• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1154-1161
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• 2006

Air drying equipment was built as a device for reduction of dewatered cake from wastewater and waterworks sludge and to reproduce it by reusable matter. Dewatered cake was supplied into the air drying equipment which operated by air velocity of 80 m/sec, air rate 30 $m^3/min$ and air temperature of $40^{\circ}C$, and dried to produce the dried powder. The air drying equipment was composed of the air ejector which made high-speed fluid field, and cyclone which made circling fluid field. Dewatered cake was crushed at the high-speed zone as first step, and formed into dried powder of sphere shape by the collision between particles at the circling fluid zone.. Wastewater sludge with water content of 82.5 wt% was supplied 1.0 kg/min into air drying equipment and produced the dried powder which had the water content of 62.3 wt% and mass median diameter of 2.4 mm after process. At that time, it was analyzed that water removal rate was 0.1 $H_2O{\Delta}kg/min{\cdot}DS$ kg and air consumption was 170 $m^3/DS$ kg. Under same experimental conditions, when waterworks sludge was dried, water content of dried powder decrease to 47.5 wt% and mass median diameter decrease 2.1 mm and water removal rate increase 0.13 $H_2O{\Delta}kg/min{\cdot}DS$ kg. Air consumption increase 180 $m^3/DS$ kg with comparison to the results of wastewater sludge. Therefore, this technology was evaluated that drying the dewatered cake of waterworks sludge was more efficient than wastewater sludge, and also economical sludge handling technology due to drying the cake by only air.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.452-455
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• 2009

The Nakdong Delta can be identified by two different geomorphic units. The first one is the upper delta. This is mostly composed of inter-distributary islands that are largely influenced by fluvial processes and attributed to the development of these islands along the river. The other one is the lower delta which is mostly composed of beach ridges. Barrier islands are largely effected by wave processes promoted by the development almost at a right angle to the river. Influenced by the longshore current which flows to the same direction, barrier islands located in the Nakdong river estuary are developing from east to west direction. As a result, the eastern end of the barrier islands are growing toward the north-west direction effected by tidal current which moves toward the same direction. Barrier islands include the Sinho Island, the Jinwoo Island, the Daema deung, the Janga Island, the Baghap deung, the Sae deung, and the Chulsae deung(Doyeo deung). They have orderly emerged from the sea since 1861. Since 2008, a new Deung, a sand dune growing under sea, has been developing rapidly from Chulsae deung to the Dadaepo beach. It made the sailing of small fisher boats impossible. Tidal currents transported a lot of sand and silt around the barrier islands. The landscape of Nakdong river estuary where many barrier islands are distributed will change rapidly affecting land environment.

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.507-514
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• 2010

Peanut(Arachis hypogaea L.) is one of the major oilseed crops. The peanut oil consists of palmitic, oleic and linoleic acids, which are present at levels of 10%, 36-67% and 15-43%, respectively. High oleate mutant of peanut F435 contains 80% oleate and as little as 2% linoleate in seed oil. Previous study indicated that delta 12 fatty acid desaturase is a major enzyme controlling the oleate content in seeds of oilseed crops. F435 sequence alignment of their coding regions disclosed that an extra A(adenine) was inserted at the position +2,823 bp of delta 12 fatty acid desaturase gene. This study was to develop molecular marker (SNP marker) co-segregating with the high oleate trait. Chopyeong ${\times}$ F435 $F_2$ 41 population were investigated using molecular marker and fatty acid assay (NIR and gas chromatography). Finally, this marker segregates Chopyeong type 26 lines, heterotype 9 lines and F435 type 6 lines. These results in our study suggested that SNP marker conform fatty acid assay.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.203-209
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• 1999

