• Geomechanics and Engineering
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• v.8 no.6
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• pp.859-872
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• 2015

Pebble matrix filtration (PMF) is a water treatment technology that can remove suspended solids in highly turbid surface water during heavy storms. PMF typically uses sand and natural pebbles as filter media. Hand-made clay pebbles (balls) can be used as alternatives to natural pebbles in PMF treatment plants, where natural pebbles are not readily available. Since the high turbidity is a seasonal problem that occurs during heavy rains, the use of newly developed composite clay balls instead of pure clay balls have the advantage of removing other pollutants such as natural organic matter (NOM) during other times. Only the strength properties of composite clay balls are described here as the pollutant removal is beyond the scope of this paper. These new composite clay balls must be able to withstand dead and live loads under dry and saturated conditions in a filter assembly. Absence of a standard ball preparation process and expected strength properties of composite clay balls were the main reasons behind the present study. Five different raw materials from industry wastes: Red Mud (RM), Water Treatment Alum Sludge (S), Shredded Paper (SP), Saw Dust (SD), and Sugar Mulch (SM) were added to common clay brick mix (BM) in different proportions. In an effort to minimize costs, in this study clay balls were fired to $1100^{\circ}C$ at a local brick factory together with their bricks. A comprehensive experimental program was performed to evaluate crushing strength of composite hand-made clay balls, using uniaxial compression test to establish the best material combination on the basis of strength properties for designing sustainable filter media for water treatment plants. Performance at both construction and operating stages were considered by analyzing both strength properties under fully dry conditions and strength degradation after saturation in a water bath. The BM-75% as the main component produced optimum combination in terms of workability and strength. With the material combination of BM-75% and additives-25%, the use of Red Mud and water treatment sludge as additives produced the highest and lowest strength of composite clay balls, with a failure load of 5.4 kN and 1.4 kN respectively. However, this lower value of 1.4 kN is much higher than the effective load on each clay ball of 0.04 kN in a typical filter assembly (safety factor of 35), therefore, can still be used as a suitable filter material for enhanced pollutant removal.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.325-332
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• 2014

Growing concerns about harmful influence of radon on human body, many efforts are being made to decrease indoor radon concentration in advanced countries. To develop an indoor radon reduction technology, it is necessary to develop a technology to predict and evaluate indoor inflow and emission of radon. In line with that, the present study performed computational modelling of indoor dispersion of radon emitted from building materials. The computational model was validated by comparing computational results with analytical results. This study employed CFD (Computational Fluid Dynamics) analysis to evaluate the radon concentration and the airflow characteristics. Air change rate and ventilation condition were changed and several building materials having different radon emission characteristics were considered. From the results, the indoor radon concentration was high at flow recirculation zones and inversely proportional to the air change rate. For the different building materials, the indoor radon concentration was found to be highest in cement bricks, followed by eco-carats and plaster boards in the order. The findings from this study will be used as a method for selecting building materials and predicting and evaluating the amount of indoor radon in order to reduce indoor radon.

• Journal of Conservation Science
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• v.18 s.18
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• pp.19-32
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• 2006

The stone pagoda of the Bunhwangsa temple made by piling small brick-shaped stones. The major rock forming stone bricks are andesites with variable genesis. Rock properties of the pagoda roof stone suffer partly including multiple peel-offs, exfoliation, decomposition like onion peels, cracks forming round lines and falling off stone pieces. The stylobates and tabernacles in all the four directions the pagoda are mostly composed of granitic rocks. Those rock properties are heavily contaminated by lichens and mosses with the often marks of inorganic contamination by secondary hydrates that are dark black or yellowish brown. Within the four tabernacles and northern pagoda body situated to relatively high humidity. There are even light gray precipitate looking like stalactites between the northern and western rocks of the body Their major minerals are calcite, gypsum and clays. The stone lion standing in the southeast and northeast side are alkali granite, while that in the southwest and northwest lithic tuff. Total rock properties of the pagoda are 9,708 pieces, among the all properties, fractured blocks are 11.0%, fall out blocks are 6.7% and covered blocks by precipitates are 7.0%, respectively. The pagoda has highly deteriorated the functions of the rock properties due to physical, chemical and biological weathering, therefore, we suggest that this pagoda has need to do long term monitoring and synthetic conservation researches.

