• Journal of the Korean housing association
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• v.11 no.1
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• pp.171-181
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• 2000

The purpose of the resent research is to investigate the characteristics of sound insulation at the circular voided concrete slab in the multi-housing. In order to do this research, the method for field measurement of floor impact sound level was used following the Korea Standard F2810-1996. For the multi-housing, three kinds of circular voided concrete slabs are used to measure the characteristics of sound insulation.The results are as follows; 1.The main factor affecting the characteristics of sound insulation at the circular voided concrete slab in the multi-housing is sound-absorbing materials in the circular tube. 2. The main factor to effect the difference of sound pressure level is circular tube in the concrete slab. 3. The forms of circular tubes effect the characteristics of sound insulation at the circular tube. 4. Sound Pressure Level resulting from the piping direction of circular tubes in little different to octave band level.More study will be needed about the depth and distance of sound insulation materials, and the components of sound insulation materials for the multi-housing.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.52-61
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• 2003

This study was carried out to analyze the effects of stormwater retention and infiltration pond on reduction of flood peak and volume in a experimentally developed ecological pond. The experimental site has 542$m^2$ watershed area, 1,310mm yearly-averaged rainfall. And the area of the retention pond is 60$m^2$, the maximum water depth is 0.5m, the maximum and average storage is 15$m^3$and 9.3$m^3$d. And the area of infiltration pond is 58$m^2$, and the water depth varies 0.2m~0.5m. The monitoring system consists of one rainfall gage, one Parshall flume and acoustic water level gage, two rectangular weirs and acoustic water level gage for discharge gaging, and one data recording unit. Data from ten storm events in total, three storm events in year 2000 and seven storm events in year 2001, were collected. From the data the evaporation rate was achieved with the water balance equation, and the result shows 5.0mm/day in average. The result from the analysis of the effects on reduction of flood peak and volume, is that 14% reduction of flood volume and 15% reduction of flood peak in retention pond and 49% reduction of flood volume in infiltration pond.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1245-1248
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• 2004

This paper presents a new technique to analyze data on the coordinate x, y, z and apply these data to design the motion control to improve the efficiency of the engraving machine so that it can engrave accordingly in 3 dimensions. First, the tool path on the x-y plane is analyzed to be synchronized with the z-axis. The digital data is then sent to the motion control to guide the movement of the engrave point on the x-y plane. Tool path moves along the x-axis with zero degree and different values of the y-axis according to the coordinate of the digital data and the analysis along z-axis to determine the depth for engraving. The depth can be specified from the gray level with the 256 levels of resolution. The data obtained includes the distances on x-axis, y-axis, and z-axis, the acceleration of the engrave point's movement, and the speed of the engrave point's movement. These data is then transfered to the motion control to guide the movement of the engrave point along the z-axis associated with the x-y plane. The results indicate that engraving using this technique is fast and continuous. The specimen obtained looks perfect in 3D view.

• Steel and Composite Structures
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• v.34 no.3
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• pp.321-332
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• 2020

The loss of composite action at the hogging moment zone for a continuous composite girder reduces the girder stiffness and strength. This paper presents an experimental investigation of the use of an ultra-high performance concrete (UHPC) slab at the hogging moment zone and a normal concrete (NC) slab at the sagging moment zone. The testing was conducted to verify the level of loading at which composite action is maintained at the hogging moment zone. Four two-span continuous composite girders were tested. The thickness of the UHPC varied between a half and a full depth of slab. The degree of shear connection at the hogging moment zone varied between full and partial. The experimental results confirmed the effectiveness of the UHPC slab to enhance the girder stiffness and maintain the composite action at the hogging moment zone at a load level much higher than the upper service load limit. To a lesser degree enhanced performance was also noted for the smaller thickness of the UHPC slab and partial shear connection at the hogging moment zone. Plastic analysis was conducted to evaluate the ultimate capacity of the girder which yielded a conservative estimation. Finite element (FE) modeling evaluated the girder performance numerically and yielded satisfactory results. The results indicated that composite action at the hogging moment zone is maintained for the degree of shear connection taken as 50% of the full composite action and use of UHPC as half depth of slab thickness.

• Journal of Periodontal and Implant Science
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• v.30 no.3
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• pp.651-661
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• 2000

A mucogingival grafting procedure has been developed to cover denuded root surface. The subepithelial connective tissue graft technique is very predictable and allows for a good esthetic results and minimum patient discomfort on the palate. However, in areas where there is a lack of vestibular depth and keratinized attached tissue, the presence of frena or heavy muscle attachment, covering the connective tissue graft with a mucosal flap is very difficult. The purpose of this study is to evaluate an alternative technique of root coverage using the free connective tissue graft. The results were as follows: 1. Probing depths didn't seem to vary significantly from the preoperative to postoperative period. 2. The amount of keratinized tissue showed an increase of $5.9{\pm}0.97mm$ from the preoperative level. 3. Total clinical exposed root coverage increase 72.2% compare with preoperative level. 4. The shrinkage from gingival margin is $4.2{\pm}1.15mm$ and the mean shrinkage rate is 40.1%. 5. The depth of the vestibule increased with the average distance from cementoenamel junction to mucogingival junction being $7.4{\pm}1.65mm$.

