• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.29 no.1
• /
• pp.1-7
• /
• 2023

Chlorine dioxide (ClO₂) is widely used for post-harvest sterilization treatment. However, there are limitations in the retail application of ClO₂ due to difficulties in handling, expensive facilities, and safety concerns. Therefore, it is necessary to develop a ClO₂ technology that can be easily applied and continuously released for a long period. In this study, a series of ClO₂ self-releasing sachets were developed. First, poly(ether-block-amide) (PEBAX) and polyethylene-glycol (PEG) composite films containing different ratios of citric acid (CA) were prepared using the solution casting method. The as-prepared PEBAX/PEG-CA composite films were evaluated using FT-IR, DSC, and TGA to confirm chemical structure and thermal properties. Subsequently, PEBAX/PEG-CA composite films were designed in the form of a sachet and NaClO₂ powder was transferred into the sachet to achieve a ClO₂ self-releasing system. The ClO₂-releasing behavior of the sachet was investigated by measuring the release amount of the gas using UV-vis. The release amount of ClO₂ increased with increasing CA contents owing to the existence of higher protons (trigger) in the polymer matrix. Further, ClO₂ gas was released for a longer time. Therefore, the as-prepared smart sachet can be tuned according to applications and packaging sizes to serve an optimal sterilization effect.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.2
• /
• pp.19-27
• /
• 2023

This paper is aimed at exploring a multi-racial, multi-ethnic, and multi-cultural trianglulation of Black, White, and Korean American race relations connected to a large-scale disturbance in the 1992 Los Angeles riots. The second generation Korean American Steph Cha's Your House Will Pay (2019) focuses on a social portrait of the racially marginalized beings as Korean immigrant merchants and African American native consumers. This family saga explores issues resulting from racial hierarchy, racialized stereotypes, and historical marginalization in the internalized sociometry of race and class inequality. This work grapples with issues involved in a sociocultural web of racial triangulation under the white dominant structure, and ensuing intergroup conflicts of social minorities in the economic geography of urban space. It opens up civil discussions for transracial, transethnic, and transcultural interactions and coexistence. It ultimately leads to extending young people's minds for a deep understanding of the socioecomonic landscape of racial matrix, and enhancing the cultural literacy for a better awareness of social empathy and the communal respect of life.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.789-798
• /
• 2008

The stiffness method provides a framework to calculate the structural deformations directly from solving the equilibrium state. However, to use the displacement shape functions leads to approximate estimation of stiffness matrix and resisting forces, and accordingly results in a low accuracy. The conventional flexibility method uses the relation between sectional forces and nodal forces in which the equilibrium is always satisfied over all sections along the element. However, the determination of the element resisting forces is not so straightforward. In this study, a new fiber finite element mixed method has been developed for nonlinear anaysis of steel-concrete composite structures in the context of a standard finite element analysis program. The proposed method applies the Newton method based on the load control and uses the incremental secant stiffness method which is computationally efficient and stable. Also, the method is employed to analyze the steel-concrete composite structures, and the analysis results are compared with those obtained by ABAQUS. The comparison shows that the proposed method consistently well predicts the nonlinear behavior of the composite structures, and gives good efficiency.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.27 no.1
• /
• pp.31-44
• /
• 2024

