• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.29-32
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• 2009

Building foundations for Top-Down construction require a special setting, because the foundations have to be placed way before excavation for the substructure of main building, Usually, the foundation goes into the layer of rock and it is often called rock-pier foundation, Currently, a cage of steel reinforcing bars is inserted to the pre-excavated hole in the rock layer, hanging down from the wide flange steel column above. This paper presents a new method for connecting the prefounded column and the steel cage with a coupler for better connection between the two, The use of a circular Concrete Filled Tube (CFT) as a prefounded column makes it possible to have this type of connection. The details of the connection and application to a Top-Down construction site is also included in this paper.

• Journal of the Korean Society of Safety
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• v.37 no.3
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• pp.79-85
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• 2022

The annual statistics on fall fatality consistently show the dangers of working at height. The "Occupational Safety and Health Act" specifies legal restrictions on work at height using a scaffold. However, there are different classes of work at height, and some rely only on ropes. This study proposes education, training, and institutionalization of the "rope access work system." In brief, it was concluded that accurate instruction on the knot method and the setting of some standards were important. For this, the use of an integrated work chair harness equipment was suggested.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.25-32
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• 2021

Geotextile tube technology has been perceived as an economical solution for liquid sludge treatment, and analyzing its consolidation behavior is necessary to be able to evaluate the dewatering capabilities of large geotextile tubes filled with contaminated soil, tailings, sewage sludge, and so on. The objectives of this study are to present a method that can adequately convey the consolidation behavior of geotextile tubes filled with sewage sludge, and to investigate the effects of various geotextile tube consolidation parameters. In this study, variable coefficients of consolidation are utilized to analyze the consolidation process of geotextile tubes filled with sewage sludge. The consolidation solution was verified by comparing the measured and predicted data from a hanging bag test conducted in the literature. After verifying the proposed solution, the consolidation parameters of a geotextile tube composed of a woven polypropylene outer layer and a non-woven polypropylene layer filled sewage sludge were obtained. Using the obtained parameters, the consolidation behavior of a large-scale composite geotextiles tube was predicted.

• Korean Journal of Heritage: History & Science
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• v.55 no.2
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• pp.24-48
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• 2022

Bronze mirrors found in pagodas were regarded as simple offerings and thus have received little attention in studies. Furthermore, the few studies on bronze mirrors enshrined in pagodas have focused on the line-engraved mirrors found in the pagodas of the Kingdom of Wuyue; therefore, it is difficult to understand the general characteristics of the bronze mirrors enshrined in the pagodas. This study assumes that the bronze mirrors found in many pagodas in the Kingdom of Wuyue and the Song dynasty were enshrined for a specific purpose. To explore this assumption and accurately understand the artifacts, this study focuses on the location and method of enshrinement. The number of bronze mirrors enshrined in pagodas increased during the Kingdom of Wuyue, with the mirrors expressing statues and inscriptions related to Buddhism rather than being simple offerings. This shows that the purpose of the bronze mirror changed. The influence of the Kingdom of Wuyue continued during the Song dynasty; however, the pattern of bronze mirror enshrinement changed due to the culture and social atmosphere of the time. The most common types of enshrined bronze mirrors were plain, and bronze mirrors from the Dang dynasty were also used consistently. Plain bronze mirrors were used more frequently in this period despite the lingering influence of the Kingdom of Wuyue because it was less laborious to engrave images and inscriptions such as the inscription of Buddha. Additionally, bronze mirrors were valued during this period because of the attention toward the imitation of the archaic bronze(仿古銅器) of the Song dynasty and the influence of the emperor. Moreover, it is believed that bronze mirrors were enshrined in pagodas as offerings as they were deemed valuable at the time. There was a change in the method of enshrining bronze mirrors in pagodas during the Kingdom of Wuyue and the Song dynasty. During this time, bronze mirrors that were positioned on the floor or in iron boxes were intentionally attached to walls or hung from the ceiling. This method was largely divided into two types: attaching to walls or the ceiling(嵌入鏡) and hanging from the ceiling(懸鏡). A typical example of hanging a bronze mirror from the ceiling can be seen in the Jingzhisa Temple Pagoda, and Teng County's Fushengsa Temple Pagoda contains an example of attaching a bronze mirror to the ceiling. The methods of hanging or attaching bronze mirrors to the ceiling were closely related to the methods employed in Chinese tombs. Song dynasty burial chambers had a high and wide structure, so to defend against evil spirits(辟邪用), bronze mirrors were used to protect the burial rooms. Bronze mirrors were, therefore, placed high to illuminate the burial room. This was achieved in the ways mentioned above. As underground chambers became wider and higher, mirrors also protected the important areas of the chambers and illuminated the interiors. Thus, it is believed that the methods of enshrining bronze mirrors in the pagodas during the Kingdom of Wuyue and the Song dynasty arose from the method of enshrining bronze mirrors in tombs at the time. Thereafter, pagodas, such as the Miaojuesa Temple Pagoda, in which the placement of a bronze mirror was actively considered from the design stage were constructed.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.568-573
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• 2013

A selective and sensitive method for simultaneous determination of copper in blood by adsorptive differential pulse cathodic stripping voltammetry is presented. The procedure involves an adsorptive accumulation of Cu(II)-ETSC (4- ethyl-3-thiosemicarbazide) on a hanging mercury drop electrode, followed by a stripping voltammetry measurement of reduction current of adsorbed complex at about -715 mV. The optimum conditions for the analysis of copper (II) ion are : pH 10.3, concentration of 4-ethyl-3-thiosemicarbazide $3.25{\times}10^{-6}$ M and an accumulation potential of -100 mV. The peak current is proportional to the concentration of copper over the range 0.003-125 ng/mL with a detection limit of 0.001 ng/mL and an accumulation time of 60 s. Moreover, with the use of the proposed method, there is a considerable improvement in the detection limit, the linear dynamic range and the deposition time, compared with the methods of adsorptive stripping voltammetry for the determination of copper. The developed method was validated by analysis of whole blood certified reference materials.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.788-793
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• 2009

