• Journal of Korean Society of Steel Construction
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• v.19 no.2
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• pp.147-160
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• 2007

In this paper, we described the aeroelastic full-bridge model tests that were conducted to investigate the effect of alternative temporary stabilizing measures for thecable-stayed bridge during construction to ensure aerodynamic stability in the event of a typhoon or similar disasters. The effect of alternative temporary stabilizing measures was investigated through various configurations on two cable-stayed bridges with a main span of 475 m and 230 m, respectively. To investigate the bridge's aerodynamic behaviour and dynamic wind force during construction, the deflections at the end of the cantilever, the accelerations atthe top of the pylon and the moments at the lower part of the pylon were measured. As the result, the system with two sets of vertical cables per cantilever seemed to be the overall most effective solution, but the system with single vertical cable may also work. The combined system using the caisson support and vertical cables and the system with two sets of inclined cables per cantilever on the same anchor block may also be a solution. The inclined cables from the caisson to the girder were effective for some early stages of erecting the deck.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.91-96
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• 2008

In this paper, a monopulse fled for three mode $2{\times}2$ array feed horn antenna was designed. Gain of single feed was 8.25dB. Increasing property of gain and rectangular waveguide and reflection of free space is decreased because it has structure extending to electric plane at connected part from transformation to free space. When fled port1 and port2 is placed vertically and thickness of aperture hem is reduced, isolation is satisfied with property of lower -25dB. Also, at higher frequency, it is confirmed that isolation is improved. Combination of electric field occurs less influence because port1 and port3 is placed horizontally and distribution of electric field is connected to parallel. However, because of combination of electric field, it is more improved from 2dB to 6dB than isolation of port1 and port2. Direct combination occult less effect at port1 and port4 than effect of port2 and port3, it is lower -35dB.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.2
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• pp.61-72
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• 1997

With increasing activities for groundwater withdrawal and for the construction of underground cavern in the coastal areas, the seaward flow of groundwater has been disturbed or even reversed, resulting in seawater intrusion in aquifers. This phenomenon would be attributed to the freshwater contamination and the corrosion of steel materials. The hydrogeological and geochemical investigations have performed to characterize the seawater intrusion into the underground caverns located in the coastal area. Assumimg the inland aquifer as unconfined one, we have found out that the theoretical interface of freshwater-seawater is far different from the pathways identified. In the study site, the main pathways of seawater intrusion into the underground cavern are characterized as the sub-horizontal fractures (zones). The seawater intrusion in granitic terrane would depend mainly on the characteristics of conductive fracture system developed along the coastal area.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.305-330
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• 2023

Unlike NATM tunnels, Shield TBM tunnels have split linings. Therefore, the stress distribution of the lining is different even if the lining is under the same load. Representative methods for analyzing the stress generated in lining in Shield TBM tunnels include Non-joint Mode that does not consider connections and a 2-ring beam-spring model that considers ring-to-ring joints and segment connections. This study is an analysis method by Break-joint Mode. However, we do not consider the structural role of segment lining connections. The effectiveness of the modeling is verified by analyzing behavioral characteristics against vibration loads by modeling with segment connection interfaces to which vertical stiffness and shear stiffness, which are friction components, are applied. Unlike the Non-joint mode, where the greatest stress occurs on the crown for static loads such as earth pressure, the stress distribution caused by contact between segment lining and friction stiffness produced the smallest stress in the crown key segment where segment connections were concentrated. The stress distribution was clearly distinguished based on segment connections. The results of static analysis by earth pressure, etc., produced up to seven times the stress generated in Non-joint mode compared to the stress generated by Break-joint Mode. This result is consistent with the stress distribution pattern of the 2-ring beam-spring model. However, as for the stress value for the train vibration load, the stress of Break-joint Mode was greater than that of Non-joint mode. This is a different result from the static mechanics concept that a segment ring consisting of a combination of short members is integrated in the circumferential direction, resulting in a smaller stress than Non-joint mode with a relatively longer member length.

