• Journal of the Korean Geosynthetics Society
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• v.7 no.4
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• pp.37-45
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• 2008

A pilot test using environmentally friendly drains, was carried out to evaluate their applicability potential in the field. The pilot test site was divided into 5 different areas, with several combinations of vertical and horizontal drains installed for evaluation. Conventional natural fiber drains (FDB), new developed straw drain board (SDB) and plastic drain board (PDB) were used as vertical drains, while sand and fiber mats were used as horizontal drains. Surface settlement rates and excess pore pressure generation/dissipation tendency of PDB and FDB are almost identical except those of SDB. Cone tip resistance obtained from cone penetration test measured at the end of 1st consolidation stage for upper soft layer definitely increased irrespective of types of vertical drains. The monitoring and site investigation test data obtained at the pilot test site prove the vertical natural fiber drains can be used as substitutes of conventional plastic and sand material.

• Journal of the Korean Geosynthetics Society
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• v.5 no.2
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• pp.45-50
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• 2006

Although the discharge capacity of the natural fiber drains are very low compared to that of plastic drain board (PDB), it is found that the conventional fiber drains and the new developed straw drain boards have great potential for use as a substitute for conventional plastic drain boards through several model tests. To verify their field application, a pilot test using environmentally friendly drains is also being carried out to prove their effective discharge capacity in the field. The pilot test site was divided into 5 different areas, with various combinations of vertical and horizontal drains installed for evaluation. Definite characteristics of various drains are still to be found due to the delay in construction of embankment. Consolidation behavior of three types of vertical drains and two types of horizontal drains will be analyzed after the completion of the embankment in the near future.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.105-105
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• 2003

Theoretical studies have been performed for drainage and filtration characteristics, low consolidation rate of sandmat and prefabricated horizontal and vertical drain. Discussion on quality control and methodology, cost analysis for sandmat and prefabricated horizontal drains were performed.

• Journal of the Korean Geosynthetics Society
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• v.4 no.1
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• pp.27-36
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• 2005

Discharge capacity of the fiber mat and the fiber drain made with natural fibers abstracted from plant source was evaluated by permeability test for fiber mat and Delft type test and composite discharge capacity test using disturbed clayey soils for fiber drain. The permeability test results for environmentally friendly coconut fiber mat prove that fiber mat has outstanding permeability in substituting permeable sand. However, discharge capacity of fiber drain evaluated by conventional Delft type discharge capacity test was relatively lower than that of plastic drain board. Nevertheless, settlement and pore pressure dissipation behaviors of fiber drain and plastic drain board installed clay soil during the composite discharge capacity test were almost similar to that of plastic drain board. It is found that the natural fiber drain satisfies requiring minimum discharge capacity in substituting the conventional plastic drain board.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.5 s.118
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• pp.9-15
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• 2006

Wet compaction test (WCT) is a fiber evaluation method where wet fibers are compressed at one side of a cylinder and water drains out from the other side. The consistency of the fiber furnishes and their pressures are recorded during the test. In the previous study we found that WCT results always gave better coefficients of determination in fiber furnish drainage, and paper properties (density, tensile, tear, and burst strength) than those of WRV (water retention value). Fiber freeness and fiber length correlated well with drainage and tear strength of the furnishes, respectively; however, their correlations were very much improved by combining the WCT results. In this study, we used the WCT test for fractionated fiber furnishes to see whether improvement of the WCT is possible. We found that strength properties such as breaking length and burst index were correlated better with the fractionated long fiber furnishes. Drainage was greatly affected by the presence of short fiber furnishes. We used bleached chemical pulps (SwBKP, HwBKP), recycled pulp (OCC), and mechanical pulp (BCTMP) as fiber furnishes in this study. Fiber fractionation can be performed on-line in these days by using multifractor and WCT can be used as an on-line test in papermachine in the future.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.349-356
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• 2003

Almost every material of PVD (Prefabricated Vertical Drain) has the fatal problem on the condition - the length must shorten with the settlement of the surrounding grounds - which all PVDs must satisfy. Kinking deformation by buckling of PVD due to consolidation settlement Is discussed in this paper. A new testing device to clarify the deformation of PVD under consolidation of surrounding clay was developed and the fiber drain and a PVD made of plastics were compared under the same condition of consolidation using natural clay specimens. The results are also shown in this paper.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.15-21
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• 2008

Long term changes of hydraulic properties and tensile strength of natural fiber drain (NFD) are analyzed and compared with those of intact NFD's. NFD was buried in distilled water, two types of seawater and clay soils obtained in southern and western parts of Korea, Kwang-Yang and Si-hwa. Specimens are taken out in 0, 3, 9 and 18 month intervals, and durability tests of the NFD are performed. Hydraulic conductivity of the NFD samples decreased compared with that of intact NFD samples, because clay particles easily passed to coarsened mesh of filters and clogged the porous stone below and reduced hydraulic conductivity. Tensile strength of drains from the soil bucket is reduced larger than those in the seawater and the distilled water. Strength reduction was higher in summer than winter.

