• Journal of Korea Foresty Energy
• /
• v.21 no.2
• /
• pp.62-68
• /
• 2002

Adiabatic property of plywood wall panel was examined to evaluate their thermal conductivities. The amount of heat loss was investigated through overall heat transmission experiment. Styroform and grass wool showed less heat loss. However, yellowsoil board and laminated lumber showed high volume specific heat capacity. When the changes of indoor and outdoor temperature were checked in model house, wall manufactured with styroform and grass wool was affected easily by the changes of outdoor temperature. Yellowsoil, the mixed board of yellowsoil and sawdust, and laminated lumber, which have high volume specific heat capacity, were not affected much. The rates of overall heat transmission were much better in styroform and grasswool, but the adiabatic properties were much higher in yellowsoil board and the mixed board of yellowsoil and sawdust. The results showed that the insulating material can be developed using yellowsoil and wood, which are nature friendly materials.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.31 no.6
• /
• pp.920-926
• /
• 1998

To investigate the effects of yellow loess on the microbial community after applying into C. polykrikoides as a red tide centrol method during decomposition process, we conducted this study using microcosm experiments, which consisted of sediment collected from Jinhae and Masan bay. The composition, number of bacteria and respiratory electron transport system activity (ETSA) were analyzed. The number of heterotrophic bacteria examined in the samples of both stations reached maximum value within 12 hrs with $10^7$ cells/dry g, independent with the yellow loess applied. In addition, a differenee in the variation of heterotrophic bacterial composition was not observed by adding the yellow loess, and Vibrio spp. always appeared during the culture periods, However, in day 8 culture, the sulfate reducing bacteria was $3.8\times10^7$ cells/dry g in Masan bay and $5.5\times10^6$ cells/dry g in Jinhae bay samples without yellow loess, and these were 120, 350 fold-and 160, 420 fold-increased when yellow loess was added (1 : 1, 1 : 2). The average ETSA was 6.8$\~$7.6 $\mu$g formazan $h^{-1}$ dry $g^{-1}$ independently with yellow loess in aerobic condition for both samples, but activity was decreased by addition of yellow loess in anaerobic. Thus the addition of yellow loess to marine sediment seems to have an effect to inhibit the anaerobic decomposition process and growth of sulfate reducing bacteria which lead to the bad condition of marine environments.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.16 no.2
• /
• pp.141-151
• /
• 2010

Harmful algal blooms (HABs), commonly known as red tides, are aquatic phenomena caused by the rapid growth and accumulation of certain microalgae, which can lead to marked discoloration of surface waters, and severe impacts on public health, commerce, and the environment. In South Korea, the red tides have been a serious and recurrent problem, especially along the south coast. Plenty of yellow loess was used to control an outbreak of the red tides for 15 years from 1996 until now. Yellow loess was almost sprayed in the vicinity of a large fish farming industry. In this research, the distribution characteristics and density distribution of zooplankton were investigated in autumn (Oct. 2008) and spring (Apr. 2009) using volume backscattering strength (SV) calculated by the zooplankton collected with north pacific standard (NORPAC) net and the echo intensity measured with ADCP at stations on the study area in the spraying ocean of yellow loess (SOYL), and the non-spraying ocean of yellow ocean (NOYL) by the red tide generating every year. The species number and the individuals per unit volume of the zooplankton collected in NOYL was high and it which was collected in SOYL was low. As a result of comparing the volume backscattering strength ($SV_c$) calculated by species and length of the zooplankton collected with NORPAC net with the volume backscattering strength ($SV_m$) calculated by the echo intensity measured with ADCP at stations on the study area, although $SV_c$ and $SV_m$ of NOYL were generally in agreement, $SV_m$ of SOYL was higher than $SV_c$ 4.3dB, i.e. ADCP is greatly influenced by suspended solid in SOYL. The horizontal distribution map of $SV_m$ at the study area in autumn (Oct. 2008) and spring (Apr. 2009) was drawn. $SV_m$ of SOYL is higher than NOYL and autumn is higher than spring. $SV_m$ can suppress the overestimate or underestimate of $SV_c$.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10b
• /
• pp.247-248
• /
• 2003

최근 환경과 건강에 대한 관심이 증대되면서, 염색 가공분야에 있어서도 환경오염을 일으키지 않으면서도 위생적인 쾌적성을 부여하는 가공이 큰 주목을 받고 있다 이러한 측면에서 황토와 키토산은 두 가지 요구를 모두 충족시킬 수 있는 훌륭한 천연소재이다. 본 연구에서는 황토 염색 전, 후에 키토산을 처리한 면직물을 이용하여, 키토산의 농도와 처리 조건에 따른 항균성 중진효과를 고찰하고자 하였다. (중략)

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.285-286
• /
• 2010

The purpose of this study aimed to evaluate properties of fluidity, compressive strength and bending strength of Loess mortar using non-cement binder to solve indentation due to reduction of compressive strength on exiting Loess bicycle load.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.287-288
• /
• 2010

The purpose of this study aimed to evaluate properties of water resistance, disease of freezing and thawing and XRF of Loess mortar using non-cement binder to solve reduction of durability by freezing and thawing on exiting Loess bicycle load.