The coastal dune ecosystem is one of the ecosystems under the most development pressure in Korea. Therefore, it is necessary to study the ecological location and related ecological phenomena of coastal dune plants, but related studies are lacking. Through this study, we intend to conduct research on the structure and restoration of dune plants, focusing on the coastal dunes in Jeju Island, which are affected by artificial development pressure and the continuous increase in tourists among many coastal dunes in Korea. Ecosystems of coastal sand dunes for vegetation survey in Jeju Island are selected based on naturalness and preservation. In this study, 23 major coastal dunes on Jeju Island including Udo were selected. In the coastal dunes of Jeju Island, a whole species survey and quadrat survey were carried out. The vegetation survey at study sites were conducted on May to September 2022, when the vegetation is clearly visible. At the survey site, the dune area was identified at the beginning and the plant species were recorded until no more new species appeared. Vegetation survey in the field was performed by 103 quadrat establishments and was conducted using Braun-Blanquet method. A total of 277 species appeared, and the most common species were Vitex rotundifolia and Calystegia soldanella. The frequency of both Vitex rotundifolia and Calystegia soldanella was approximately over 90%. The proportion of woody and herbaceous in all emerging species was 7.2% and 92.8%, respectively. The total number of species found in the quadrat survey was 98. As a result of classifying plant communities based on species dominance in the quadrats, it was analyzed into 30 plant communities. The plant communities that appeared with a frequency of 2 or more on the main island of Jeju were Vitex rotundifolia, Imperata cylindrica var. koenigii, Ischaemum antephoroides, Wedelia prostrata, Elymus mollis, Calystegia soldanella, Artemisia scoparia, and Tetragonia tetragonoides. The DCCA(detrended canonical correspondence analysis) based on the vegetation and environment factor matrix showed that the height and covers of the dominant plant species explain significantly the variation and distribution of coastal sand dune species on Jeju island. Thus, we may propose a plan to restore the coastal dunes of Jeju island as helping colonization and establishment of mainly sand dune native perennials and trees, preserving native plant communities that are declining and preserving present tree strips of Pinus thunbergii, Litsea japonica, Pittosporum tobira and Vitex rotundifolia.

• Journal of Sericultural and Entomological Science
• /
• v.26 no.2
• /
• pp.11-15
• /
• 1984

To save the labour reguired for separation of copulated moth during egg Production, some of the chemicals available at the market were on screen test for easy separation of copulated moth of silkworm. The obtained results are summarized as following. 1. In a separation ratio of copulated moth along with a treating time, TCTFE(Trichloro-trifluoroethane) completely separated the copulated moth in 10 minutes. The combinations of TCTFE plus Acetone (87.5 : 12.5 V/V) and TCTFE plus Acetic acid (50 : 50 V/V) take 25minutes for the complete separation of copulated moth. Use of Acetic acid solution only makes 100% separation of copulated moth in one hour and foully minutes and non$.$treatment shows only 47.5% of separation in three and half hours. On the other hand. There is no statistical significance between TCTFE Plus Acetone and control in the egg productivity. 2. The combination of TCTFE Plus Acetone (87.5 : 12.5 V/V) does not infuluence the egg productivity of the moth, showing 443 grains for an average number of egg per moth out of which 417 grains are for the number of fertilized eggs while control shows 452 grains for an avarage number of egg/moth and 428 grains for the number of fertilized eggs. However a sing1e use of TCTFE and Acetic acid shows less egg productivity and number of ferilized eggs per moth, respectively as compared to those of the control. In particular, a single use of acetic acid makes an increase of number of non-egg prodncible moth and it seems to be brought due to a chemical damage. 3. In a rearing test of the egg laid by the chemical treated moth, there are no differences among the treatments in all of the useful characters of the larvae; larval duration, survival rate, cocoon yield, single cocoon weight, single cocoon shell weight and cocoon shell ratio. In these regards, it is recognized that TCTFE can be practically used for the separation of copulated moth and the combination of TCTFE and Acetone promote its efiectiveness on the separation of copulated moth.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.107-108
• /
• 2008

