• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.1
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• pp.36-43
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• 2006

The principal aim of this field study was to determine the concentrations and emissions of gaseous contaminants such as ammonia and hydrogen sulfide in the different types of pig buildings in Korea and allow objective comparison between Korea and the other countries in terms of pig housing types. This field study was performed from May to June and from September to October in 2002. Pig buildings investigated in this research were selected in terms of three criteria; manure removal system, ventilation mode and growth stage of pig. Measurements of concentration and emission of ammonia and hydrogen sulfide in the pig buildings were done in 5 housing types and the visited farms were 15 sites per each housing type. Concentrations of ammonia and hydrogen sulfide were measured at three locations of the central alley in the pig building and emission rates of them were estimated by multiplying the average concentration($mg/m^3$) measured near the air outlet by the mean ventilation rate($m^3/h$) and expressed either per pig of liveweight 75kg(mg/h/pig) or per area($mg/h/m^2$). Concentrations of ammonia and hydrogen sulfide in the pig buildings were averaged to 7.5 ppm and 286.5 ppb and ranged from 0.8 to 21.4 ppm and from 45.8 to 1,235 ppb, respectively. The highest concentrations of ammonia and hydrogen sulfide were found in the mechanically ventilated buildings with slats; 12.1 ppm and 612.8 ppb, while the lowest concentrations of ammonia and hydrogen sulfide were found in the pig buildings with deep-litter bed system(2.2 ppm) and the naturally ventilated pig buildings with manure removal system by scraper(115.2 ppb), respectively(p<0.05). All the pig buildings were investigated not to exceed the threshold limit values(TLVs) of ammonia(25 ppm) and hydrogen sulfide(10 ppm). The mean emissions of ammonia and hydrogen sulfide per pig(75kg in terms of liveweight) and area($m^2$) from pig buildings were 250.2 mg/h/pig and 37.8 mg/h/pig and $336.3mg/h/m^2$ and $50.9mg/h/m^2$, respectively. The pig buildings with deep-litter bed system showed the lowest emissions of ammonia and hydrogen sulfide(p<0.05). However, the emissions of ammonia and hydrogen sulfide from the other pig buildings were not significantly different(p>0.05). Concentrations and emissions of ammonia and hydrogen sulfide were relatively higher in the pig buildings managed with deep-pit manure system with slats and mechanical ventilation mode than the different pig housing types. In order to prevent pig farm workers from adverse health effect caused by exposure to ammonia and hydrogen sulfide in pig buildings, they should wear the respirators during shift and be educated sustainably for the guideline related to occupational safety.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.62-62
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• 1999

Carbon based materials have many attractive properties such as a wide band gap, a low electron affinity, and a high chemical and mechanical stability. Therefore, researches on the carbon-based materials as field emitters have been drawn extensively to enhance the field emission properties. Especially, diamond gives high current density, high current stability high thermal conductivity durable for high temperature operation, and low field emission behaviors, Among these properties understanding the origin of low field emission is a key factor for the application of diamond to a filed emitter and the verification of the emission site and its distribution of diamond is helpful to clarify the origin of low field emission from diamond There have been many investigations on the origin of low field emission behavior of diamond crystal or chemical vapor deposition (CVD) diamond films that is intentionally doped or not. However, the origin of the low field emission behavior and the consequent field emission mechanism is still not converged and those may be different between diamond crystal and CVD diamond films as well as the diamond that is doped or not. In addition, there have been no systematic studies on the dependence of nondiamond carbon on the spatial distribution of emission sites and its uniformity. Thus, clarifying a possible mechanism for the low field emission covering the diamond with various properties might be indeed a difficult work. On the other hand, it is believed that electron emission mechanisms of diamond are closely related to the emission sites and its distributions. In this context, it will be helpful to compare the spatial distribution of emission sites and field emission properties of the diamond films prepared by systematic variations of structural property. In this study, we have focused on an understanding of the field emission variations of structural property. In this study, we have focused on an understanding of the field emission mechanism for the CVD grown undoped polycrystalline diamond films with significantly different structural properties. The structural properties of the films were systematically modified by varying the CH4/H2 ratio and/or applying positive substrate bias examined. It was confirmed from the present study that the field emission characteristics are strongly dependent on the nondiamond carbon contents of the undoped polycrystalline diamond films, and a possible field emission mechanism for the undoped polycrystalline diamond films is suggested.

