• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.610-616
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• 2011

A series of polyurethane acrylate/ZnO (PUA/ZnO) nanocomposite films with different ZnO contents were successfully prepared via a UV-curing system. The synthesis and physical properties including morphological structure, thermal properties, barrier properties and optical properties, and antimicrobial properties were investigated as a function of ZnO concentration. FTIR and SEM results showed that these PUA/ZnO nanocomposite films did not have a strong interaction between PUA and ZnO, which may lead to no increase in thermal stability. By incorporating ZnO nanoparticles, the UV blocking and antibacterial properties increased as the content of ZnO increased. Specially, the oxygen permeability in composite films changed from $2005cc/m^2/day$ to $150cc/m^2/day$ by adding the ZnO nanoparticle, which indicates that the PUA/ZnO nanocomposite films can be applied as good barrier packaging materials. Physical properties of the UV-cured PUA/ZnO nanocomposite film are strongly dependent upon the dispersion state of ZnO nanoparticles and their morphology in the films.

• Journal of Ginseng Research
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• v.45 no.2
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• pp.228-235
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• 2021

Backgroud: Ginsenoside compound K (GK) is a major metabolite of protopanaxadiol-type ginsenosides and has remarkable anticancer activities in vitro and in vivo. This work used an ionic cross-linking method to entrap GK within O-carboxymethyl chitosan (OCMC) nanoparticles (Nps) to form GK-loaded OCMC Nps (GK-OCMC Nps), which enhance the aqueous solubility and stability of GK. Methods: The GK-OCMC Nps were characterized using several physicochemical techniques, including x-ray diffraction, transmission electron microscopy, zeta potential analysis, and particle size analysis via dynamic light scattering. GK was released from GK-OCMC Nps and was conducted using the dialysis bag diffusion method. The effects of GK and GK-OCMC Nps on PC3 cell viability were measured by using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Fluorescent technology based on Cy5.5-labeled probes was used to explore the cellular uptake of GK-OCMC Nps. Results: The GK-OCMC NPs had a suitable particle size and zeta potential; they were spherical with good dispersion. In vitro drug release from GK-OCMC NPs was pH dependent. Moreover, the in vitro cytotoxicity study and cellular uptake assays indicated that the GK-OCMC Nps significantly enhanced the cytotoxicity and cellular uptake of GK toward the PC3 cells. GK-OCMC Nps also significantly promoted the activities of both caspase-3 and caspase-9. Conclusion: GK-OCMC Nps are potential nanocarriers for delivering hydrophobic drugs, thereby enhancing water solubility and permeability and improving the antiproliferative effects of GK.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.456-462
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• 2023

An electrically conductive and transparent electrode was created by applying a dispersion of pristine single-walled carbon nanotubes (SWCNTs) and silver nanowires to a polyethylene terephthalate (PET) film using a bar coating method. The SWCNTs were added to increase the electrical conductivity and transmittance of the silver nanowires while also preventing the haze from increasing due to the stacking of multiple layers containing SWCNTs and silver nanowires on the PET substrate. The silver nanowires in the electrode were also found to be stable against oxidation. The transparent electrode displayed excellent electrical and optical properties, with a sheet resistance of 47 Ω/□, transmittance of 96.72%, and haze of 1.93%. Additionally, the sheet resistance of the electrode remained stable over time, with a change of only 6.4% after a constant temperature and humidity test, making it suitable for long-term use. A hybrid transparent electrode that is economically feasible and environmentally sustainable has been developed through the utilization of pristine SWCNT and silver nanowire.

• Atmosphere
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• v.34 no.2
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• pp.203-216
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• 2024

The National Institute of Meteorological Sciences in Korea has developed the Weather Modification Hybrid Rocket (WMHR), an advanced system that offers enhanced stability and cost-effectiveness over conventional solid-fuel rockets. Designed for precise operation, the WMHR enables accurate control over the ejection altitude of pyrotechnics by modulating the quantity of oxidizer, facilitating specific cloud seeding at various atmospheric layers. Furthermore, the rate of descent for pyrotechnic devices can be adjusted by modifying parachute sizes, allowing for controlled dispersion time and concentration of seeding agents. The rocket's configuration also supports adjustments in the pyrotechnic device's capacity, permitting tailored seeding agent deployment. This innovation reflects significant technical progression and collaborations with local manufacturers, in addition to efforts to secure testing sites and address hybrid rocket production challenges. Notable outcomes of this project include the creation of a national framework for weather modification technology utilizing hybrid rockets, enhanced cloud seeding methods, and the potential for broader meteorological application of hybrid rockets beyond precipitation augmentation. An illustrative case study confirmed the WMHR's operational effectiveness, although the impact on cloud seeding was limited by unfavorable weather conditions. This experience has provided valuable insights and affirmed the system's potential for varied uses, such as weather modification and deploying high-altitude meteorological sensors. Nevertheless, the expansion of civilian weather rocket experiments in Korea faces challenges due to inadequate infrastructure and regulatory limitations, underscoring the urgent need for advancements in these areas.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.353-360
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• 1984