LaAlO3d single phase used as the butter layer on Si wafer for YBa2Cu3O7-$\delta$ superconductor application were prepared by solid state reaction method and by self-sustaining combustion process. The microstructure and crystallity of synthesiszed LaAlO3 powder studied using scanning electron microscope (SEM) and X-ray diffractometer(XRD), specific surface area and sintering characteristics fo powder were investigated by Brunauer-Emmett-Teller (BET) method and dilatometer respectively. In solid state reaction method, it is difficult to obtain LaAlO3 single phase up to 150$0^{\circ}C$ period. However, in self-sustaining combustion process, it is to easy to do it only $650^{\circ}C$. Based on the results of analysis of dilatometer it is easier to obtain high sintering density (98.87%) in self-sustaining combustion process than in the solid state reaction method. This reason is that the average particle size prepared by self-sustaining combustion process is nano crystal size and has high specific surface are value(56.54 $m^2$/g) compared with that by solid state reaction method. Also, LaAlO3 layer on the Si wafer has been achieved by screen printing and sintering method. Even though the sintering temperature is 130$0^{\circ}C$, the phenomena of silicon out diffusion in LaAlO3/Si interphase are not observed.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.302-308
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• 2005

This study was performed to examine the absolute skin temperature and temperature difference $({\Delta}T)$ between the left and the right, the upper and the lower parts on the back of dog and to investigate the clinical usefulness of infrared thermography as diagnostic or prognostic aid on experimental spinal cord compression by using Digital Infrared Imaging System. In normal dogs, symmetrical and contouring patterns were observed in thermogram. The skin temperature difference was not significant between the left and the right, the upper and the lower parts on the back. In spinal cord compressed dog, there was symmetrical temperature reduction pattern around lesion. Patterns of ${\Delta}T$ between thoracic and lumbar portions were remarkable and showed the tendency to return to normal after 4 weeks of operation. It is considered that infrared thermography is a useful diagnostic and prognostic aid for spinal cord injury in dogs.

• Journal of the Economic Geographical Society of Korea
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• v.16 no.3
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• pp.423-444
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• 2013

Tourism in Thoi Son Islet has been the advanced model for rural tourism in the Mekong Delta region since the 1990s. The continuously rising number of tourists, however, has also created problems that affect sustainable rural development. To understand these problems, this research analyzed how rural tourism has been operated through the methodology of a stakeholder network. After investigating the network among key stakeholders (Ho Chi Minh travel agencies (HCMTAs), local travel agencies (LTAs), and local residents, the result showed that in the current model, HCMTAs and LTAs have played the role of connectors, working as hubs to shift tourists (demand) to match local residents (supply), with the networking being dominated by signed contracts (formal networks). The networks between LTAs and local residents are both formal and informal. Inter- and intra-networks among local residents are dominated by informal networks of established working relationships based on networks of family, friends, and neighbors. Moreover, this research has found that there is no cooperating network among LTAs. Among owners of tourist sites was not also found cooperating network. The primary motivating factor for these stakeholders is price competition; this has led to a disproportionately small share of revenue for local stakeholders, with most tourism revenue going to HCMTAs. Additionally, because of the high competition among local stakeholders, this results in local stakeholders having little or no negotiating power when conducting business with HCMTAs. Meanwhile the Tien Giang Tourism Association is inefficient in fostering cooperation among local stakeholders to increase their negotiating power.

• Restorative Dentistry and Endodontics
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• v.36 no.5
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• pp.377-384
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• 2011

Objectives: The purpose of this study was to observe the change in the viscoelastic properties of thermoplasticized injectable root canal filling materials as a function of temperature and to compare the handling characteristics of these materials. Materials and Methods: Three commercial gutta perchas and Resilon (Pentron Clinical Technologies) in a pellet form were heated in the Obtura-II system (Obtura Spartan) at $140^{\circ}C$ and $200^{\circ}C$, and the extrusion temperature of the thermoplasticized materials was measured. The viscoelastic properties of the materials as a function of temperature were evaluated using a rheometer. The elastic modulus G', viscous modulus G", loss tangent tan${\delta}$, and complex viscosity ${\eta}^*$ were determined. The phase transition temperature was determined by both the rheometer and a differential scanning calorimeter (DSC). The consistency of the materials was compared under compacting pressure at $60^{\circ}C$ and $40^{\circ}C$ by a squeeze test. Results: The three gutta perchas had dissimilar profiles in viscoelastic properties with varying temperature. The phase transition of softened materials into solidification occurred at $40^{\circ}C$ to $50^{\circ}C$, and the onset temperatures obtained by a rheometer and a DSC were similar to each other. The onset temperature of phase transition and the consistency upon compaction pressure were different among the materials (p < 0.05). Resilon had a rheologically similar pattern to the gutta perchas, and was featured between high and low-flow gutta perchas. Conclusions: The rheological characteristics of the thermoplasticized root canal filling materials changed under a cooling process. The dissimilar viscoelastic properties among the materials require different handling characteristics during an injecting and compacting procedure.