Constructing substructures by using Top-Down or Downward method needs an efficient formwork system because of difficulties in supporting concrete slabs from the bottom while excavation is in process. Existing underground formwork systems can be classified by three types: graded ground supported type (Slab On Grade, Beam On Grade), suspension type (Non Supporting Top Down Method), and bracket supported type (Bracket Supported R/C Downward). Each method has its own advantages and limits. Application of a specific formwork system for a given construction site is determined by various conditions and affect construction time and cost. This paper presents a newly developed underground non-supporting formwork system, which combines the advantages of a suspension type and a bracket supported type while it overcomes limits of two types. The developed system has a moving formwork which is supported by suspension cables hanging from the bracket placed at the top of pre-installed substructure columns. Then, the moving formwork is repeatedly lowered down for the next floor below to support concrete slab during curing. The details of this bracket and cable supported system have been investigated for the improvement of easiness in construction.

• Journal of the Korean Wood Science and Technology
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• v.51 no.6
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• pp.509-525
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• 2023

This study has delved into the evolution of Hanji-manufacturing molds and techniques from ancient times to the present, aiming to uncover the current state of traditional Hanji-making techniques. In the absence of records on Hanji-making, various ancient documents, rare books, and documents during the Japanese occupation period, among other artifacts and relics, were analyzed in this study. It was discovered that a sudden significant transformation occurred in the Hanji field during the Japanese occupation period. Soda ash and caustic soda were commonly used for the pretreatment of White bark. Furthermore, a chemical bleaching powder was introduced for the pretreated White bark. Additionally, manual beating of the bark was replaced by mechanical beating methods. While these changes brought convenience to papermakers, they also resulted in a deterioration of Hanji quality. Furthermore, it was revealed that the term "Hanji" has been in use since at least 1908. Furthermore, this study clarified that Heulimtteugi is not the only traditional Hanji-making method in Korea. Instead, there existed Korea's own traditional Gadoomtteugi method, at least up to the 1930s, before the Japanese-style Gadoomtteugi became common in Korea. Additionally, for the first time, this study raises the possibility of the adoption of mold-hanging techniques into Korea's Heulimtteugi method from foreign sources.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.2
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• pp.132-142
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• 2017

As the International Maritime Organization (IMO) recently introduced the Energy Efficiency Design Index (EEDI) for new ships building and the Energy Efficiency Operational Indicator (EEOI) for ship operation, thus an accurate estimation of added resistance of ships advancing in waves has become necessary. In the present study, OpenFOAM, computational fluid dynamics libraries of which source codes are opened to the public, was used to calculate the added resistance and motions of the KCS. Unstructured grid using a hanging-node and cut-cell method was used to generate dense grid around a wave and KCS. A dynamic deformation mesh method was used to consider the motions of the KCS. Five wavelengths from a short wavelength (${\lambda}/LPP=0.65$) to a long wavelength (${\lambda}/LPP=1.95$) were considered. The added resistance and the heave & pitch motions calculated for various waves were compared with the results of model experiments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.135-136
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• 2022

Defects caused by apartment houses have the term of warranty liability according to the enforcement ordinance of Acts of the Management of Apartment Houses. In case when defects occur during the term, free defect maintenance can be provided from the construction company. Yet, there occur conflicts between the construction company and residents, as to whether there occur defects or not. To resolve these conflicts, this study aimed to analyze construction classification and types that need managing, based on defects of apartment houses occurring during the term of warranty liability. This research analyzed 138,576 cases of data, as of five apartment house complexes. For the construction classification for defects of apartment houses, wooden flooring products accounted for the highest rate, followed by paper hanging, and wooden window. For the construction types of defects, torn/scratching took up with the highest rate, followed by the condition of defect in fixing and operating. In order to embody defects occurring during the term of warranty liability, into the visualization technique, this researcher utilized the word cloud method. This study will pursue the method for maintaining defects during the term of warranty liability, in the subsequent research, using the data that this research presented.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.749-765
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• 2021

Suspension bridges bear large eccentric live loads in rush hours when most vehicles travel in one direction on the left or right side of the bridge. With the increasing number and weight of vehicles and the girder widening, the eccentric live load effect on the bridge behavior, including bending and distortion of the main girder, gets more pronounced, even jeopardizing bridge safety. This study proposes an analytical algorithm based on multi-catenary theory for predicting the suspension bridge responses to eccentric live load via the nonlinear generalized reduced gradient method. A set of governing equations is derived to solve the following unknown values: the girder rigid-body displacement in the longitudinal direction; the horizontal projection lengths of main cable's segments; the parameters of catenary equations and horizontal forces of the side span cable segments and the leftmost segments of middle span cables; the suspender tensions and the bearing reactions. Then girder's responses, including rigid-body displacement in the longitudinal direction, deflections, and torsion angles; suspenders' responses, including the suspender tensions and the hanging point displacements; main cables' responses, including the horizontal forces of each segment; and the longitudinal displacement of the pylons' tower top under eccentric load can be calculated. The response of an exemplar suspension bridge with three spans of 168, 548, and 168 m is calculated by the proposed analytical method and the finite element method in two eccentric live load cases, and their results prove the former's feasibility. The nonuniform distribution of the live load in the lateral direction is shown to impose a greater threat to suspension bridge safety than that in the longitudinal direction, while some other specific features revealed by the proposed method are discussed in detail.