• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5385-5392
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• 2014

Super typhoons develop as a result of meteorological changes. In 2012, Typhoons Bolaven and Denba reached Korea. The maximum instantaneous wind speed of the typhoons reached 60 m/sec. Harbor structures including sofa block sustained damage and loss by the abnormally high waves. In Korea, tetrapod blocks were installed the most for wave dissipating. Nevertheless, a structural evaluation of the tetrapod block has not been performed. This study examined the structural mechanism and weakness part of the tetrapod block under a range of boundary conditions. The block has weakness against a tensile force because it is plain concrete. The joint part of the legs is the most vulnerable to tensile stress. The weakest part can be reduced if the joint part is reinforced as a hunch.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.1
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• pp.43-50
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• 2004

This study was performed to measure the retentive force of dental impression tray according to retention form. The 9 resin beams($30{\times}60{\times}2.5mm$) were made of visible light-curing tray resin according to the surface texture, the size of hole and the number of rim. The resin block was fabricated in width 50mm, length 30mm, heght 40mm to maintain an even hydrocolloid impression material. The retentive force between the resin beam and hydrocolloid impression material was measured by Universal Testing Machine(Zwick Z020, Zwick Co., Germany). The results obtained in this study were as follows : 1. The retentive force of the resin beam with bilateral 4 rims, 2mm holes(9group) was highest(9.18kg), and the polishing resin beam(2group) was worst(4.85kg). 2. There was no significant difference between the polished the resin beam(2group) and the contrast resin beam(1group). 3. The retentive force of the rimmed resin beam was higher than the perforated resin beam. 4. The retentive force of the 2mm perforated resin beam(4group) was higher than the 3mm perforated resin beam(3group). 5. As increasing the number of rim increased the retentive force.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1502-1508
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• 2011

Ground anchor expands the hollow wall of settled part and has the structure which resists the designed tensile load by the bearing pressure generated by the wedge of the anchor body pressing in the expanded part. Such ground anchor has been recognized for stability and economicality since 1960s in technologically advanced nations such as Japan and Europe, and in 1970s, the Japan Society of Soil Engineering has established and announced the anchor concept map. The ground anchor introduced in Korea, however, has the structural problem where the tensile strength is comes only from the ground frictional force due to expansion of the wedge body. In an interval where the ground strength is locally reduced due to fault, discontinuation or such, this is pointed out as a critical weakness where the anchor body of around 1.0m must resist the tensile load. Also, in the installation of concrete block, the concentrated stress of concrete block constructed on the uneven rock surface causes damage, and many such issues in the anchor head have been reported. Thus, in this study, by using the expanded bit for precise expansion of settled part, the ground anchor system was completed so that the bearing pressure of ground anchor can be expressed as much as possible, and the bearing plate was inserted into the ground to resolve the existing issues of concrete block. Through numerical analysis and pullout test executed for verification of site applicability, the pullout-behavior characteristics of anchor was analyzed.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.48
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• pp.57-76
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• 2010

This study reviews maritime transport policy regarding liner conference and the changes in the liner market over the decades. Liner shipping industry has long been protected from competition by block exemption. To prevent excessive competition in punctual operation and its inelastic market structure, liner shipping companies formed conferences that are protected to fix the prices under the law. In the US, deregulation in transport sector began from 80's and continuing with OSRA 1998, conferences were dissolving. On the other hand, the EU with close conference system, Regulation 4056/86 contained block exemption remained in force for unlimited time without review clause. However, in Oct 2008, the EU has announced its removal, and conferences were no longer permitted to fix the price nor exchange information. Although OSRA 1998 has already broken up conferences by allowing individual service contracts, but the repeal of the immunity for price fixing will alter significantly the rule on cooperation in the industry since it is a unilateral move by the EU, especially in transatlantic lane. There are rapid changes in shipping market getting much more complicated, and with removal of 4056/86 allowing the market to be more competitive, opening up the industry with far more diverse strategic options. Hence this paper reviews on liner shipping industry and its changes of policies over the years from protected market to open competition market of today.