• The Korean Journal of Food And Nutrition
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• v.16 no.2
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• pp.158-164
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• 2003

This study was conducted to investigate the properties of noodle which was made of composite flour blended with the powder of synnemata of Beauveria bassiana. The characteristics of cooked-noodle including color, cooking properties, mechanical texture properties were measured, and sensory evaluation was performed. The L-value of dry and wet-noodle which made of composite flour was similar to that of 100% wheat flour, but a and b-value were higher than those of 100% wheat flour. There were no differences in the weight, volume and water absorption of the cooked-noodle made of composite flour and that of 100% wheat flour, but the turbidity of the cooked-noodle made of composite flour was higher than that of 100% wheat flour. The breaking force of dry-noodle which was made of composite flour was same as that of 100% wheat flour. Hardness and Gumminess of the cooked-noodle which was made of composite flour blended with synnemata powder at level of 1∼5% were same as those of 100% wheat flour. Springiness, chewiness, cohesiveness and adhesiveness of the cooked-noodle which was made of composite flour blended with synnemata powder at level of 1% were similar to those 100% wheat flour. The results of sensory evaluation showed that the cooked-noodles containing 1% and 3% synnemata powder were acceptable as much as those of 100% wheat flour in terms of color, taste, flavor, texture and overall acceptance.

• Korean journal of food and cookery science
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• v.17 no.3
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• pp.204-210
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• 2001

Rice cakes were prepared by the addition of yellow soybean flour or peanut flour and packaged with $CO_2$-modified packaging(CMP) or vacuum packaging(VP), and their physical characteristics were monitored by sensory evaluation and mechanical measurement while storing for 6 days. For VP samples, yellow soybean rice cake showed little changes in cohesiveness, moistness and chewiness for 6 days of storage, while pure rice cake and peanut rice cake showed an increase in strength and hardness from the 4th day of storage. In case of CMP, yellow soybean rice cake hardly showed a difference in cohesiveness, moistness and chewiness for 6 days, while pure rice cake and peanut rice cake showed a significant difference from the 4th day in sensory evaluation. For rheometer measurement, yellow soybean rice cake with CMP or VP showed little changes in strength or hardness for 6 days, while peanut rice cake and pure rice cake showed a drastic decrease in cohesiveness from the 2nd day and adhesiveness from the 4th day of storage. As there was no remarkable difference or deterioration for 6 days of storage in yellow soybean rice cake between CMP and VP, the ingredients of rice cake appeared to be more important than the type of packaging in terms of the quality deterioration of rice cake.

• Korean journal of food and cookery science
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• v.31 no.2
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• pp.175-184
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• 2015

The purpose of this study was to determine the optimal mixing ratio of Agaricus blazei Murill powder and butter in the preparation of cookies. The experimental design utilized herein was based on central composite design for response surface methodology, which included 10 experimental points, including 2 replicates for Agaricus blazei Murill and butter. The physical, mechanical, and sensory properties of the test were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the final mixed product. The spread ratio increased significantly with an increase in Agaricus blazei Murill powder and butter (p<0.05). The response surface methodology was applied to evaluate the effect of Agaricus blazei Murill powder and butter on cookie moisture and color (L, a) (p<0.001). Sensory evaluation showed significant values for color (p<0.05), flavor (p<0.05), texture (p<0.05) and overall quality (p<0.01) in the predicted model. The optimum formulation by numerical and graphical methods was calculated as follows: Agaricus blazei Murill powder 3.63 g, butter 55.37 g.

• Food Science of Animal Resources
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• v.33 no.6
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• pp.757-762
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• 2013

This study was conducted to develop a processing method for dry-curing beef ham with Korean traditional sauces and to investigate the quality properties of the dry-cured beef hams. Semitendinosus muscle from Hanwoo was spread with sundried salt (C), sun-dried salt mixed with red pepper paste (T1), and sun-dried salt mixed with soybean paste (T2), and inserted into washed Hanwoo large intestine. It was then dried and fermented for 75 d. Moisture contents of the hams were 46-48%, without any significant differences. T1 showed the lowest pH among the three dry-cured hams, while water holding capacity (WHC) of T2 was found the lowest (p<0.05). In mechanical color determination, C showed higher CIE $a^*$ and CIE $b^*$ than T1 and T2 (p<0.05), however CIE $L^*$ did not show any significant difference. In texture, T1 demonstrated significantly lower springiness than C (p<0.05). The sensory properties of all dry-cured hams did not show any significant difference, but T1 indicated a higher taste, saltiness and overall acceptability than others, whereas C gathered the highest score in color and flavor. In conclusion, the dry-curing by combination of sun-dried salt mixed with red pepper sauce (T1) showed higher quality properties of the Hanwoo dry-cured ham.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.102-108
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• 1997

ZrO2 powders stabilized with Y2O3 and CeO2 of various compositions were prepared by the coprecipitation of water-soluble ZrOCl2.8H2O, YCl3.6H2O and Ce(NO3)3.6H2O, and their compacts were pressurelessly sintered at 1400 and 150$0^{\circ}C$ for 2hrs in air. 2mol% Y2O3-ZrO3 showed the most superior strength (1003MPa) and microhardness (12.6GPa), while 10 mol%CeO2-ZrO2 had the hightest toughness (13.3 MPa.m1/2) after sintering at 140$0^{\circ}C$. The addition of Y2O3 into Y2O3-ZrO3 decreased mean grain size and increased strength and hardness but decrease toughness. On the other hand, the addition of CeO2 into Y2O3-ZrO2 enhanced the stability of tetragonal phase during low-temperature aging for a long time under hydrothermal atmosphere.