The spectacular development of AMLCDs, been made possible by a-Si:H technology, still faces two major drawbacks due to the intrinsic structure of a-Si:H, namely a low mobility and most important a shift of the transfer characteristics of the TFTs when submitted to bias stress. This has lead to strong research in the crystallization of a-Si:H films by laser and furnace annealing to produce polycrystalline silicon TFTs. While these devices show improved mobility and stability, they suffer from uniformity over large areas and increased cost. In the last decade we have focused on microcrystalline silicon (${\mu}c$-Si:H) for bottom gate TFTs, which can hopefully meet all the requirements for mass production of large area AMOLED displays [1,2]. In this presentation we will focus on the transfer of a deposition process based on the use of $SiF_4$-Ar-$H_2$ mixtures from a small area research laboratory reactor into an industrial gen 1 AKT reactor. We will first discuss on the optimization of the process conditions leading to fully crystallized films without any amorphous incubation layer, suitable for bottom gate TFTS, as well as on the use of plasma diagnostics to increase the deposition rate up to 0.5 nm/s [3]. The use of silicon nanocrystals appears as an elegant way to circumvent the opposite requirements of a high deposition rate and a fully crystallized interface [4]. The optimized process conditions are transferred to large area substrates in an industrial environment, on which some process adjustment was required to reproduce the material properties achieved in the laboratory scale reactor. For optimized process conditions, the homogeneity of the optical and electronic properties of the ${\mu}c$-Si:H films deposited on $300{\times}400\;mm$ substrates was checked by a set of complementary techniques. Spectroscopic ellipsometry, Raman spectroscopy, dark conductivity, time resolved microwave conductivity and hydrogen evolution measurements allowed demonstrating an excellent homogeneity in the structure and transport properties of the films. On the basis of these results, optimized process conditions were applied to TFTs, for which both bottom gate and top gate structures were studied aiming to achieve characteristics suitable for driving AMOLED displays. Results on the homogeneity of the TFT characteristics over the large area substrates and stability will be presented, as well as their application as a backplane for an AMOLED display.

• Korean Chemical Engineering Research
• /
• v.50 no.6
• /
• pp.1068-1075
• /
• 2012

Poly(butylene terephthalate) (PBT)/Nylon6,12 core/shell micro fiber were prepared by extrusion molding. To investigate their optimum extrusion conditions, compatibility of PBT/Nylon6,12 blend micro fiber in conformity to their weight ratio and manufacture temperature was explored with SEM morphology and DSC. The alterations in their mechanical properties by extrusion speed were compared and analyzed through a UTM. In comparison with SEM figures, the domain sizes of Nylon6,12 were gradually declined by increasing the extrusion temperature of blends. Furthermore, according to these SEM images, the phase separation between Nylon6,12 domain and PBT matrix became indistinct with increasing of weight percentage of Nylon6,12. In case of DSC, the boundaries of two peaks were almost disappeared when increasing the extrusion temperature and also intervals of each two melting peaks became narrow as increasing the Nylon6,12 ratio. The mechanical properties including tensile strength, elongation, flexural strength and flexural modulus were increased as the increase in the extrusion temperature until $260^{\circ}C$. However, the mechanical properties were actually deteriorated over $260^{\circ}C$. The tensile strength, elongation, flexural strength and flexural modulus at $260^{\circ}C$ were 560 $kg_f/cm^2$, 220%, 807 $kg_f/cm^2$ and 22,146 $kg_f/cm^2$, respectively. These values are more than intermediate values of mechanical properties of PBT and Nylon6,12. These results mean that there is compatibility between PBT and Nylon6,12. Based on the extrusion conditions that produced optimum compatibility of blend, as a result, our group obtained micro fibers with the core/shell structure.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.21 no.2
• /
• pp.131-136
• /
• 1985

The calculation of the resulting fluid motion is an important problem of ship hydrodynamics. For a partially immersed body the condition of constant pressure at the free surface can be linearized. The resulting linear boundary-value problem for the velocity potential is the Neumann-Kelvin problem. The two-dimensional Neumann-Kelvin problem is studied for the half-immersed circular cylinder by Ursell. Maruo introduced a slender body approach to simplify the Neumann-Kelvin problem in such a way that the integral equation which determines the singularity distribution over the hull surface can be solved by a marching procedure of step by step integration starting at bow. In the present pater for the two-dimensional Neumann-Kelvin problem, it has been suggested that any solution of the problem must have singularities in the corners between the body surface and free surface. There can be infinitely many solutions depending on the singularities in the coroners.