• Journal of the Korean Geosynthetics Society
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• v.4 no.3
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• pp.3-10
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• 2005

This paper aims at investigating the characteristics of discharge capacity according to lateral pressure, hydraulic gradient and deformation of drain materials. A series of experiments were conducted to achieve this objective. In experiments, fiver drain boards as well as harmonica and castle types of drain boards were installed in a rubber membrane, and clay in sully was filled around them. The test results showed that the harmonica type of drain boards have the greatest discharge capacity comparing to castle and fiber drain boards. The results also indicated that the hydraulic gradient has more effect on reduction of discharge capacity than the lateral pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.133-144
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• 2009

Incheon Bridge, 18.4 km long sea-crossing bridge, will be opened to the traffic in October 2009 and this will be the new landmark of the gearing up north-east Asia as well as the largest & longest bridge of Korea. Incheon Bridge is the integrated set of several special featured bridges including a magnificent cable-stayed girder bridge which has a main span of 800 m width to cross the navigation channel in and out of the Port of Incheon. Incheon Bridge is making an epoch of long-span bridge designs thanks to the fully application of the AASHTO LRFD (load & resistance factor design) to both the superstructures and the substructures. A state-of-the-art of the geotechnologies which were applied to the Incheon Bridge construction project is introduced. The most Large-diameter drilled shafts were penetrated into the bedrock to support the colossal superstructures. The bearing capacity and deformational characteristics of the foundations were verified through the world's largest static pile load test. 8 full-scale pilot piles were tested in both offshore site and onshore area prior to the commencement of constructions. Compressible load beyond 30,000 tonf pressed a single 3 m diameter foundation pile by means of bi-directional loading method including the Osterberg cell techniques. Detailed site investigation to characterize the subsurface properties had been carried out. Geotextile tubes, tied sheet pile walls, and trestles were utilized to overcome the very large tidal difference between ebb and flow at the foreshore site. 44 circular-cell type dolphins surround the piers near the navigation channel to protect the bridge against the collision with aberrant vessels. Each dolphin structure consists of the flat sheet piled wall and infilled aggregates to absorb the collision impact. Geo-centrifugal tests were performed to evaluate the behavior of the dolphin in the seabed and to verify the numerical model for the design. Rip-rap embankments on the seabed are expected to prevent the scouring of the foundation. Prefabricated vertical drains, sand compaction piles, deep cement mixings, horizontal natural-fiber drains, and other subsidiary methods were used to improve the soft ground for the site of abutments, toll plazas, and access roads. Light-weight backfill using EPS blocks helps to reduce the earth pressure behind the abutment on the soft ground. Some kinds of reinforced earth like as MSE using geosynthetics were utilized for the ring wall of the abutment. Soil steel bridges made of corrugated steel plates and engineered backfills were constructed for the open-cut tunnel and the culvert. Diverse experiences of advanced designs and constructions from the Incheon Bridge project have been propagated by relevant engineers and it is strongly expected that significant achievements in geotechnical engineering through this project will contribute to the national development of the longspan bridge technologies remarkably.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.4
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• pp.21-27
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• 2001

Korean traditional paper (Hanji) making technology has adopted two kinds of sheet forming processes, which called "Oebal-choji": and "Ssangbal-choji". The sheet forming process of Oebal-choji is an original method developed in Korea. At first, paper stock is dipped onto the mold and flow away in the forward direction. Then, paper stock is scooped again and rhythmically rocked from side to side, this work is repeated several times. Through this operation the fibers intertwine and paper layers are formed. Ssangbal-choji is almost same as the Nagashizuki, which used in Japan. In this method, paper stock is scooped onto the mold and rhythmically rocked backwards and forwards several times, the water drains slowly through the bamboo screen and then sheet is formed. Tamezuki method is used in Japan and China. This is a method in which the mold is dipped into the paper stock once and left to drain. In the Ssangbal-choji and Nagashizuki methods, the most of excess solution is cast out while in the Tamezuki all of it is allowed to drain through the mold. This study was carried out to investigate the physical properties of the Hanjis that were made by Oebal-choji, Ssangbal-choji, Nagashizuki, and Tamezuki sheet forming processes. The results were follows; Physical properties of the Oebal-choji Hanji were better than those of Ssangbal-choji, Nagashizuki, and Tamezuki. Oebal-choji Hanji made little difference of paper strength between MD and CD, but Ssangbal-chjo and Nagashizuki Hanjis made wide difference. And there are no difference of paper strength between MD and CD on the Tamezuki Hanji. On the confocal laser scanning microscopy (CLSM) observation of the Hanjis, Oebal-choji made well crossed fiber orientation than those of other forming processes.r forming processes.