• International Journal of Highway Engineering
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• v.4 no.4 s.14
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• pp.23-39
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• 2002

This study dealt with developing a new approach for finding properties which might represent rut resistance characteristics of asphalt mixture under static loading. Two aggregates, a normal asphalt (pen 60-80) and 5 polymer-modified asphalts were used in preparation of 12 dense-graded mixtures. Marshall mix design was used in determination of OAC and each mixture at the OAC was prepared for a newly-developed Kim test on Marshall specimen (S=10cm) and gyratory specimen (S=15cm), and for wheel tracking test. Kim test used Marshall loading frame and specimens were conditioned for 30min at $60^{\circ}C$ before loading through Kim tester an apparatus consisting of a loading column and a specimen and column holder Diameter (D) of column was 3cm and 4cm with each column having different radius (r) of round cut at the bottom. The static load was applied at 50mm/min in axial direction of the specimen, not in diametral direction. The maximum load ($P_{max}$) and vertical deformation (y) at $P_{max}$ point were obtained from the test. A strength value was calculated based on the $P_{max}$ r, D and y by using the equation $K_D = 4P_{max}/{\pi}(D-2(r-\sqrt{2ry-y^2}))^2$ and is defined as the deformation strength ($kgf/cm^2$). The values of $P_{max}$/y and $K_I=K_D/y$ were also calculated. In general the leading column diameter and radius of round cut were significant factors affecting $K_D$ and $P_{max}$ values while specimen diameter was not. The statistical analyses showed the $K_D$ had the best correlation with rut depth and dynamic stability. The next best correlation was found from $P_{max}$ which was followed by $P_{max}$/y and $K_I$ in order.

• Tunnel and Underground Space
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• v.21 no.4
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• pp.320-327
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• 2011

In this study, for stemming effect in blast of the mortar block body, the crushed granite sand as fine aggregate, which is waste rock obtained at the ○○ limestone mine, was investigated to compare with stemming materials such as sea sand, river sand, clayed soil and water can be acquired easily at the field. The mortar block body was manufactured with the dimensions of 50 cm width, 50 cm length and 70 cm height. The direct shear and sieve separator test were performed, and the properties of friction resistance were analyzed by the extrusion test for five stemming materials. Axial strain of steel bar and ejection velocity of stemming materials due to the explosive shock pressure in blasthole with the stemming length of 10 cm and 20 cm in the mortar blast test were measured by the dynamic data acquisition system. Among stemming materials, axial strain showed the largest value at the crushed granite sand as fine aggregate, and the ejection velocity was the smallest value at the stemming of water. The results has shown correlate with harden unit weight in blasthole, particle size distribution, shear resistance, and extrusion strength of stemming materials. The ejection velocity of stemming material at the mouth of blasthole and the axial strain of steel bar in the inside of blasthole tend to be inversely proportional to each other, represent exponentially.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.1-7
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• 2006

The Green Wall system, developed in Austria early 1960, is one of segmental concrete crib type earth retaining wall. Green wall is constructed as procedures that lay the front stretchers, rear stretchers and headers then making a rigid body through harden filled soil of interior cell. Green wall has pro-environmental advantages that able to grow grass in front space of stretchers and decrease cutting ground. In Europe, Green wall used without other reinforcement method. However, green wall used with other reinforcement method like a soil nailing because of environmental problem. This study was performed to introduce the design case by 'Two-Body Translation mechanism' to be able to consider distribution of earth pressure in the soil nailing when designing the green wall using soil nailing system. Also, this study attempts to evaluate the earth pressure change when advanced soil nailing system is constructed using $FLAC^{2D}$ ver. 3.30 program and 'Two-Body Translation mechanism'.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.9-15
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• 2006

