• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.166-166
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• 2017

금속 재료 중 철강은 기계적 특성이 우수하고 대량생산이 가능하여 선박, 건축, 자동차 등 다양한 분야에 기초재료로써 널리 사용되고 있다. 그러나 스테인리스강 등과 같은 일부 특수한 용도의 강을 제외하고는 부식환경에 취약한 특성을 가지기 때문에 내식성을 향상을 위한 표면처리에 관한 연구가 활발히 진행되고 있다. 가장 일반적으로 습식법(wet process)을 통해 표면상에 아연(Zn)을 도금해 사용하며, 아연이 자체적으로 포함한 희생양극(sacrificial anode) 및 차폐(barrier) 효과가 철강의 부식을 방지하게 된다. 하지만 산업의 고도화에 따라 더욱 가혹해진 노출환경으로 인해 고내식 강재에 대한 수요가 점차 증가하고 있으며, 아연코팅 층의 두께를 증가하여 내식성을 확보하는 방안은 미래 환경 및 자원적인 측면에서 근본적인 해결책으로 제시하기 어려움이 있다. 한편, 건식 프로세스(wet process)로 대별되는 PVD(physical vacuum deposition)에 의해 내식성을 향상시키고자 하는 연구들이 다양하게 진행되고 있다. 이것은 표면에 고순도 양질의 금속 막을 형성시킴으로써 외부환경과의 반응을 효과적으로 제어가 가능하며, 형성된 막은 그 물질의 고유 특성뿐만 아니라 제작 조건에 따른 표면의 기하학적 혹은 결정학적 구조에 의해 크게 영향을 받게 된다. 본 연구에서는 실용금속 중 이온화 경향이 가장 크고 산소와 반응하여 투과성이 작은 산화 피막 형성이 유리한 마그네슘(Mg)을 활용해 표면의 전기화학적 특성을 향상시켰다. 또한 금속 증착 중 진공도조절을 위해 도입되는 불활성 가스로 아르곤(Ar) 및 질소($N_2$)를 사용하여 표면에 형성한 막의 모폴로지 및 결정배향성이 내식성에 미치는 상관관계를 해석하고자 하였다. 실험방법으로 PVD법 중 비교적 간편하고 기초적인 지침을 제시하기 적합할 것으로 고려된 진공증착(vacuum evaporation)법을 이용해 아르곤 및 질소 분위기에서 진공도를 조절하며 용융아연도금상 Mg막을 형성하였다. 제작조건별 막의 기초 특성을 분석하기위해 SEM, EDS, XRD를 이용하였고, 결정배향성(crystal orientation) 분석을 위해 면간격(d-value)과 상대강도(relative intensity)를 확인하였다. 또한 내식성 평가로 염수분무(salt sprat test) 및 양극분극(anode polarization)을 각각 실시하였다. 실험결과에 따르면, Ar 및 $N_2$ 모두에서 가스압이 증가할수록 코팅층의 증착량은 적어지고 입상정(granular structure)의 모폴로지 형성 및 면간격과 상대강도가 증가하는 것이 확인되었다. 또한 쳄버 내 동일 진공도에서, $N_2$ 도입 시 Mg막은 더욱 치밀하고 미세한 입상정의 모폴로지로 형성되며 면간격과 상대강도는 더욱 증가한 것으로 나타났다. 내식성 평가에서 저진공 $N_2$ 조건에서 형성시킨 막이 가장 우수한 내식성이 나타났는데, 이는 상대적으로 불안정하고 반응하기 유리한 입계면적을 많이 포함한 입상정 모폴로지 및 표면에너지가 높은면의 면점유율 증가로 인해 외부환경과의 신속한 반응은 물론 안정적인 피막형성이 용이하였기 때문일 것으로 사료된다. 이상으로 Ar 및 $N_2$ 가스압 조건에 따른 고내식 Mg 막의 유효성을 확인하였고 향후 내식성을 향상시키는 방법으로 응용 가능할 것으로 생각된다.

• Fire Science and Engineering
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• v.28 no.6
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• pp.52-57
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• 2014

The present study suggests the fundamental method for the prediction time of the fire origin by analyzing the combustion phenomenon of inflammable material in the building structure. The heat release rate (HRR) with time variant is evaluated for the interphone as a inflammable material, which is opted from the fire incidents in the stairwell. the fire dynamics simulator (FDS ver. 6.1) is applied in order to analyze the difference of the smoke inflow time to the downstair from the fire event area with various fire pattern. The results show that the maximum inflow time difference for the case of the interphone made from ABS materials is about 4.93 times with the input conditions of heat flux values and the environment in the FDS for the fixed stairwell which composed of total volume $291.3m^3$, floorage $23.3m^2$ and the height of each floor 2.5 m. This research can be practical information for the application method of simulation scheme with experimental data to the fire Identification.

• Journal of Korean Society of Steel Construction
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• v.26 no.4
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• pp.361-373
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• 2014

As the height and beam span of buildings built in the construction market increase, increasingly higher quality is being required of the construction materials. In response to this trend, 800MPa tensile strength class steel was developed in domestic company. Currently, experiments applying flexural member, compression member, and connections are continuously conducted, but a design guideline for high strength steel has yet to be established. Among those construction materials, for the high strength steel beam-to-column connections, the evaluation of implementing ductile connections for the high strength steel beam-to-column connections is producing pessimistic results and the number of related researches is inadequate because of the high yield ratio, which is the characteristic of high strength steel. This study on implementation of ductile connections made of high strength steel was conducted using the connection detail as the variable, for the purpose of enhancing the deformation capacity of high strength steel beam-to-column connections. Cyclic loading test and nonlinear finite element analysis were conducted with full-scale mock-up connection models with the applied connection details. As a result, the structural performance of high-strength steel beam-to-column connection with presented detail was contented with demand of Special Moment Frames of KBC standard.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.4
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• pp.49-63
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• 2010

This study focused on the method of separation - space organization- as one of the architectural methods that is considered by the view point of its location and arrangement of 'Byoul-seo' private garden pavilion in Honam province. As a result, the followings are conclusions; By this study, they can be found in the concept of '居敬窮理', '格物致知'. It is presumed that nature union is archived through the 'yan-sang(玩賞)' which is ultimate state of knowledge that is based on the premises of opened significance in emancipation from narrow view point in the past and cognition of value. Therefore, it is needed to know the unworldly point of space perception about the pavilion territory, furthermore to have conceptual method to distinct pavilion from the world. there are two methods in the distinct concept in this pavilion research: unworldly separation and meditative separation. It is concluded that the specific consideration of the method of separation that is applied in the Byoul-seo pavilion. And it is accomplished by the contemplation of separation method in approach and entrance of direct influence area. they could be 1) cross the hill, 2) cross over a brook, 3) lifted up in the mount, 4) penetrate the forest, and 5) narrow entrance, which could be part of location.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.1
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• pp.67-77
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• 2018

This study investigated the recognition of Koreanesss, preference factors and the difference of recognition from adjacent Chinese and Japanese gardens for foreign visitors of Seoul gardens, a Korean traditional garden located within the Marzahn garden in Berlin, Germany. Overall, the Chinese garden and the Japanese garden were better known to most visitors than the Seoul garden due to their earlier construction. The awareness of the specialty to the Korean garden was at an average level indicating most visitors did not recognize the difference among the traditional gardens constructed from other countries. These less awareness on the Korean garden was because the traditional gardens of the three countries are located adjacent to the park in a continuous landscape with similar plant species created through natural planting techniques. This means the Korean garden is required for considering diversity and representativeness of planting species, uniqueness in space composition and recognition of Korean oriental garden culture in an initial design project stage. Visitors without prior information has better understanding on Korean garden and higher revisit intention resulting in increasing publicity and understanding of Korean traditional garden. Among the preference factors representing Koreaness of the Seoul gardens, the waterfall, stream, pavilion and natural stone within the water landscape were visitors favorite interests due to design concept with a representative Korean stream scenery of Dokrack-dang and Byeolseo garden resulting in differences from the landscape displaying technique for other oriental gardens. These stylistic differences in the dominant landscaping of garden architecture from surrounding the physical environments, the garden displaying technique derived from Korean natural landscape can be recognized as an unique garden element for foreign visitors.

