical structure, the flexibility of the main chain, the mode of chemical linkage of the side group with the main chain, and the number of the mesogenic units per repeating unit.

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.364-370
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• 2009

The aim of this study was to evaluate the effect of fiber direction on the polymerization shrinkage of fiber-reinforced composite. The disc-shaped flowable composite specimens (d = 10 mm, h = 2 mm, Aeliteflo A2, Bisco, Inc., IL, USA) with or without glass fiber bundle (X-80821P Glass Fiber, Bisco, Inc., IL, USA) inside were prepared, and the longitudinal and transversal polymerization shrinkage of the specimens on radial plane were measured with strain gages (Linear S-series 350${\Omega}$, CAS, Seoul, Korea). In order to measure the free polymerization shrinkage of the flowable composite itself, the disc-shaped specimens (d = 7 mm, h = 1 mm) without fiber were prepared, and the axial shrinkage was measured with an LVDT (linear variable differential transformer) displacement sensor. The cross-section of the polymerized specimens was observed with a scanning electron microscope to examine the arrangement of the fiber bundle in composite. The mean polymerization shrinkage value of each specimen group was analyzed with ANOVA and Scheffe post-hoc test (${\alpha}$=0.05). The radial polymerization shrinkage of fiber-reinforced composite was decreased in the longitudinal direction of fiber, but increased in the transversal direction of fiber (p<0.05). We can conclude that the polymerization shrinkage of fiber-reinforced composite splint or restoratives is dependent on the direction of fiber.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.96-100
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• 2004

In the ship building industry various problems of erection is counterfeited due to formation of bottle necks in the block erection flow pattern This kind of problems cause accumulated problems in real-time erection right on the floor, When such a problem is approached, a support data of the entire erection sequence should be available, Here planning is done by reasoning about the future events in order to verify the existence of a reasonable series of actions to accomplish a goal. This technique helps in achieving benefits like handling search complications, in resolving goal conflicts and anticipation of bottleneck formation well in advance to take necessary countermeasures and boosts the decision support system, The data is being evaluated and an anticipatory function is to be developed This function is quite relevant in day to day planning operation. The system updates database with rearrangement of off-critical blocks in the erection sequence diagram, As a result of such a system, planners can foresee months ahead and can effectively make decisions regarding the control of loads on the man, machine and work flow pattern, culminating to an efficient load management. Such a foreseeing concept helps us in eliminating backtracking related adjustment which is less efficient compared to the look-ahead concept. An attempt is made to develop a computer program to update the database of block arrangement pattern based on heuristic formulation.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.744-754
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• 2016

Asphalt concrete track (ACT) is a track system connecting wide sleepers and concrete panels on top of an asphalt concrete layer; such a system requires adequate resistance force against various longitudinal and lateral external loads. In this study, a series of experiments were carried out to assess the longitudinal and lateral resistance force of a wide sleeper and concrete panel type ACT. The required shear resistance force of the horizontal displacement restraint device (HDRD) was evaluated. Furthermore, a concrete block type anchor and a steel pipe type anchor were developed as HDRDs. The shear resistance force was decided based on the experimental results of horizontal shear tests for each anchor system. In addition, proper numbers and arrangement design guidelines for the HDRDs were suggested considering the shear resisting capacity and economics for HDRDs applied to ACT.

• Journal of Educational Research in Mathematics
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• v.18 no.3
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• pp.283-308
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• 2008

A poor achievement of basic competency leads to obstacles of the same subject and other subjects from a series of accumulative losses and social life. The Grade 3 National Diagnostic Assessment of Basic Competency (NDAHC) dated from 2002, Teaching Plan Responsible to Basic Competency and compensational education materials for students of the below-basic level has marked a line in the chain of policy to realize educational welfare. The goal of NDABC is to collect information of the reason with regard to learning deficiency and individual student's information, and ultimately teach them on the basis of those informations. This study analyzed the characteristics of below-basic students in the basic mathematics with data from NDABC from 2003 to 2007. Students of the below-basic level were affected in achievement by numerical distinction, regrouping, arrangement and descriptive form of item, information-providing way, typical example, familiarity, frequency in use in daily life etc. This study provides a basic important information with regard to teaching below-basic students and suggestions with compensational education materials for them.

• Water for future
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• v.7 no.2
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• pp.11-22
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• 1974

Comparing with Seoul city's other administrative works, the work to arrange and collect monthly water rates with 470,000 faucets is tremendous in volume and simple repetition in quality. In order to cover the shortage of handling, it is urgent for us to replace the present manual system with EDP(Electronic Data Processing) system to mechanize a series of handling works of simple repeated calculation such as water consumption, rate calculation, statistics arrangement, bills and specification of water rate by computer. When this work is completely mechanized, inspectors of water meter just turn over their checking results to the Data Center and all data are processed through Input Media(OMR Card, Punched Card) and computer for programming final bills. Then, the delivery of the bills to citizens will be the only work to be carried out. such mechanization will bring about the following benefits: 1. Improvement of administrative work by efficiency and rationalization. 2. Improvement of administrative service with people. 3. Possibility of scientific with trustworthy multi-purpose policy-making data. 4. An effect to cover the personnel shortage of 252 persons (at all the water works offices) and save manpower of 166 persons (47,619 man-days). The application of the above mentioned mechanization will be started to only Chongro and Chung-ku water works offices as model cases out of all water works offices in Seoul. As the electronic calculating machines are inducted, this system will be gradually applied to other water works offices. The billing and collection works of water rates which are connected directly to the daily life of the citizenes, should be handled by the scientific EDP system as soon as possible in order to promote the convenience of consumers and effective operation. This study is to promote the sound and rational operation of this work.