• Journal of architectural history
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• v.11 no.2 s.30
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• pp.37-56
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• 2002

The purpose of this study is to examine the changing process of the collective housing in Korea; focusing on the alteration process of the apartment housing, which became a representative housing type in Korea, nowadays. The alteration process of the apartment housing in Korea can be divided into three stages: the introduction stage, the trial stage and the settled stage. The introduction stage is the period between 1920, when the collective-housing buildings were constructed in Korea for the first time, and the Liberation of Korea(1945). The trial stage is the period between 1945 and 1975. During this period, common housing has been constructed. And the massive apartment buildings were started to be supplied after 1975. The settled stage is the period between 1975 and the present. The main scope of this study will be the introduction and trial stages, since a lot of in-depth studies have been executed on the settled stage. The history of the collective housing of Korea starts with City Housing of Seoul, in 1921. It is guessed that this housing was to be small-sized and row-housing type. The first-built, apartment-type building, in Korea, was Mikuni Apartment House, which was constructed as a boarding room of Mikuni Company. In the introduction stage, apartment buildings were built by Japanese architects, with Japanese housing style. Most of them were planned in dormitory type, and some of them were run as tenant houses. Most of them were constructed by bricks, but sometimes by timbers. Tadami was laid in every room and inside-corridor was located in the middle of the house. Although the major style of the apartment buildings was Japanese, the Korean dwellers of those apartments has been influencing the housing type of them. In the trial stage, apartment housing has been experienced in diverse ways. With the development of building technology, floor heating system was settled in apartment housing. This improved the amenities of apartment dwelling remarkably. Although some heterogeneous characteristics still remained in the apartments of Korea, in terms of housing style, the housing style of apartments has been changed into own style of Korea, in accordance with Korean people's life style. The results of this study give us some good implications regarding contemporary housing plan: First, if the unit size of a collective housing is small, the more space could be available for community activities. Second, when planning of collective housing, more concerns should be payed on surroundings. Third, more attention should be payed about low-rise apartment housing, and more land-friendly planning would be required.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.815-828
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• 2013

Recently internet shopping malls provide newer and more varied goods and services to meet the demand of their customers. And as new companies enter the on-line shopping mall business, competition in this specific market is getting stiffer. Therefore, to keep a more sustained relationship with their customers, internet shopping malls need to satisfy their customers with their goods and services and to make them loyal customers. Unlike bricks-and-mortar stores in real life, This study also aims to propose an on-line physical environment model, and to develop the existing on-line research into a physical environment. The physical environment is measured on the four dimensions and 4 measurement units and the on-line physical environment, trust, and purchasing decisions are also explained. This study makes contributions as follows. First, online physical environments contain theoretical syntheses and operational definition. Second, this study finds that trust is an important part of an on-line transaction. Third, this study provides an insight into some of the factors preceding purchasing decisions. Lastly, this study finds that the consumer's comprehension of the on-line environment has a considerable influence on trust and purchasing decisions.

• Journal of Conservation Science
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• v.27 no.3
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• pp.313-322
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• 2011

The floral wall of Lee Sang-beom's House and Atelier, which is No. 171 of the Registrated Cultural Heritage was conserved. In addition, materials characteristics and manufacturing technique have revealed through the scientific analysis. As a result of the analysis, samples were divided into three sections; the support layer that is made from block bricks, the paint layer and the cement mortar layer on the paint layer for the reinforcement of the construction. The higher layer lies, the finer grains it has. Furthermore, a little it was generated a small quantity of pores and calcium carbonates ($CaCO_3$) generated due to aeration of cement mortar. The patterns of letters, animals and plants pattern were expressed in the paint layer by relief and openwork. The results of qualitative analysis of the pigments of the paint layer were detected components of carbon black (C), Fe oxide ($Fe_2O_3$) and oyster shell white ($CaCO_3$, or quicklime). On the other hands, as the conservation of the floral wall, stainless frames were set up for the structural stability, the cement mortar were removed from the surface and the partly damaged and cracked areas were filled with KSE Filler A, B.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.93-102
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• 2011

