• Journal of Convergence for Information Technology
• /
• v.8 no.6
• /
• pp.187-192
• /
• 2018

This thesis is about the study of inverter terminal boxes in a explosion proof type exhaust fan that can control wind volume and operating time. In Korea, there is no ventilator to adjust the amount of wind and operating time when working in poor conditions. The purpose of the project is to create a explosion terminal box that can control the operating time and wind speed of a suitable explosion ventilator in hazardous environments. The two explosion-proof switches allow the operation time to be driven 1 hour, 3 hours and continuous time, and the speed of the induction motor rotation was set in 3 stages at 2000 rpm, 2600 rpm and 3000 rpm to control the volume. The tested motor used a half-horsepower barrier three-phase induction motor and a full-bridge inverter to set the desired flow rate and operating time.

• Journal of Sensor Science and Technology
• /
• v.10 no.5
• /
• pp.304-313
• /
• 2001

In this research, we investigate wet-etching properties of GaAs in $NH_4OH-H_2O_2-H_2O$, and develop the fabrication method of GaAs microstructures with rectangular cross section using (001) GaAs substrate. For obtaining wet-etching properties with respect to crystallographic orientation, the etch rates and cross-section etch profiles of (001) GaAs with 16 different compositions and the undercut rates with 5 different compositions are measured using $NH_4OH-H_2O_2-H_2O$ mixed solutions. From these experimental data, a new GaAs micromachining method in bulk (001) GaAs is proposed, and used to fabricate a released microbridges with a rectangular cross section. The developed GaAs micromachining method can be very useful for low-loss, highly-tunable capacitors for RF components and for integration with GaAs optical components.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.135-141
• /
• 2020

The silica aerogels with benzene-bridged were designed to have uniform network structure, ordered pore structure, improved mechanical properties and excellent textural properties. Adding organic to enhance the mechanical properties of silica aerogels is a common method, but textural properties of aerogels with organic are reduced due to the organic-inorganic phase separation. In this paper, we use a simple and low-cost method to increase mechanical properties while maintaining textural properties of SiO2 aerogels. Two types of benzene-bridged precursors were prepared to study the effect of the number of hydroxyl band on the textural and mechanical properties. The porous silica aerogel was prepared by a simple, cost effective and pollution-free sol-gel method. This method does not require additional silylating reagents. The benzene-bridged silica aerogel samples prepared had excellent textural properties, high specific surface area (1,326 ㎡/g), porous structure and hydrophobicity (>140°). The mechanical strength of 2T4 is more than 5 times that of pure silica aerogel.

• Korean journal of applied entomology
• /
• v.59 no.4
• /
• pp.383-391
• /
• 2020

The vertical distribution and dispersion of the two-spotted spider mite, Tetranychus urticae and its predator, Phytoseiulus persimilis, were investigated within and between green pepper plants. We also tested the effect of an artificial bridge with threads on dispersal of P. persimilis between the plants. The extent of spread of T. urticae depended on its infested density and location. When 10 adults of T. urticae were inoculated on upper leaf, they stayed on the upper leaf until 5 days after inoculation. However, when 100 adults were inoculated on an upper leaf, they dispersed to the lower leaf within a day. In condition that 10 adults of T. urticae were inoculated on the lower leaf, they started to move toward upward within a day. In the absence of T. urticae, P. persimilis tended to move to the leaves where T. urticae was present when both T. urticae and P. persimilis were inoculated together within a plant. An artificial bridge with threads between two plants was helpful to disperse P. persimilis to neighboring plants. Therefore, it would be expected that the dispersal of P. persimilis can be promoted by supplying the artificial bridges among plants and by narrowing the distances between plants.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.7 s.337
• /
• pp.41-48
• /
• 2005

We design and fabricate 3-dB tandem directional coupler using the coplanar waveguide structure which is applicable to balanced amplifiers and mixers for 60 GHz wireless local area network system. The coupler comprises the multiple-sectional parallel-coupled lines to facilitate the fabrication process, and enable smaller device size and higher directivity than those of the conventional 3-dB coupler employing the edge-coupled line. In this study, we adopt the structure of two-sectional parallel-coupled lines of which each single-coupled line has a coupling coefficient of -8.34 dB and airbridge structure to monolithically materialize the uniplanar coupler structure instead of using the conventional multilayer or bonded structure. The airbridge structure also supports to minimize the parasitic components and maintain desirable device performance in V-band (50$\~$75 GHz). The measured results from the fabricated couplers show couplings of 3.S$\~$4 dB and phase differences of 87.5$^{\circ}{\pm}1^{\circ}$ in V-band range and show directivities higher than 30 dB at a frequency of 60 GHz.

• Journal of Plant Biotechnology
• /
• v.45 no.4
• /
• pp.392-399
• /
• 2018

Fruits of 10 cultivars ('Blue Gold', 'Brigitta', 'Coville', 'Duke', 'Nelson', 'North Blue', 'Rancocas', 'Sierra', Sunrise, and 'Weymouth') of blueberries (Vaccinum corymbosun) were analyzed for characteristics, contents of total phenolic compounds and flavonoids and antioxidant activity in this study. Fruit weights ranged from 0.83 to 1.88 g. Total soluble solids concentration varied from 9.7 in 'Duke' to $16.6^{\circ}Brix$ in 'Sierra' with titratable acidities of 0.94 % in 'Sunrise' and 1.75% in 'Brigitta'. There are relatively high contents in 'North Blue' ($23.75mg\;GAE{\cdot}g^{-1}\;FW$) and low contents in 'Coville' ($17.15mg\;GAE{\cdot}g^{-1}\;FW$) in total phenolic compounds. Contents of total phenolic compounds were high in 'Nelson'($14.1mg\;QE{\cdot}g^{-1}\;FW$) and low in 'Duke' ($10.1mg\;QE{\cdot}g^{-1}\;FW$). Analysis of antioxidant activity of blueberry fruits showed that there were high acitiviites of ABTS+ radical scavenging in 'Rancoccas' (82.2%), 'Bluegold' (79.6%), and 'Nelson' (77.8%), and high activities of DPPH radical scavenging in 'Rancocca' (76.0%), and high in hydroxy radical scavenging in 'Nelson' (73.0%). Quantification analysis method of qualitative data showed that 'Bluegold', 'Nelson', 'Northblue', and 'