• Title/Summary/Keyword: Architectural Changes

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Conductive Performance of Mortar Containing Fe-Activated Biochar (Fe에 의해 활성화된 목질계 바이오차를 혼입한 모르타르의 전도성능)

  • Jin-Seok Woo;Ai-Hua Jin;Won-Chang Choi;Soo-Yeon Seo;Hyun-Do Yun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.28 no.2
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    • pp.27-34
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    • 2024
  • This study was conducted to examine the feasibility of using Fe-activated wood-derived biochar as a conductive filler for manufacturing cement-based strain sensor. To evaluate the compressive and electrical properties of cement composite with 3% Fe-activated biochar, three cubic specimens of size 50 x 50 x 50mm3 and three prismatic cement-based sensors of size 40 x 40 x 80mm3 were prepared respectively. The four-probe method of electrical resistance measurement was used for cement-based sensors. For cement-based sensors with FE-activated biochar, the conductive performance such as electrical resistance and impedance under different water content and repeated compression was investigated. Results showed that the fractional changes in the DC electrical resistivity of cement-based sensors increase with increasing time and the maximum fractional changes in the resistivity decrease with increasing the moisture contents during 900s. At moisture content of 7.5% range, the conductive performance of cement composite including 3% Fe-activated biochar as a conductive filler showed the most stable, while the strain detection ability tended to decrease somewhat as the repeated compressive stress increased between repeated compressive strain and fractional change in resistivity (FCR).

An Effectiveness Analysis of Landscape Management for the Historic and Cultural Environment Preservation Area of the Pungnammun Gate, Jeonju, by Applying 3D Visual Exposure (3차원 시각노출도를 이용한 전주 풍남문 역사문화환경보존지역의 경관 관리 효과 분석)

  • Lee, Jae-Yong
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.36 no.2
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    • pp.30-37
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    • 2018
  • The uniformed regulations for control of the height of buildings owned by individuals to protect landscape of cultural properties are causing serious social conflicts by limiting the development of landowners. It is urgent need of introducing indicators that can resolve such conflicts and evaluate the regulations of buildings, which can satisfy urban development as well as landscape management of cultural properties. Therefore, the purpose of this study is to simulate landscape changes according to the Cultural Heritage Protection Act and National Land Planning and Utilization Act by using Unity3D in the Pungnammun Gate(Treasure No. 308) of Jeonju and its surroundings, where architectural cultural property forms the symbolic landscape of the city. Then some items such as view points, target points were introduced and the quantitative evaluation of landscapes was attempted by applying the indicator of 3D Visual Exposure. As a result, the viewing opportunity and viewing area of Pungnammun Gate were not significantly influenced by changes in landscape according to the two laws. However, the change of the height of buildings by the National Land Planning and Utilization Act, which has the greatest development capacity, confirmed the possibility of weakening the identification of the Pungnammun Gate by increasing 3D Visual Exposure of the background buildings more than two times. Finally, it was confirmed that the skyline of Pungnammun Gate was clearly infringed upon development under the National Land Planning and Utilization Act, but the skyline was maintained similar to the current situation in the regulation by the Cultural Heritage Protection Act. Thus, this study is meaningful in that the application of 3D Visual Exposure showed the possibility of utilization as an indicator for quantitatively evaluating the protection of view on cultural property and skyline according to the changes of building heights.

The Search for Study on the Construction Process and Changes in the Landscape Plants of the Pasanseodang ('파산서당'의 영건과정과 조경식물 변화상 탐색)

  • Joo, Been;Choi, Hayoung;Shin, Sangsup
    • Korean Journal of Heritage: History & Science
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    • v.51 no.1
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    • pp.48-65
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    • 2018
  • The authors of this paper aim to make a record of the construction process, its symbolic meaning, and the changes in the status of the landscape plants at the Pasanseodang according to the Report on the Pasanseodang written by Park Gyu-hyun in 1874. First, the construction of Samgahun Pavilion, which is located in Myo-ri, Habin-myun, Dalsung-gun, Daegu, took about 90 years and spanned the lifetimes of Park Sungsoo, an 11th-generation descendant of Park Paengnyun (1417~1456) through to Park Kyuhyun, a 14th-generation descendant. It was called the shape of dragon, with its head facing the tail (回龍顧尾形), in feng shui. Second, the village of Pahwoe was founded in 1769, the 45th year of the reign of King Yeongjo, by Park Sungsoo for the purpose of socializing with his friends at his thatched home, and was named after his own courtesy name (Samgahun). Park Kwangseok, the second son of Park Sungsoo, built the sarangchae in 1826 and the anchae in 1869 after his marriage (in 1783). Then, Park Kyuhyun, the grandson of Park Kwangseok, built the pond and planted it with lotus flowers, and built the Hayeopjeong in 1874. The Pasanseodang, as the precursor of the Hayeopjeong, may be related with the name of the hillside region behind Samgahun. Third, a quadrangular-shaped pond with a length of 21m and a width of 15m was also built and planted with lotus flowers. In the center of the pond is a small round island that reflects the world view of the Chosun dynasty, i.e. that the sky is round and the landmass is quadrangular. Meanwhile, the name of the Hayeopjeon reflects the value system of aristocrats who lived a life of leisure and artistic indulgence. They called the eastern room "Yeeyeonhun" (怡燕軒) and the western room "Mongyangjae" (蒙養齋), names which embody their wishes for a good life as a member of the nobility and a bright future for one's descendants. Fourth, in Confucian terms, the authors infer the points of view reflected in the kinds of trees that were planted according to Confucian norms (pine tree, lotus, bamboo), the living philosophy of sustainability (willow), the ideology of seclusion and the search for peace of mind (bamboo), and relief efforts for the poor and a life of practicality (chestnut, oak, wild walnut, lacquer). The authors assert that this way of planting trees was a highly effective design feature of landscape architecture that drew on the locational and symbolic significance of the Seodang. Fifth, the majority of the trees that were initially planted withered and were replaced with different species, except for the locust and lotus, at this point. Nevertheless, a review of the process of construction, symbolic meaning, and original architectural landscape of the Samgahun is of value in demonstrating the extended symbolic meaning of their descendants in terms of the practical loss of the function of the Seodang, the values of Feng Sui (red in the east, white in the west, based on the principles of Feng Sui), the function of repelling evils spirits (kalopanax, trifoliate orange), aesthetic and practical values (sweetbrier, apricot, pear, peach, and oriental oak trees), and the prosperity of the family and the timeless value of honest poverty (silk, crape myrtle, and yew trees).

Characteristics of Shear Strength and Elastic Waves in Artificially Frozen Specimens using Triaxial Compression Tests (삼축압축실험을 이용한 인공동결시료의 강도평가 및 탄성파 특성변화)

  • Kim, JongChan;Lee, Jong-Sub;Hong, Seung-Seo;Lee, Changho
    • The Journal of Engineering Geology
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    • v.24 no.1
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    • pp.111-122
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    • 2014
  • For accurate laboratory evaluations of soil deposits, it is essential that the samples are undisturbed. An artificial ground-freezing system is the one of the most effective methods for obtaining undisturbed samples from sand deposits. The objective of this study is to estimate the shear strengths and the characteristics of elastic waves of frozen-thawed and unfrozen specimens through the undrained triaxial compression test. For the experiments, Jumunjin standard sands are used to prepare frozen and unfrozen specimens with similar relative densities (60% and 80%). The water pluviation method is used to simulate the fully saturated condition under the groundwater table. When thawing the frozen specimens, the temperature is measured every minute. After the specimens are completely thawed, undrained triaxial compression tests are conducted using the same procedures as for the unfrozen specimens. During the triaxial tests (saturation, consolidation, and shear phase), compressional and shear waves are measured. The results show that the freeze-thaw process has minor effects on the peak deviatoric stress and shear strength values, and that the process does not affect the internal friction angle. The compressional wave velocity increases with increasing B-value to 1800 m/s in the saturation phase, but tends to remain constant in the process of consolidation and shearing. The shear wave velocity decreases with increasing B-value in the process of saturation, but changes velocity in accordance with the change in effective stress in the processes of consolidation and shearing. The compressional wave velocity has similar values regardless of the freeze-thaw process, but values of shear wave velocity are slighly lower in frozen-thawed specimens than in unfrozen specimens. This study is a preliminary experiment for estimating the shear strength and characteristics of elastic wave velocity in undisturbed frozen specimens that have been obtained using the artificial ground-freezing method.

The Contents of Namsan Park Records at the Seoul Metropolitan Archives (서울기록원 소장 남산공원 기록물의 현황과 내용)

  • Kim, Jung-Hwa;Gil, Jihye;Seo, Young-Ai;Park, Hee-Soung;Choi, Hyeyoung;Lee, Myeong-Jun
    • Journal of the Korean Institute of Landscape Architecture
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    • v.50 no.6
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    • pp.110-123
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    • 2022
  • Namsan Park in Seoul was designated as a "grand park" in 1954 and is currently operated as an 'Urban Nature Park Area' and four 'neighborhood parks.' However, despite the park's historical and cultural value as an urban park, it has been discussed mainly from a perspective revolving around notions of a mountain or a city wall. To ensure a comprehensive exploration of Namsan Park's history, this study examined public records at the Seoul Metropolitan Archives (SMA), which houses the city's permanent records for preservation and organization. To this end, documents in the SMA Database (DB) were analyzed, yielding 1,359 records concerning Namsan Park. Based on the contents, general characteristics of the urban park were identified through production periods, record types, and disclosure types. Then, essential keywords concerning organizations, people, geographical areas, subjects, and business functions were examined. Finally, the contents and characteristics of Namsan Park in public records were scrutinized, focusing on specific spaces. This research also uncovered important information, such as park drawings, photos, planting lists, plant parcel lists, and significant discussions and decisions regarding the operation and management of the park. Although the public records do not contain a comprehensive history of Namsan Park, it was possible to check the primary historical changes and deliberation processes pertaining to the park's history. Therefore, continuous research intended to interpret and describe public records is expected to identify many implications. In addition, because the public records showed heterogeneous characteristics that center on specific periods and events, an essential task is to advance collaboration and networking with various related institutions, designers, researchers, and citizens.

Ultrasonic Pulses Characteristics in Lightweight Fine Aggregate Concrete under Various Load Histories (하중 이력에 따른 경량 잔골재 콘크리트의 초음파 특성)

  • Yoo, Kyung-Suk;Kim, Jee-Sang;Kim, Ik-Beam
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.3
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    • pp.209-216
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    • 2014
  • One of the widely used NDT(Non-destructive techniques) is the ultrasonic pulse velocity (USPV) method, which determines the travel time of the ultrasonic pulse through the tested materials and most studies were focused on the results expressed in time domain. However, the signal of ultrasonic pulse in time domain can be transformed into frequency domain, through Fast fourier transform(FFT) to give more useful informations. This paper shows a comparison of changes in the pulse velocity and frequency domain signals of concrete for various load histories using lightweight fine aggregates. The strength prediction equation for normal concrete using USPV cannot be used to estimate lightweight fine aggregate concrete strength. The signals in frequency domain of ultrasonic pulse of lightweight fine aggregate concrete does not show any significant difference comparing with those of normal concrete. The increases in stress levels of concrete change the pulse velocities and maximum frequencies, however the apparent relationship between themselves can not be found in this experiment.

Calculation Model for Function & Cost Score based on Normalization Method in Design VE (정규화 기법 기반의 설계VE 기능 및 비용 점수 산출 모델)

  • Lee, Jongsik
    • Korean Journal of Construction Engineering and Management
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    • v.16 no.4
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    • pp.98-106
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    • 2015
  • VE aims at reduction in a budget, improvement of function, structural safety and quality security for public construction projects. However, there is possibility for the structural safety and quality security review to be insufficient because related regulations are mostly composed of analysis on economic efficiency of design. In addition, due to the misconception about VE as a cost saving methodology, an alternative is being presented which still focuses mainly on cost saving, but with no objective evaluation of function related to cost. In order to improve this, the government adopted the reduction of life cycle cost and proposal of value improvement, and let people specify the cost and function of the original plan versus the alternative plan, and the value changes between them. However, it is written mainly into practical convenience rather than theoretical basis since a specific way is not suggested. The current method sets a different starting point by applying the attributional difference of function and cost. Furthermore, an evaluation standard for correlating is an important element in rational decision making for assessing and choosing an alternative. This paper analyzes the process and method of function & cost scoring when performing VE and suggests a mathematical normalization model in order to support rational decision making when selecting an optimum plan.