In this study, experiments on total digestion and sequential extraction were conducted in order to understand total metal contents, and mobility, bioavaliability and toxicity of metals in marine dredged sediment from Busan New Port. The total concentrations of arsenic and heavy metals in the dredged sediment were relatively low as follows: Al (2.36~2.96 wt.%), As (1.6~3.3 mg/kg), Ba (30.0~33.8 mg/kg), Cd (0.12~0.18 mg/kg), Cr (27.5~35.0 mg/kg), Cu (11.3~15.0 mg/kg), Fe (2.91~3.51 wt.%), Mn (324~408 mg/kg), Ni (18.8~23.8 mg/kg), Pb (23.8~31.3 mg/kg), and Zn (70.0~86.3 mg/kg). In addition, it was found that most of Al (87.5~95.9%), As (74.1~93.8%), Ba (71.8~77.6%), Cr (69.5~94.3%), Cu (50.0~78.7%), Fe (70.8~87.6%), Ni (64.5~75.3%), Pb (53.4~64.3%), and Zn (62.5~81.7%) existed in the residual fraction, meaning that those elements might come from natural sources. On the other hand, Cd and Mn were present mainly in the non-residual fraction. Due to low concentrations of toxic heavy metals and high percentage of residual fraction, it could be possible to reuse the dredged sediment for bricks, pavement base material, etc.

• Journal of the Mineralogical Society of Korea
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• v.31 no.3
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• pp.149-159
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• 2018

The Gyeongju Bunhwangsa Stone Brick Pagoda, which was built with bricks of andesite, is the oldest brick stone pagoda of Silla period. The damage patterns in the stone pagoda are pollutants such as white crust, black crust, discoloration, soil adsorption, and microorganisms, and repair materials. The damage pattern of structural factors in the Stone Brick Pagoda is a bulging phenomenon. According to the X-ray diffraction analysis, white crust are mainly consist of calcite ($CaCO_3$) and thermonatrite ($Na_2CO_3{\cdot}H_2O$) that evaporite finds in nature. Damage pattern varies depending on location of stone pagoda. The pollutants are first story body of pagoda. The microorganisms are confirmed at base, lion statues, first and second story capstone, and repair materials observed at base. The bulging phenomenon appeared on the first story body of the pagoda. Occupancy rates by damage type were higher in the order of microorganisms, pollutants, repair material, bulging phenomenon, and peeling. The highest percentage of individual damage patterns were black microorganisms (39.3%), followed by lichen (17.9%), discoloration (8.0%), white crust (5.5%), cement mortar (5.1%) and peeling (3.1%).

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.114-118
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• 2009

With the advance of industrialization and urbanization, a lot of waste has been discharged and treated by incineration. But fly and bottom ashes are generated in this process. In addition, the treatment method to recycle sewage sludge and melting slag is required to manage these wastes. The objective of this research was to prepare of multi-functional brick which were made from MSWI (Municipal solid wastes incinerator) fly ash, sewage sludge and slag. The bricks were made by mixing raw materials and then drying for 24 hours. Next, they were dried for 24 hours at $160^{\circ}C$ and fired for 2 hours. Calcination temperature was changed to discuss the effect of temperature from $1,080^{\circ}C$ to $1,130^{\circ}C$. Compressive strength of a brick was creased with the increase of temperature. To increase mixing ratio of fly ash and slag reduce the compressive strength the optimal condition was the mixing ratio of fly ash : melting slag : sewage sludge : clay as 10 : 20 : 5 : 65 and $1,150^{\circ}C$ of calcination temperature. Compressive strength was obtained as about 41 MPa at this condition.

• Korean Journal of Environment and Ecology
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• v.31 no.1
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• pp.24-29
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• 2017

This study was conducted to identify nesting habits and breeding biology of barn swallow in Gwangju, Korea, for the breeding season 2012 to 2014. All nests were attached to vertical walls and roofs of buildings and situated at mean height $2.9{\pm}0.3m$ above ground with nest diameter $18.2{\pm}3.2cm$, nest depth $9.8{\pm}3.1cm$, nest cup diameter $11.2{\pm}1.5cm$ and nest cup depth $3.27{\pm}0.80cm$. Nests were attached to cemented walls (44.9%), wooden materials (23.1%), bricks (21.8%) and lighting (6.4%). The average clutch size was 4.5 and ranged 2~5. Mean egg length was $18.23{\pm}0.73mm$, breadth $13.11{\pm}0.25mm$, volume $1.60{\pm}0.11cm^3$, shape index $1.39{\pm}0.05$ and weight $1.69{\pm}0.15g$. Hatching and fledgling success rate were 89.1% and 84.5%. Main causes for reproductive failures were unhatched eggs, predation, nest destruction and desertion. These results are expected to be widely used as data for habitat preservation and species management of barn swallows.