• Journal of the Korean Geotechnical Society
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• v.23 no.7
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• pp.65-76
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• 2007

Recently, there have been many construction projects on soft ground with growth of industry and various construction problems concerning soft soil behavior also have been reported. Especially, foundation piles of abutments and (or) buildings which were constructed on the soft ground have been suffering from a lot of stability problems of inordinary displacement due to lateral flow of soft ground. Although many researches for this phenomena have been carried out, it is still difficult to assess the mechanism of lateral flow on soft ground quantitatively. And reliable design method for judgement of lateral flow occurrence is not established yet. In this study, PNN (probabilistic neural network) and CNN (committee neural network) theories were applied for judgment of lateral flow occurrence based on eat data compiled from Korea and Japan. Predictions of PNN and CNN models for new data which were not used during model development are compared with those predicted by conventional empirical methods. It was found that the developed PNN and CNN models can predict more precise and reliable judgment of lateral flow occurrence than conventional empirical methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2C
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• pp.71-79
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• 2009

This study is to develope the resilient modulus prediction model, which is the function of mean effective principal stress and axial strain, for three types of railroad trackbed materials such as crushed stone, weathered granite soil, and crushed-rock soil mixture. The model consists of the maximum Young's modulus and nonlinear values for higher strain, analogous to dynamic shear modulus. The maximum value is modeled by model parameters, $A_E$ and the power of mean effective principal stress, $n_E$. The nonlinear portion is represented by modified hyperbolic model, with the model parameters of reference strain, ${\varepsilon}_r$ and curvature coefficient, a. To assess the performance of the prediction models proposed herein, the elastic response of a test trackbed near PyeongTaek, Korea, was evaluated using a 3-D elastic multilayer computer program (GEOTRACK). The results were compared with measured elastic vertical displacement during the passages of freight and passenger trains at two locations, whose sub-ballasts were crushed stone and weathered granite soil, respectively. The calculated vertical displacements of the sub-ballasts are within the order of 0.6mm, and agree well with measured values. The prediction models are thus concluded to work properly in the preliminary investigation.

• Korean Journal of Construction Engineering and Management
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• v.1 no.2 s.2
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• pp.98-107
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• 2000

Increased use of computers in AEC (Architecture, Engineering and Construction) has expanded the amount of information gained from CAD (Computer Aided Design), PMIS (Project Management Information System), Structural Analysis Program, and Scheduling Program as well as making it more complex. And the productivity of AEC industry is largely dependent on well management and efficient reuse of this information. Accordingly, such trend incited much research and development on ITC (Information Technology in Construction) and CIC (Computer Integrated Construction) to be conducted. In exemplifying such effort, many researchers studied and researched on IFC (Industry Foundation Classes) since its development by IAI (International Alliance for Interoperability) for the product based information sharing. However, in spite of some valuable outputs, these researches are yet in the preliminary stage and deal mainly with conceptual ideas and trial implementations. Research on unveiling the process of the IFC application development, the core of the Design Information management system, and its applicable plan still need be done. Thus, the purpose of this paper is to determine the technologies needed for Design Information management system using IFC, and to present the key roles and the process of the IFC application development and its applicable plan. This system play a role to integrate the architectural information and the structural information into the product model and to group many each product items with various levels and aspects. To make the process model, we defined two activities, 'Product Modeling', 'Application Development', at the initial level. Then we decomposed the Application Development activity into five activities, 'IFC Schema Compile', 'Class Compile', 'Make Project Database Schema', 'Development of Product Frameworker', 'Make Project Database'. These activities are carried out by C++ Compiler, CAD, ObjectStore, ST-Developer, and ST-ObjectStore. Finally, we proposed the applicable process with six stages, '3D Modeling', 'Creation of Product Information', 'Creation and Update of Database', 'Reformation of Model's Structure with Multiple Hierarchies', 'Integration of Drawings and Specifications', and 'Creation of Quantity Information'. The IFCs, including the other classes which are going to be updated and developed newly on the construction, civil/structure, and facility management, will be used by the experts through the internet distribution technologies including CORBA and DCOM.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.118-135
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• 2020