• Journal of the Korean Chemical Society
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• v.31 no.1
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• pp.55-63
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• 1987

The systematic investigation of the retention behaviors of 18 monosubstituted benzenes in reversed-phase liquid chromatography(RPLC) was studied in order to predict the separation possibility of their mixtures and study the contribution of substituent group to the retentions of solutes. The columns and mobile phases employed in this study were $\mu$ -Bondapak $C_{18}$, $\mu$-Bondapak phenyl columns and methanol/water, acetonitrile/water, and THF/water, respectively. The polar substituents such as phenol, aniline, acetophenone and benzonitrile have smaller capacity factor(k') values than benzene, while nonpolar ones such as alkylbenzenes and halobenzenes show larger k' value. The capacity factors of all solutes increased on both C18 bonded and phenyl bonded phases as the organic solvent content of three organic solvent-water mixtures decreased. The absolute differences in capacity factor(${\Delta}k$') between substituent and benzene were graphically shown for the prediction of the separation of the mixture and interpretation of the elution behavior of substituent. In addition, the selectivity of solvent system for the separation of the mixture was investigated in both two columns and three mobile phases.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.213-222
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• 2019

Birnessite (birnessite, $7{\AA}$ manganate, ${\delta}-MnO_2$) is a major mineral comprising manganese nodule. Various synthetic methods have been studied and evaluated because it can be used as an ion exchange agent and a battery recharging material. However, it is difficult to obtain a single birnessite phase because it does not have a stoichiometric chemical composition. Feitknechtite (${\beta}-MnOOH$) is formed as an intermediate product during birnessite synthesis and in this study, the transition of this phase to birnessite was compared by using XRD and SEM. Two different methods, Feng et al. (2004) and Luo et al. (1998), based on redox reaction were used. It was possible to obtain the impurity-free birnessite for the sample aged 60 days at $27^{\circ}C$ by Feng et al. (2004) method and 3 days at $60^{\circ}C$ by Luo et al. (1998) method. The phase transition rate of the feitknechtite phase was slower in the case of $Mg^{2+}$ doped birnessite which was synthesized by Luo et al. (1998) method, and almost single phase almost single phase birnessite was identified at high temperature. Crystal surface and morphology also confirmed the difference between the samples synthesized by two methods.

• Elastomers and Composites
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• v.39 no.3
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• pp.217-227
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• 2004

A new thermotropic liquid crystalline polymer(TLCP) containing a triad aromatic ester type mesogenic unit and butylene terephthalate unit(BT) in the main chain was synthesized by polycondensation reaction. The TLCP synthesized showed nematic mesophasic behavior and its transition temperature from solid to mesophase was $260^{\circ}C$. The TLCP/PBT blends were prepared by in-situ polymerization in PBT solution and characterized by differential scanning calorimeter(DSC), thermogavimetric analyzer(TGA), scanning electron microscope(SEM), x-ray diffractometer(XRD), and dynamic mechanical thermal analyze, (DMTA). The blends showed well dispersed TLCP phases with domain sizes $0.05{\sim}0.2{\mu}m$ in the PBT matrix. As the increasing TLCP content from 5 to 20 wt%, ${\Delta}Hm$ values of pure PBT in the blend were increased because TLCP acts as a nucleating agent in the PBT matrix. The mechanical properties of the blends depended on the TLCP contents because the TLCP acted effectively as a reinforcing material in the PBT matrix. The blends showed good interfacial adhesion between the TLCP phase and PBT matrix.The blends prepared by in-situ polymerization showed higher mechanical properties and well dispersed TLCP domains than those of the blends prepared by melt blending.