The Green Wall system is one of segmental concrete crib type earth retaining wall. Green wall is constructed as procedures that lay the front stretchers, rear stretchers and headers then making a rigid body through harden filled soil of interior cell. Recently, Green Wall method is applied in variable cutting ground construction because of advantage which minimize to cut base ground. In case of Green Wall method is constructed with soil nail method, expect that total system stability will increase more than flexible facing because of facing stiffness is big. However, in this case of design, facing stiffness is not considered so that is poor economy. Hence, in this study, stability increasing effect of total system analyze about that soil nail method is constructed with rigidity facing like a Green Wall method. In present study, laboratory model tests was performed for analysis on stability increasing effect of total system about changing stiffness of facing. LEM analysis conducted for evaluation on safety factor of total system sliding that facing condition changed.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.673-679
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• 2005

According to continuous welded rails on a bridge, temperature changes bring about the expansion of the bridge deck,adding axial forces on the track. Moreover, the ballast on the bridge deck expansion joint is moved due to the bridge deck. The longer the bridge deck is, the greater the influence will be, loosening the ballast, causing track irregularities, and deteriorating passenger comfort. Considering the structure of the bridge itself and tolerance for track irregularities caused by the loosened ballast on the bridge, the maximum length of the deck should be less than 80 m, which is the same as the standard of French railways. In this study, the interaction between the expansion related to the bridge length and the irregularity in the longitudinal level, referring to measurements and maintenance work performed in high-speed railways, was analyzed. This research shows that the installation of a sliding plate or a vertical ballast stopper is not a good option, since it is difficult. On the other hand, the installation of a ZLR fastener or gluing is easy, but its influence is insignificant. In conclusion, switch tie tamping or manual tamping is more effective than other methods of what?

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.23-36
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• 2019

In this paper, field measurement of the Block Type Mechanically Stabilized Earth (MSE) wall curved section was performed, and the reinforced area of the curved part is studied through the result. MSE method has been applied to various fields because of easy construction and excellent economic efficiency, so that it can be easily access in our life. However due to lack of compaction and stress concentration phenomenon, cracks and collapse occur in the curve of MSE wall, which is important for safety. The cause of collapse is lack of research on curved section, lack of design criteria, lack of construction due to economical efficiency and shortening of construction period, insufficient compaction space. In this study, therefore, it was examined the existing design and construction standards, analyzed the cause through accident examples of the curved section of the Block Type MSE wall. As a result, the horizontal displacement of the curved section was 90% higher than that of the straight section and 60% higher than that of the concave section. In the case of the convex section in the curved section reinforcement region, the maximum displacement is shown in the H/2 section in the horizontal direction from the center of the MSE wall, and the range of influence from H is shown. In the case of the concave section, the maximum displacement is shown in the center, The minimum displacement was confirmed in H/4 section in the horizontal direction from the center of the MSE wall. As a basic study on the reinforcement area rehabilitation through the actual construction of block type MSE wall, the behaviors of the straight part and the curved part were compared and analyzed. And analyzed the reinforced area in order to reduce the damage of the stress concentration phenomenon and secure the safety.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.407-416
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• 2010

A new tunnel auxiliary method is proposed in this paper which utilizes the concept of cavity expansion for tuunel reinforcement by forming an umbrella arch on the roof of tunnel. When an inflatable pipe is inserted and expanded by pressure in the bore hole of umbrella arch, the ground around the bore hole can be compacted so that the stress condition above the tunnel perimeter is favorably changed. In order to verify the reinforcement effect of new concept, pilot-scale chamber test, trapdoor test and numerical analysis were performed and compared. In pilot-scale chamber test, three types of inflatable pipes are tested to verify the capability of expansion, and the results arc compared with analytical results obtained by applying cavity expansion theory and with results obtained from finite clement analysis, and the experimental results showed agreeable matches with analytical and numerical ones. Numerical analysis of a tunnel and trapdoor test applied with the inflatable pipes are also performed to figure out the reinforcement effect of the proposed techniques, and the results implied that the new method with 3 directional inflatable pipe (no pressure to downward direction) can contribute to reduce tunnel convergence and face settlement.