As an effort to expand the utilization of mackerel which has been thought disadvantageous to processors due to the defects in bloody dark color of meat, high content of lipid, and low stability of protein, and to develope a new type of product, so called, preservative fish meat paste, the processing method was studied in which dielectric heating was applied by means of cooking, pasteurization, dehydration, and control of water activity. The principle of this method is based on that dielectric heating can initiate a rapid dispersion or displacement of moisture in the meat tissue so that the level of water acivity can be controlled by dehydration with hot air meanwhile the product is cooked, pasteurized, and texturized. And the product is finally heated with electric heaters and vacuum sealed to stabilize water activity and storage stability. In present paper, a formula for preparing the fish meat-stach paste, the conditions of dielectric heating and dehydration, shape and size of the product, and other parameters were tested to optimize the process operation. A formula of the fish meat-starch paste to provide proper textural properties and water activity was $10\%$ starch, $1.5\%$ salt, $3\%$ soybean, $0.6\%$ MSG, $2\%$ sucrose, and $3\%$ sorbitol against the weight of fish meat. A proper shape and size of the product to avoid foaming and case hardening during heating was sliced disc of 8 cm $diameter{\times}0.8$ cm thickness or $10{\times}10$ cm square plate with 1.0 cm thickness. The disc shape was recommended because it resulted more uniform heating, minimum foaming and case hardening. And it was also advantageous that disc was simply provided when the fish meat disc was stuffed in the same, solidified in boiling water for 2 to 3 minutes, and sliced. Condition of dielectric heating was critical to decide the levels of sterility, water activity, and textural property of the product. The temperature at the center of the meat disc slices was raised up to $95^{\circ}C$ in 1.5 minutes so that continuous exposure to microwave caused expanded tissue and hardening ending up with a higher water content. Heating for 5 to 6 minutes was adequate to yield the final water activity of 0.86 to 0.83(35 to $40\%$ moisture). It is important, however, that heating had to be done periodically, for instance, in the manner of 2.0, 1.5, 1.5, and 1.0 minute to give enough time to displace or evaporate moisture from the meat tissue. The product was dehydrated for 2 to 3 minutes by hot air of $60^{\circ}C$, 3 to 5m/sec and finally exposed to electric heaters for 5 to 6 minutes until the surface was roasted deep brown. These conditions of heating and dehydration resulted in a complete reduction of total plate count from an initial count of $5.3{\times}10^6/g$ to less than $3{\times}10^2/g$. General composition of the product was $40.1\%$ moisture, $20.8\%$ protein, $17.4\%$ lipid, $16.2\%$ carbohydrate, and $5.5\%$ ash. Textural properties revealed folding test AA, hardness 42, cohesiveness 0.53, toughness 4.6, and elasticity 0.8.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.304-314
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• 2004

The objective of this study was to investigate the effect of organic materials (compost, straw, green manure, pig manure, seed production oil cake, and industrial by products including municipal sewage sludge, industrial sewage sludge, leather processing sludge, and alcohol fermentation processing sludge) on physical properties of soils in seven paddy and four upland fields with differential soil textures, sandy loam, loam, or clay loam, etc. The investigated physical parameters were bulk density (BD), air permeability (AP), macroporosity, hardness, shear resistance, frictional resistance, water stability aggregate (WSA), and Middleton's dispersion ratio. Except for coarse sandy loam field with weak structure, a decrease in BD and shear resistance, and an increase in macroporosity and AP in plots with applying organic materials compared to plots without applying organic materials appeared. In upland fields, the positive effect of organic materials on WSA, BD, and air permeability was higher than in paddy fields. The combined plot of NPK and compost had lower BD, hardness, and shear resistance, and higher macroporosity and WSA than plot with compost. Green manure had higher positive effect on physical properties of soils compared to other organic materials and the extent of positive effect had no significant correlation with soil organic matter content. Of industrial byproducts applied in coarse sandy loam soil under upland condition, municipal sewage sludge and pig manure compost had higher effect on increase of WSA than leather processing sludge and alcohol fermentation processing sludge. Unlike WSA, there were no significant differences between industrial byproduct types in other physical properties. in silty clay loam soil under the upland condition, straw had more positive effect on soil physical parameters than hairy vetch and pig manure. Therefore, different organic materials had differently active effect on physical parameters depending on types of soil and land use. Especially, it could be thought that well-decomposed organic materials have the advantage of an increase in organic matter content, while coarse organic materials of an increase in WSA.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.215-223
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• 1978