• Journal of Advanced Navigation Technology
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• v.28 no.3
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• pp.288-299
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• 2024

Indonesia's Keplauan Liau region is facing limitations in the development of connected transportation infrastructure due to its archipelago nature, budget constraints, and lack of land. Transportation demand is increasing due to its strategic location in the Malacca Strait Business Triangle and many tourist visits from Singapore and Malaysia. However, due to the nature of connecting many islands, the establishment of transportation infrastructure has not been achieved. This paper aims to predict the innovations that can be brought about by the introduction of advanced air mobility (AAM) with an electric vertical take-off and landing (e-VTOL) system through analysis and application consideration of the actual situation in Indonesia's Kepulauan Liau region. In addition, it intends to contribute to national-level review and policy establishment on the establishment of innovative transportation infrastructure using AAM, reflection in infrastructure construction plans, and active global cooperation.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.153-153
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• 2011

현대 건축은 기능적이고 합리적이었지만 획일적이었던 박스형 건축에서 탈피해 형태와 공간에 있어서 다양한 변화를 시도하고 있다. 특별한 건축물의 실현을 위해 각 나라의 기술력은 급속한 발전을 이루었고, 보다 더 독특한 건축물에 대한 관심은 비정형 건축물에 대한 관심의 증대로 이어지고 있다. 이러한 비정형 건축물에 적합한 구조로써 프리폼(Free-Form) 구조가 있다. 프리폼 구조로 입체골조(Double Layered Structure)를 많이 사용하였으나, 최근 유리로 되어 투명하고 기하학적 모양의 건축물을 추구함에 따라 평면골조(Single Layered Structure)가 증가하고 있는 추세이다. 평면골조는 축력 지배형과 모멘트 지배형으로 분류할 수 있고 프리폼 구조의 구성 요소 중 가장 취약하고 중요한 부분은 노드이다. 본 연구에서는 프리폼 구조 중 가장 큰 관심이 고조되고 있는 평면골조 모멘트 지배형의 노드에 대한 국내외 기술 분석을 통해 향후 연구 방향성을 제시하고자 한다. 입체골조는 하나의 노드에 여러개의 부재가 3차원으로 결합되어야 하기 때문에 다른 골조 시스템에 비해 노드부가 복잡하지만, 건축물의 외관을 유리로 하여 투명하게 하고 비틀리고 구부러진 구조물에 대한 건축적 요구가 많아짐에 따라 평면골조의 인기가 높아지고 있다. 이러한 시대의 흐름에 발맞추어 건물의 구조적, 기하학적 요구를 충족시키기 위해 다양한 노드 시스템이 개발 중이며, 가해지는 하중의 특성에 따라 축력 지배형과 모멘트 지배형으로 구분하여 노드의 양상을 분류할 수 있다. 축력 지배형의 대표적인 시스템은 다이아그리드(Diagrid)이다. 축력 지배형 프리폼 구조의 노드는 전체 구조물의 하중을 축력으로 받아 모두 전달해야 하기 때문에 크기가 크고 가새가 2~4개층에 걸쳐서 설치되기 때문에 중량이다. 모멘트 지배형 노드를 갖는 프리폼 구조의 형태는 대부분 지붕 구조로써 지붕 자체의 하중만을 견디도록 설계된다. 따라서 노드부와 노드에 붙는 부재들이 가볍기 때문에 사람이 들 수 있고 노드의 크기가 작아 시공성이 좋으며 대량 생산이 가능하다는 장점이 있다. 노드의 형태는 힘의 흐름과 쓰임에 따라 다양하다. 평면골조 모멘트 지배형의 노드는 접합방식에 따라 Splice node connection과 End-Face node connection 두 가지로 분류할 수 있다. Splice node connection은 각 부재의 종축으로 노드와 구조부재 사이에 이음재를 두어 연결하고, 연결 형태에 따라 전단력을 전달할 수 있는 1~2개의 접촉면이 생긴다. 전단응력을 받는 볼트로 이음재를 이어 조립하거나 용접으로 접합할 수 있다. 대표 노드로, SBP-1, SBP-2와 POLO-1 등이 있다. End-Face node connection은 각 연결된 부재의 단부와 노드 사이의 연결면은 종축방향의 수직이고, 인장응력을 받는 볼트를 사용하거나 용접에 의해 접합할 수 있다. 대표 노드로 SBP-4, WABI-1, MERO-1(Cylinder), MERO-2(Block), MERO-4(Double Dish) 등이 있다. 본 기술 현황 분석을 통해 현재 개발된 노드를 분류하고 가장 관심이 높은 Single Layer 모멘트 지배형 노드를 비교, 분석하였다. 최근 건물의 경향을 반영한 프리폼 구조를 실현하기 위해서 필수적인 노드의 개발은 국외에서 활발히 연구되고 있지만 그 기술이 개방되어 있지 않다. 국내에서는 동대문 디자인 플라자에 새로운 노드를 적용하고 고려대학교에서 모멘트 지배형 노드를 개발하는 등 발전 가능성을 보이고 있지만 국외 사례들에 비하면 아직 초기 단계라 할 수 있다. 따라서 현장 용접을 지양하고 공장 제작하여 현장에서 조립하며, 프로젝트 별로 상이한 노드를 사용하는 것이 아닌 다양한 요구를 효과적으로 수용하는 구조 효율성을 향상시킨 노드 상세의 개발이 이루어져야 할 것이다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.4
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• pp.525-535
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• 1999