• Journal of Energy Engineering
• /
• v.12 no.4
• /
• pp.302-308
• /
• 2003

The peformence tests of zinc-based desulfurization sorbents using the yellow earth as support for the hot gas clean up were carried out. The zinc-based sorbent with 25 wt％ yellow earth was prepared, and their properties such as the reaction rate, the sulfur capacity and the attrition resistance, were investigated. The reactivity tests for hot gas desulfurization was performed at middle temperatures (sulfidation/regeneration：480$^{\circ}C$/580$^{\circ}C$). During multi-cyclic desulfurization, the deactivation of zinc-based sorbent was decreased by the addition of yellow earth, and their efficiency was enhanced. The ZnO/yellow earth sorbent had high reactivity, good regenerability, long-term durability (about 19 gS/100 g sorbent for 10-cycles) and high attrition resistance (AI=19.1％). It was concluded that the peroperties of zinc-based sorbent were improved by metal oxides (Fe$_2$O$_3$, Na$_2$O, MnO$_2$, etc) in the yellow earth. From these results, it was confirmed that the desulfurization properties of zinc-based sorbents at middle temperatures could be improved by the yellow earth using as support.

• Journal of the Korea Concrete Institute
• /
• v.20 no.5
• /
• pp.549-555
• /
• 2008

In this paper, the applicability of Hwangtoh, as an alternative of cement paste, is investigated for the solution of internal heat and shrinkage caused by the hydration of cement paste. Several small-sized specimens of Hwangtoh and ordinary portland concrete (OPC) were compared as to compressive strength, heat of hydration, and shrinkage strain. Moreover, the applicability to the construction structures was reviewed through the test of large-size specimens. The 28-day compressive strength of Hwangtoh concrete (HBC), ranged 18 to 33 MPa, can reach that of OPC. Not only the maximun internal temperature of HBC was read about 1/4 of OPC as it is cured, but also its shrinkage decreased more than the OPC did. Therefore, Hwangtoh binder is more favorable than cement binder in terms of its hydration heat and shrinkage under the construction of concrete.

• Journal of the Korea Institute of Building Construction
• /
• v.10 no.3
• /
• pp.49-56
• /
• 2010

The purpose of this study is to examine the effect of variations in the mix rate of PVA fiber and the replacement ratio of non-sintering Hwangtoh on non-sintering Hwangtoh mortar and concrete mixed with PVA fiber. For water to binder ratio, mortar and concrete were both 50%, and PVA fiber mix rate was 0% and 0.3%. The replacement ratio of non-sintering Hwangtoh was 0, 25, 50 and 75(%) for mortar, and 0, 15, 30 and 50(%) for concrete. The properties of the mortar and concrete were compared and analyzed in 4 different levels, and the results can be summarized as follows. The replacement ratio of 30% of the non-sintering Hwangtoh, and the PVA fiber mix rate of 0.3% is determined to result in concrete of high quality, including strength and fluidity, and crack control by plastic shrinkage.

• Journal of the Korea Institute of Building Construction
• /
• v.14 no.2
• /
• pp.170-176
• /
• 2014

This study examined the effect of chemical attack on the stress-strain relationship of alkali-activated Hwangtoh concrete. Water-to-binder ratio and air content were selected as mixture parameters. The stress-strain relationship of concrete was measured at chemical immersion times of 0, 7, 28, 56, and 91 days from an age of 28 days. Based on the test results, the reduction in compressive strength of alkali-activated hwangtoh concrete owing to chemical attack was formulated. In sddition the present study demonstrated that the stress-strain behavior of concrete under chemical attack is significantly dependent on the air content and chemical immersion time, indicating the rate of decrease of modulus of elasticity was greater than that of compressive strength at the same immersion time. As a result, the stress-strain behavior of concrete under chemical attack was significantly inconsistent with the conventional models specified in the CEB-FIP provision.