• Journal of Periodontal and Implant Science
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• v.46 no.6
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• pp.362-371
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• 2016

Purpose: The increasing demand for esthetically pleasing results has contributed to the use of ceramics for dental implant abutments. The aim of this study was to compare the biological response of epithelial tissue cultivated on lithium disilicate ($LS_2$) and zirconium oxide ($ZrO_2$) ceramics. Understanding the relevant physicochemical and mechanical properties of these ceramics will help identify the optimal material for facilitating gingival wound closure. Methods: Both biomaterials were prepared with 2 different surface treatments: raw and polished. Their physicochemical characteristics were analyzed by contact angle measurements, scanning white-light interferometry, and scanning electron microscopy. An organotypic culture was then performed using a chicken epithelium model to simulate peri-implant soft tissue. We measured the contact angle, hydrophobicity, and roughness of the materials as well as the tissue behavior at their surfaces (cell migration and cell adhesion). Results: The best cell migration was observed on $ZrO_2$ ceramic. Cell adhesion was also drastically lower on the polished $ZrO_2$ ceramic than on both the raw and polished $LS_2$. Evaluating various surface topographies of $LS_2$ showed that increasing surface roughness improved cell adhesion, leading to an increase of up to 13%. Conclusions: Our results demonstrate that a biomaterial, here $LS_2$, can be modified using simple surface changes in order to finely modulate soft tissue adhesion. Strong adhesion at the abutment associated with weak migration assists in gingival wound healing. On the same material, polishing can reduce cell adhesion without drastically modifying cell migration. A comparison of $LS_2$ and $ZrO_2$ ceramic showed that $LS_2$ was more conducive to creating varying tissue reactions. Our results can help dental surgeons to choose, especially for esthetic implant abutments, the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.1
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• pp.90-98
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• 2008

Nanotechnology(NT) refers to a field of advanced micro-technology covering the creation and manufacturing of materials on the atomic and molecular scale and requires interdisciplinary study with various fields including materials science, physics, chemistry, electronics and others. Whileas nanotechnology is a kind of micro and small scaled science, space technology(ST) is one of the larger and system technologies utilizing broad fields of mechanical, materials, electronics and communication technologies. It is necessary to select and concentrate the functional items of nanotechnology for efficient application to be utilized in space technology, due to the cross-sectional characteristics of nanotechnology within nanomaterials, nanoelectronics, and nanomanufacturing. This paper provides the current state of art of nanotechnology in space technology by evaluating NASA's activities and the 9th frame of the project ANTARES(Analysis of Nanotechnology Applications in Space Developments and Systems) with the support of the German Aerospace Center (DLR), Space Flight Management, Division Technology for Space Systems and Robotics. It has shown that it is necessary to apply nanotechnology to space technology in order to achieve international competitiveness, for the nanotechnology can bring the previously impossible things to reality. Since KARI plans to send an unmanned probe to the moon's orbit and land a probe on the moon's surface in 2025, it is urgently needed to incorporate nanotechnology to national space development plan.

• Composites Research
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• v.13 no.6
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• pp.1-8
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• 2000

The fabrication Process of $Al_2O_{3p}$/AC8A composites by pressureless infiltration technique and the effects of additive Mg content and volume fraction of particulate reinforcement on mechanical and wear properties were investigated. It was found that the bending strength decreased with increasing volume fraction of $Al_2O_{3p}$ particles. Whereas hardness increased with volume fraction of $Al_2O_{3p}$ particles. The decrement of strength in case of high volume fraction of $Al_2O_{3p}$ particles was attributed to high porosity level. In terms of additive Mg content, $Al_2O_{3p}$/AC8A composites containing around 5~7wt% of additive Mg indicated the highest strength, and hardness values increased with additive Mg contents. Wear resistance of AC8A alloy were improved by reinforcement of $Al_2O_{3p}$ particles especially at high sliding velocity. Wear property of $Al_2O_{3p}$/AC8A composites and AC8A alloy exhibited different aspects. $Al_2O_{3p}$/AC8A composites indicated more wear loss than AC8A alloy at slow velocity region. However a transition point of wear loss was found at middle velocity region which shows the minimum wear loss and wear loss at high velocity region exhibited almost same value as at slow velocity region, whereas wear loss of AC8A alloy almost linearly increased with sliding velocity. It was found that $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 20% exhibited abrasive wear surface regardless of sliding velocity and $Al_2O_{3p}$/AC8A composites containing $Al_2O_{3p}$ volume fraction of 40% showed slightly adhesive wear surface at low sliding velocity, and it progressed to severe wear as increasing the sliding velocity.