In this study, a new method of fabricated concrete deck bridge construction is proposed. This paper details the method in which concrete multi-girders and fabricated concrete decks are rested on the upper flange of the girder and the female to female type sheat-key is formed to connect girder and deck. The finite element analysis is performed to verify the accuracy of the structural behaviors of the fabricated concrete deck bridge by comparing with experimental results. The first task performed is the analysis of the equilibrium of the member force occurring between the deck and the girder. After verifying equilibrium of the member force determined by the finite element analysis, this process is applied to the analysis of maximum member force as the position of design load. This task is utilized to determine the safety of each member according to the same scale finite element model. The final process in this study is to compare the deflection of girders used in experiment with that of the same scale finite element model to verify the strength of fabricated cincrete deck bridge. By this comparison, it is shown that the behavior of the fabricated concrete deck bridge is almost same as the finite element analysis. The second task is to analyze the load distribution effect according to the number of diaphragms and the composite effect due to the cinnection of the deck and girder by the finite element analysis. From the results of second task, it is found that the load distribution effect is not related to the number of diaphragms in case of the central loading, but is related to the number of diaphragms for eccentric loading. Analysis of the load distribution indicates that the effective number of diaphragm is three. It is also shown that the maximum deflection is decreased to almost one half due to the composite action of the deck and girder.

• The korean journal of orthodontics
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• v.37 no.4
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• pp.260-271
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• 2007

The purpose of this study was to evaluate the relationships between the occlusal plane angle and craniofacial skeletal pattern in relation to anterior overbite. Methods: Lateral cephalograms of 90 adults with skeletal class III malocclusions were traced and measured to analyze skeletal factors and occlusal plane angles. In terms of anterior overbite, all patients were classified into 3 subgroups of positive overbite, edgebite, and negative overbite groups. All measurements were evaluated statistically by ANOVA and Duncan's Post Hoc, and correlation coefficients were evaluated among measurements. Results: In this study, some skeletal measurements (saddle angle, articular angle, Y axis, AFH, SN-FH, SN-Mn, FH-Mn) showed a significant difference among the 3 groups in relation to overbite changes. Correlation coefficient showed that PFH/AFH, SN-Mn, Mx-Mn, and FH-Mn showed a significant difference with FH-Occ, Mx-Occ, and Mn-Occ. Regression analysis showed that Mx-Mn had a determination coefficient of 0.714, 0.560, and 0.677 in relation to FH-Occ, Mx-Occ, and Mn-Occ, respectively. Conclusion: This study suggests that consideration of the occlusal plane in relation to the maxillomandibular vertical skeletal state enable the establishment of a more predictable orthognathic surgery result.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.351-357
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• 2022

In this study, offshore modular pier system using the ultra-high performance concrete was developed for the offshore construction environment. For the application of offshore modular pier system, the design, fabrication, and construction performance evaluation were performed using ultra-high performance concrete a compressive strength 120 MPa or more and a direct tensile strength 7 MPa or more. For offshore piers previously constructed with precast concrete, it was intended to verify the idea and possibility of solving errors due to position or vertical deformation during the driving of the foundation pile part during the construction stage. Furthermore, a offshore modular pier system was fabricated with ultra-high performance concrete for the construction performance evaluation. The results showed that a offshore modular pier system secured about 9 % of sectional performance of load bearing capacity under ultimate load conditions. If the offshore modular pier system developed through this study is utilized in the future, it is judged that competitiveness due to sufficient durability and constructability can be secured.

• Journal of the Korean Institute of Telematics and Electronics
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• v.5 no.4
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• pp.9-19
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• 1968

In this paper, I introduced the theoretical formulas for calcuating the input impedance of a folded dipole antenna which is held in parallel with the conductive supporter. Through the comparision of the above impedance formulas with the imput impedance formulas of a half wave dipole antenna which is parallel to the conductive supporter, it was found that the former can be made in identically same form as the latter, if some conditions are satisfied. The equivalent conditions mentioned above are derived also and the manufacturing of a vertically polarized omni-drectional antenna is apossible by the use of above equivalent conditions, because a half wave dipole antenna in parallel with a conductive supporter is already illustrated to become an omni-directional vertical polarization antenna. Some experimental data are shown together.