• Applied Microscopy
• /
• v.38 no.4
• /
• pp.293-306
• /
• 2008

The essential factor of acute respiratory distress syndrome (ARDS), an acute lung injury accompanied commonly by sepsis syndrome is accumulation of neutrophils in lung tissue. The study attempted to confirm whether a lung injury would be decreased with the anti-inflammatory effect of germanium by the treated germanium prior to the development of ARDS and whether nitric oxide influence in suppressing a lung injury. Test groups were divided in the following structure for experiment; CON that has been administered with sodium chloride to airway, LPS administered with endotoxin for 5 hours in the same amount and 5 hours of endotoxin administered Ge+LPS following 1 hours of pre-treated germanium. The result of a test using experimental animals, infilteration of neutrophils (p<0.001) in bronchoalveolar lavage fluid (BALF) was significantly decreased, the structure of lung tissue was preserved relatively well, and much neutrophils with distinct positive were observed on tunel staining which showed increase of apoptotic neutrophils in the pre-treated germanium group compare to the endotoxin administrated group. In observation of ultrastructural changes of cell in BALF, phagocytic alveolar macrophage was increased in alveolar space, the nucleus of most engulfed neutrophils were condensed, and some apoptosis neutrophils appears to be DNA fragmentation and effacement of cellular organelles were found in intercellular matrix in the pre-treated germanium group. However, the nitric oxide showed increase in all the groups excluding CON, and the nitric oxide effect such as degranulation diminishing of mast cells and apoptosis increase of neutrophils in the pre-treated group only. The situation appears that there was change in internal environment of the experimental animal by the pre-treated germanium before the nitric oxide is produced and the anti-inflammatory effect activated the pre-processed germanium by nitric oxide which activated following the change. Therefore, the nitric oxide created from macrophage in accordance with the pre-treated germanium appears to influence in alleviating a lung injury. Accordingly, acute lung injury is alleviated by the anti-inflammatory effect of germanium such as inhibition of neutrophils migration, induction of neutrophil apoptosis and increase of phagocytic function of phagocyte, and the nitric oxide produced from activated macrophage by germanium would influence in suppressing a lung injury.

• Journal of the Korean Geographical Society
• /
• v.41 no.2 s.113
• /
• pp.150-167
• /
• 2006

This study was conducted to determine the pedogenesis of dense subsurface horizons (denoted either Bx or Bd) observed within closed depressions and in toeslope positions at loess-covered glacial tillplains in southern Wisconsin. Some of these dense subsurface horizons, especially those occurring within depressions, show a close morphological resemblance to fragipans elsewhere, even though the existence of fragipans has not been previously reported in southern Wisconsin. The spatial occurrence of fragipans was first examined over the landscape to characterize general soil-landscape relationships. Detailed physico-chemical and micromorphological analyses were followed to investigate the development of fragipans within a closed depression along a catenary sequence. The formation of fragipans at the study site is a result of sequential processes of physical ripening and accumulation of colloidal materials. A very coarse prismatic structure with a closely packed soil matrix was formed via physical ripening processes of loess deposited in small glacial lakes and floodplains that existed soon after the retreat of the last glacier. The physically formed dense horizons became hardened by the accumulation of colloidal materials, notably amorphous Si. The accumulation intensity of amorphous Si varies with mass balance relationships, which are governed by topography and local drainage conditions. Well-developed Bx horizons evolve at closed depressions where net accumulation of amorphous Si occurs, but the collapsed layers remain as Bd horizons at other locations where soluble Si has continuously been removed downslope or downvalley. Hydromorphic processes caused by the presence of fragipans are degrading upper parts of the prisms, resulting in the formation of an eluvial fragic horizon (Ex).