Estimation of the amount of refrigerant in artificial ground freezing for subsea tunnel (해저터널 인공 동결공법에서의 냉매 사용량 산정)

  • Son, Youngjin;Choi, Hangseok;Ko, Tae Young
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.2
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    • pp.255-268
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    • 2018
  • Subsea tunnel can be highly vulnerable to seawater intrusion due to unexpected high-water pressure during construction. An artificial ground freezing (AGF) will be a promising alternative to conventional reinforcement or water-tightening technology under high-water pressure conditions. In this study, the freezing energy and required time was calculated by the theoretical model of the heat flow to estimate the total amount of refrigerant required for the artificial ground freezing. A lab-scale freezing chamber was devised to investigate changes in the thermal and mechanical properties of sandy soil corresponding to the variation of the salinity and water pressure. The freezing time was measured with different conditions during the chamber freezing tests. Its validity was evaluated by comparing the results between the freezing chamber experiment and the numerical analysis. In particular, the freezing time showed no significant difference between the theoretical model and the numerical analysis. The amount of refrigerant for artificial ground freezing was estimated from the numerical analysis and the freezing efficiency obtained from the chamber test. In addition, the energy ratio for maintaining frozen status was calculated by the proposed formula. It is believed that the energy ratio for freezing will depend on the depth of rock cover in the subsea tunnels and the water temperature on the sea floor.

A study on the slip-up speed of a shaft using heating slip form (히팅슬립폼을 적용한 수직구 구조물의 상승속도에 관한 연구)

  • Ko, Eomsik;Lee, Sanghun;Park, Jongpil;Zi, Goangseup;Kim, Changyong
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.6
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    • pp.811-823
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    • 2019
  • Slip form method is applied to many cases of a shaft these days because it is safer, more economical and faster than cast-in-place method. Slip-up height of the method is approximately 2.5 to 4.0 m/day. If the temperature of concrete is outside the range of 10 to 30℃, the effects of changes in strength or elastic characteristics are significant. Therefore, it is difficult for slip-up speed to be higher than 3 m/day during winter construction. In addition, concrete has heat caused by hydration, which causes temperature cracking of hardened concrete. Therefore, temperature control of concrete curing is necessary for the continuous slip-up of slip form. In this study, the rebound hardness, time of ultrasonic waves propagation, heat of hydration, and external temperature are measured by developing heating panels and test devices for the continuous slip-up. Based on this, heating slip form is manufactured; this was applied to "Kimpo sites" and "Sinwol sites". The compared slip-up speed samples were 1.9 m/day or 0.200 m/hr on average at Gimpo sites (08:00~17:30) and 2.0 m/day or 0.210 m/hr at Sinwol sites.

A Proposal of 3D Printing Service Platform for Construction Industry through case analysis (사례 분석을 통한 건설 3D 프린팅 서비스 플랫폼 제안)

  • Kim, Jongsung;Kim, Sun-Kyum;Seo, Myoung-Bae;Kim, Tae-Hoon;Ju, Ki-Beom
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.11
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    • pp.53-61
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    • 2017
  • Recently, there has been an increase in the number of web-based three-dimensional (3D) printing-related service platforms, which allow consumers to collect 3D modeling data, make requests for production, and receive goods through a distribution service using the service platform. The application of 3D printing technology has been expanded to the construction field, yet no guidelines for the related service platform or operation examples can be found. Therefore, the functions of 10 web-based 3D printing service platforms actively used in other industries were investigated and analyzed in this study, and the analysis results were used as a guideline to develop a 3D printing service platform for the construction industry. In addition, the design, construction and distribution services to be equipped with the construction 3D printing service integration platform were presented by creating the driving scenario of the platform. As 3D printing technology develops, the overall construction and architectural paradigms for design, construction and distribution will change. To prepare for such changes and to pioneer the digital construction market in the future, the role of the 3D printing service platform is expected to increase continually.