In Korea, the annual production of watermelon and cantaloupe melon is around 110,000 to 170,000 Metric Tons, and as the fruit does not keep well, studies were conducted to determine the feasibility of preservation in the form of natural juice or lactic fermented juice. The results obtained in these studies are summarized as follows: (1) The average yield of juice obtained from watermelon was 56.2%, and from cantaloupe melon 65.8%, of the fresh weight. (2) The colloidal components of watermelon juice separated from the juice by sedimentation within 24 hours. Cantaloupe melon juice gave a stable colloidal dispersion. (3) No change in the colour of the juices was detected by sensory evaluation or instrumental methods after they were treated at $100^{\circ}C$ for 5 minutes. (4) The addition of canesugar to give a total solids content of 11/13 Brix gave juices which were preferred by most tasters. (5) Lactic fermentation of natural juices pasteurised at $90^{\circ}C$ for 5 minutes, and inoculated with a pure culture of lactic acid bacteria proceeded without interference from competing microorganisms. (6) Sensory evaluation of lactic fermented juices indicated that 60% of tasters found the juices as acceptable or better than commercial fruit nectars at present on the market. (7) Taste panels showed a preference for natural melon juices over the lactic fermented juices. (8) The peroxidase activity of cantaloupe melon juice was higher than that of watermelon juice, with juice extracted from the core of the fruit showing a higher activity than that from other portions of the tissue. (9) Two types of peroxidase, of differing heat stability were detected in both juices. The more heat stable peroxidase had a decimal reduction time of 40 minutes at $80^{\circ}C$ and a z value of $11^{\circ}C$.

• Korean Security Journal
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• no.14
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• pp.413-429
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• 2007

The Guard over the royal household in the "Goryeo" era was the same as if was over the President or Ruler of a nation today. In those days, a king represented a nation and any threat to the safety of a king could bring the destruction of a nation and the dispersion of the people. by reviewing the change of the 2-Gun 6-Wi system of the era, it can be, summed up as follow, Ther will be suggestions. The Guard might focus on a king's personal safety in the wake of the system of the Silla and Taebong dynasties until the establishment of the Goryeo Dynasty's unique political system. "Goryeo" rebuilt the royal palace in Gyeonyeong-gun to take the shape of unified country after its accomplishment of unification of the late three countries, Then it was afraid of the rebellion and uprising of local powerful clans, The country put them under control and organized the local army with them in the era of Kings, Seongjong, through the kings, Seongjong and Gwangjong. The army system of "Goryeo" consisted of 2-Gun and 6-Wi, and 2-Gun placed above the 6-Wi played the role of the Royal guards, and among the organizations a certain army under the specific name of "Gyeonyong-gun" guarded the kings in the nearest position. An aristocratic culture enjoyed its golden age in the period of stability of the aristocracy of "Goryeo", but afterward in the confusion of the aristocratic disruption and incompatible confrontation the country lost its control, and faced military rebellions by treating civil officials well and ill-treating military officials The safety of kings become unstable with the grasping political power by the military officials, and "Dobang" was established in the era of Choi's family to grasp political power. In the era of Choi Woo, he gathered his men and organized his familys army with them and managed the personnel administration with the civil officials of "Jeongbang and Seobang under his command. Such a fact shows the similarity to today's task of guarding. Considering the facts that "Sambyeolcho, the military ground of the military-men-rule, was at the center of the struggling against Mongolia and that even after the fall of the military regime, they rebelled and fought against Mongolia to the end, we came to know that the nationalism in the era of the military era was great. In the transition of external situations from "Myeong" to "Won"(Chinese dynasties), the conflict between the old "Won"-friendly power and the new "Myeong"-friendly power caused the weakness of the power to guard the royal household, and "Goryeo" at last gave way to the newly rising "Joseon" led by Lee, Seong Gye who won the people's confidence.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.212-228
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• 2013