• Korean Institute of Interior Design Journal
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• v.15 no.5 s.58
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• pp.183-192
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• 2006

This study analyzes the characteristics of special configuration for wayfinding in general hospitals. To that end, the study categorizes four different hospitals, according to the type of their wayfinding systems. It aims at utilizing the result of the analysis for wayfinding system in general hospitals by applying three elements of analysis methods', perpetual access, depth, and intelligibility. The study result shows as follows: First, there is no difference in special hierarchy when hospitals are analyzed and divided by halls and streets. It means that outpatient departments are located by spatial function and characteristics rather than form of spatial configuration. Second, we found that fewer direction changes are conducive to easier circulation in terms of wayfinding, when we analyzed spatial depth from the main entrances to the outpatient departments. Third, regarding intelligibility, intelligibility of Chungang University Hospital ranked highest. Kunkook University Hospital, Dongkook University Hospital and Seoul National University Hospital ranked 2nd, 3rd, and 4th respectively. It means that difficulty level of wayfinding is not decided by the characteristics of special configuration such as hospital hall and hospital streets but depends on location planning. The difficulty level of wayfinding mainly relies on location planning.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.63-68
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• 2006

Time series of waterline changes during a flood/ebb cycle can be utilized for supplementary data for measuring bottom topography. The waterlines extracted from consecutive images are substituted for depth contours using water level data. The distances between contours are quantified through a rectification image process. This technique is applied to the Keunpoolan beach in the Daeijak Island near Incheon. A camera monitoring technique supported by natural water level changes produces bottom topography with high precision. It is also less time consuming and more economical. The technique also can be utilized effectively to the physical modeling f3r measuring bottom changes in the three dimensional basin.

• Steel and Composite Structures
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• v.14 no.3
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• pp.295-312
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• 2013

In this paper, a simplified approach based on critical temperature for fire resistance design of steel-concrete composite beams is proposed. The method for determining the critical temperature and fire protection of the composite beams is developed on the basis of load-bearing limit state method employed in current Chinese Technical Code for Fire safety of Steel Structure in Buildings. Parameters affecting the critical temperature of the composite beams are analysed. The results show that at a definite load level, section shape of steel beams, material properties, effective width of concrete slab and concrete property model have little influence on the critical temperature of composite beams. However, the fire duration and depth of concrete slab have significant influence on the critical temperature. The critical temperatures for commonly used composite beams, at various depth of concrete and fire duration, are given to provide a reference for engineers. The validity of the practical approach for predicting the critical temperature of the composite beams is conducted by comparing the prediction of a composite beam with the results from some fire design codes and full scale fire resistance tests on the composite beam.

• Journal of The Korean Association For Science Education
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• v.21 no.5
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• pp.924-943
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• 2001

The purpose of the study is to analyze and compare the primary science curricula of Korea, China, and Japan. Science textbooks for Korea and China and national science curriculum guides for Korea and Japan were analyzed in terms of the scope and sequence of the topics. The number of primary science topics dealt with is greatest in China, followed by Korea, then Japan. In addition to the wide range of topics, the Chinese curriculum also shows more in-depth coverage of topics. On the contrary, the Japanese curriculum has the least number of topics and shallowest depth of coverage. Korea seems to be in the middle between China and Japan. The similarities of the curricula in these East Asian countries is greatest between Korea and China. and the least between China and Japan. The similarities between Korea and Japan is somewhere in the middle. Korean primary science curriculum shows a comparatively even distribution of topics across grades. A relatively smaller number of sub-topics are introduced at each grade level, especially in the area of earth science and physics. On the contrary, in the Chinese curriculum, sub-topics tend to be concentrated at a certain grade level, thus major topics are dealt with in a grade or two. The Japanese science curriculum has fewer topics than those of the other countries, and generally one or two sub-topics appeared in a grade or two.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.636-639
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• 2003

It is difficult to machine below 10 micrometers by conventional machining methods, such as micro-EDM. However, ultra micro machining using focused ion beam(FIB) is able to machine to 50 nanometers. In addition, 3 dimensional structures can be made by a combination of FIB and CVD to the level of 10 nanometers. Die ＆ moulds techniques are better than one-to-one machining techniques in the mass production of ultra size structures, in regards to production costs. In this case, the machining precision of die ＆ moulds affects produced parts. Also, it is advantageous to machine die ＆ moulds to the 10 micrometer level by FIB technique rather than other techniques. In this paper, the grooving characteristics for die ＆ mould materials by FIB were carried out experimentally in order to compare the machining characteristics of FIB with conventional machining methods. The results showed that the machining parameters and the scanning path of FIB affects the precision. The machined width and depth of the groove varied depending on the required depth due to the redeposition of the sputtered ion material accumulating on both the bottom and the side of the wall.