• Journal of Korean Society of Archives and Records Management
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• v.2 no.2
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• pp.1-38
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• 2002

This study examines the status quo of Korean archives and records management from the Governmental as well as professional activities for the development of the field in relation to the new legislation on records management. Among many concerns, this study primarily explores the following four perspectives: 1) the Government Archives and Records Services; 2) the Korean Association of Archives; 3) the Korean Society of Archives and Records Management; 4) the Journal of Korean Society of Archives and Records Management. One of the primary tasks of the is to build the special depository within which the Presidential Library should be located. As a result, the position of the GARS can be elevated and directed by an official at the level of vice-minister right under a president as a governmental representative of managing the public records. In this manner, GARS can sustain its independency and take custody of public records across government agencies. made efforts in regard to the preservation of paper records, the preservation of digital resources in new media formats, facilities and equipments, education of archivists and continuing, training of practitioners, and policy-making of records preservation. For further development, academia and corporate should cooperate continuously to face with the current problems. has held three international conferences to date. The topics of conferences include respectively: 1) records management and archival education of Korea, Japan, and China; 2) knowledge management and metadata for the fulfillment of archives and information science; and 3) electronic records management and preservation with the understanding of ongoing archival research in the States, Europe, and Asia. The Society continues to play a leading role in both of theory and practice for the development of archival science in Korea. It should also suggest an educational model of archival curricula that fits into the Korean context. The Journals of Records Management & Archives Society of Korea have been published on the six major topics to date. Findings suggest that "Special Archives" on regional or topical collections are desirable because it can house subject holdings on specialty or particular figures in that region. In addition, archival education at the undergraduate level is more desirable for Korean situations where practitioners are strongly needed and professionals with master degrees go to manager positions. Departments of Library and Information Science in universities, therefore, are needed to open archival science major or track at the undergraduate level in order to meet current market demands. The qualification of professional archivists should be moderate as well.

• Journal of the Korean Geotechnical Society
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• v.34 no.2
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• pp.33-42
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• 2018

In this study, the EMI (electro-mechanical impedance) of a small piezoelectric sensor was applied for measuring a unit weight and cementation (strength) of sand. Three different sizes of uncemented Nakdong River sand were filled loosely or densely into a compaction mold. A piezoelectric sensor with 20 mm in diameter was installed within sand for impedance measurement. A small Nakdong River sand was mixed with cement ratios of 4, 8 12, 16% and then compacted into a specimen with 50 mm in diameter and 100 mm in height. The specimen consisted of 6 layers with a sensor at the third layer. The impedance signals for 3 days and unconfined compressive strength at the 3rd day were measured. As the unit weight of uncemented sand increased, the resonant frequency increased slightly from 102 to 105 kHz but a conductance at resonant frequency decreased. For cemented sands, as the curing time and cement ratio increased, the resonant frequency increased significantly from 129 to 266 kHz but the conductance at resonant frequency decreased. The unconfined compressive strength (UCS) of cemented sands was between 289 and 1,390 kPa for different cement ratios. The relationship of UCS and resonant frequency linearly increased but one with a conductance at resonant frequency was in inverse proportion.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.83-91
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• 2006

Recently, the intensive rainstorm possibly induced by global warming plays a key role on the instability of railway adjacent slopes. The instability of slopes results as covering and loss of railway lines induced by slided soil mass. According to the site investigation on the failed slopes triggered by rainfall, low types of slope failure were observed: shallow, intermediate, gully erosion, and soil-rock interface failures. The observation reveals the different characteristics of slope failure depending on the thickness of soil layer, morphological features of slope, etc. Based upon the observations, flume tests were conducted to analyze the sliding mechanism of each failure. The variables of flume test are soil layer thickness, rainfall intensity, and morphology of slope under the constant condition of the percentage of fine, initial soil moisture content, slope angle and compaction energy. Test results show that shallow failure was mostly observed from the surface of the slope and caused by the soil erosion; in addition, compared to the other types of failure, the occurrence of initial erosion is late, however, the development of erosion is fast. In gully erosion failure, the collected water from the water catchment area helps erosion of the upper soil layer and transfer of residual corestone, which impedes the erosion process once the upper soil layers are eroded and corestone are exposed. The soil-rock interface failure shows the most fast initial erosion process among the failure types. Interestingly, the common feature observed from the different types of failure was the occurrence of the initial deformation near the toe of slopes which implies the existence of surbsurface flow along the downslope direction.