Stone cultural heritages are repaired by the use of metal stiffeners. The problem is that this type of repair has been based on the experience of workers without specific guidelines and has caused various problems. This is to suggest the structural reinforcement and behavioral characteristics of metal rods to minimize the secondary damage of materials and have the specimens tested and verified to establish the guidelines on how to insert metal stiffeners. When only epoxy resin is applied to the cut surface, only 70% of the properties of the parent material are regenerated and it is required to structurally reinforce the metal stiffener for the remaining 30%. The metal rod is under the structural behavior after the brittle failure of stone material and the structural behavior does not occur when the metal stiffener is below 0.251%. When it accounts for over 0.5%, it achieves structural reinforcement, but causes secondary damage of parent materials. The appropriate ratio of metal stiffener for the stone material with the strength of $1,500kgf/cm^2$, therefore, should be between 0.283% and 0.377% of the cross section of attached surface to achieve reversible fracture and ductility behavior. In addition, it is more effective to position the stiffeners at close intervals to achieve the peak stress of metal rod against bending load and inserting the stiffener into the upper secions is not structurally supportive, but would rather cause damage of the parent material. Thus, most stiffeners should be inserted into the lower part and some into the central part to work as a stable tensile material under the load stress. The dispersion effect of metal rods was influenced by the area of reinforcing rods and unrelated to their diameter. However, it ensures stability under the load stress to increase the number of stiffeners considering the cross section adhered when working on large-scale structures. The development length is engineered based upon the diameter of stiffener using the following formula: $l_d=\frac{a_tf_y}{u{\Sigma}_0}$. Also, helically-threaded reinforcing rods should be used to perform the behaviors as a structural material.

• Korean Journal of Heritage: History & Science
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• v.44 no.1
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• pp.72-105
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• 2011

This study explores the value of the Dicentra spectabilis community as a nature reserve in provincial forests at San 1-2, Daea-ri, Dongsang-myeon, Wanju-gun, Jellabuk-do, also known as Gamakgol, while defining the appropriateness of its living environment and eventually providing basic information to protect this area. For these reasons, we investigated 'morphological and biological features of Dicentra spectabilis' and the 'present situation and problems of designing a herbaceous nature reserve in Korea.' Furthermore, we researched and analyzed the solar, soil and vegetation condition here through a field study in order to comprehend its nature reserve value. The result is as follows. According to the analytic result for information on the domestic wild Dicentra spectabilis community, it is evenly spread throughout mountainous areas, and there is one particularly outstanding in size in Wanju Gamakgol. Upon the findings from literature and the field study about its dispersion, Gamakgol has been discovered as an ideal district for Dicentra spectabilis since it meets all the conditions this plant requires to grow vigorously, such as a quasi-high altitude and rich precipitation during its period of active growth duration in May. Dicentra spectabilis grows in rocky soil ranging from 300~375m above sea level, 344.5m on average, towards the north, northwest and dominantly in the northeast. The mean inclination degree is $19.5^{\circ}$. Also, upon findings from analyzing solar conditions, the average light intensity during its growth duration, from Apr. to Aug., is 30,810lux on average and it tends to increase, as it gets closer to the end. This plant requires around 14,000~18,000lux while growing, but once bloomed, fruits develop regardless of the degree of brightness. The soil pH has shown a slight difference between the topsoil, at 5.2~6.1, and subsoil, at 5.2~6.2. Its mean pH is 5.54 for topsoil and 5.58 for subsoil. These results are very typical for Dicentra spectabilis to grow in, and other comparative areas also present similar conditions. Given the facts, the character of the soil in Gamakgol has been evaluated to have high stability. Analysis of its vegetation environment shows a wide variation of taxa numbering from 13 to 52 depending on area. The total number of taxa is 126 and they are a homogenous group while showing a variety of species as well. The Dicentra spectabilis community in the Daea-ri Arboretum is an herbaceous community consisting of dominantly Dicentra spectabilis, Cardamine leucantha, Boehmeria tricuspi and Impatiens textori while having many differential species such as Impatiens textori, Pueraria thunbergiana, Rubus crataegifolius vs Staphylea bumalda, Securinega suffruticosa, and Actinidia polygama. It suggests that it is a typical subcolony divided by topographic features and soil humidity. Considering the above results on a comprehensive level, this area is an excellent habitat for wild Dicentra spectabilis providing beautiful viewing enjoyment. Additionally, it is the largest wild colony of Dicentra spectabilis in Korea whose climate, topography, soil conditions and vegetation environment can secure sustainability as a wild habitat of Dicentra spectabilis. Therefore, We have determined that the Gamakgol community should be re-examined as natural asset owing to its established habitat conditions and sustainability.