• Structural Engineering and Mechanics
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• v.33 no.5
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• pp.605-619
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• 2009

This paper presents the details of finite element (FE) modeling and analysis of an external prestressing technique to strengthen a prestressed concrete (PSC) end block. Various methods of external prestressing techniques have been discussed. In the proposed technique, transfer of external force is in shear mode on the end block creating a complex stress distribution. The proposed technique is useful when the ends of the PSC girders are not accessible. Finite element modeling issues have been outlined. Brief description about material nonlinearity including key aspects in modeling inelastic behaviour has been provided. Finite element (FE) modeling including material, loading has been explained in depth. FE analysis for linear and nonlinear static analysis has been conducted for varying external loadings. Various responses such as out-of-plane deformation and slip have been computed and compared with the corresponding experimental observations. From the study, it has been observed that the computed slope and slip of the steel bracket under external loading is in good agreement with the corresponding experimental observations.

• The KSFM Journal of Fluid Machinery
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• v.17 no.1
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• pp.41-46
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• 2014

The thermal-flow characteristics of screw compressor were numerically investigated with various geometrical configurations of its coolant flow passage applied to the separate block for enhancing the heat transfer performance of it. The length ratio($L_s/D$=4.8, 5.6, 6.4) and thickness ratio(t/D=0.2, 0.4, 0.6) of the separate block in the flow passage of the water jacket were adopted to design parameters. Results showed that the pressure drop and heat transfer were increased as the length of separate block increases due to the flow separation and centrifugal force. The results were graphically depicted with various flow and geometrical conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.87-96
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• 2010

PAP method is a combined measures which consist a anchored retaining wall method with permanent ground anchors and vertical precast concrete panels, step by step on the slope surface. And soil is back filled between slope and vertical precast panels. Therefore, this method is more effective than any other ground anchor reinforcing methods of slope stability, for example cross type concrete block ground anchor or buttress concrete block ground anchor method. Because of increasing effective anchor force and green tree planting.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.3 s.96
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• pp.346-353
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• 2005

In this paper, the tension of assembly stay cable connected with massive anchorage block was calculated through back analysis of in-situ frequencies measured from a stadium structure. Direct approach to back analysis is adopted using the univariate method among the direct search methods as an optimization technique. The univariate method can search the optimal tension without regard to the initial ones and has a rapid convergence rate. To verify the reliability of back analysis, Tension formulas proposed by Zui et al. and Shimada were used. Tensions estimated by three methods are compared with the design tension, and are in a reasonable agreement with an error of more or less than 15%. Therefore, it is shown that back analysis applied in this paper is appropriate for estimation of cable tension force.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.1068-1073
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• 1987

Traditional circuit partitioning algorithm using the cluster development method, which is suitable for such applications as single chip floor planning or multiple layer PCB system placement, where the clusters are formed so that inter-cluster nets are localized within the I/O connector pins, may not be appropriate for the functiona block placement in truly 3-D electronic modules. 3-D hybrid IC is one such example where the inter-layer routing as well as the intra-layer routing can be maximally incorporated to reduce the overall circuit size, cooling requirements and to improve the speed performance. In this paper, we propose a new algorithm called MBE(Minimum Box Embedding) for the layer assignment of each functional block in 3-D hybrid IC design. The sequence of MBE is as follows` i) force-directed relaxation in 3-D space, ii) exhaustive search for the optimal orientation of the slicing plane and iii) layer assignment. The algorithm is first explaines for a 2-D reduced problem, and then extended for 3-D applications. An example result for a circuit consisting of 80 blocks has been shown.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.211-215
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• 1996

This paper presents comparisons of pullout load of concrete with compressive strength of cylinders and cores, pulse velocity, and rebound number. A pullout test, which is a relatively new nondestructive technique, measures with a special tension ram the force required to pullout a specially shaped steel rod whose enlarged end has been cast into a concrete block. In this study 3 concrete mixes(normal strength, high-strength & super-high-strength) were made. From each mix, one 100$\times$70$\times$20 concrete block, 24 cylinders$(\phi10mm)$were casted. Each tests were performed on the concrete blocks at 3, 7, 28, and 91days. The test data shows that the pullout test is superior to the rebond hammer and the pulse velocity measurements on the evaluation of concrete strength. The pullout test is satisfactory for estimating the strength of in situ concrete at both early and late age, and its results can be reproduced with an acceptable degree of accuracy.