It is not uncommon in Korea to see the structure and function of a garden remain intact as well as its form. Yi Cheon-bo's Historic House (Gyeonggi-do Cultural Heritage Item No. 55), located in Sang-myeon, Gapyeong-gun, Gyeonggi-do, is considered an example of very valuable garden heritage, although its family history, location, and remaining buildings and natural cultural assets are not fully intact. Along with Yi Cheon-bo's Historic House, this study attempted to explore the possibility of restoration of the forest houses and gardens by highlighting the high value of Yi Cheon-bo's Historic House through research into the typical layout of private households in northern Gyeonggi Province and Gapyeong County, comparative review of aerial photographs from 1954, and interviews with those involved. The results of the study are as follows: In this study, the presence of Banggye-dongmun and Bansukam in the Banggyecheon area, where the location of the garden was well-preserved, was examined across the landscape of the outer garden, while the location of Yi Cheon-bo's Historic House, the appearance of feng shui, and the viewing axis were considered. Also, the appearance of the lost main house was inferred from the arrangement and shape of the Sarangchae and Haengrangchae that remain in the original garden, and the asymmetry of the Sarangchae Numaru and the hapgak shape on the side of the roof. In addition, the three tablets (Pyeonaeks) of Sanggodang (尙古堂), Bangyejeongsa (磻溪精舍), and Okgyeongsanbang (玉聲山房) were used to infer the landscape, use, and symbolism of the men's quarters. Also, a survey was conducted on the trees that existed or existed in the high prices. Incidentally, it was confirmed that information on boards and cultural properties of Yeonha-ri juniper (Gyeonggi-do Monument No. 61) was recorded to a much lesser extent than the actual required standard, and the juniper trees remaining in the front of Haengrangchae should also be re-evaluated after speculation. On the other hand, as a result of estimating the original shape as a way of pursuing completeness of the garden through restoration of the lost women's quarters and shrine, it is estimated that the main house was placed in the form of a '口' or a 'be warped 口' on the right (north) side of the men's quarters. By synthesizing these results, a restoration alternative for Yi Cheon-bo's Historic House was suggested.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.2
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• pp.37-45
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• 2022

A simplified model using the lifetime distribution has been presented to estimate the Mean Residual Life (MRL) of rubble-mound breakwaters, which is not like a stochastic process model based on time-dependent history data to the cumulative damage progress of rubble-mound breakwaters. The parameters involved in the lifetime distribution can be easily estimated by using the upper and lower limits of lifetime and their likelihood that made a judgement by several experts taking account of the initial design lifetime, the past sequences of loads, and others. The simplified model presented in this paper has been applied to the rubble-mound breakwater with TTP armor layer. Wiener Process (WP)-based stochastic model also has been applied together with Monte-Carlo Simulation (MCS) technique to the breakwater of the same condition having time-dependent cumulative damage to TTP armor layer. From the comparison of lifetime distribution obtained from each models including Mean Time To Failure (MTTF), it has found that the lifetime distributions of rubble-mound breakwater can be very satisfactorily fitted by log-normal distribution for all types of cumulative damage progresses, such as exponential, linear, and logarithmic deterioration which are feasible in the real situations. Finally, the MRL of rubble-mound breakwaters estimated by the simplified model presented in this paper have been compared with those by WP stochastic process. It can be shown that results of the presented simplified model have been identical with those of WP stochastic process until any ages in the range of MTT F regardless of the deterioration types. However, a little of differences have been seen at the ages in the neighborhood of MTTF, specially, for the linear and logarithmic deterioration of cumulative damages. For the accurate estimation of MRL of harbor structures, it may be desirable that the stochastic processes should be used to consider properly time-dependent uncertainties of damage deterioration. Nevertheless, the simplified model presented in this paper can be useful in the building of the MRL-based preventive maintenance planning for several kinds of harbor structures, because of which is not needed time-dependent history data about the damage deterioration of structures as mentioned above.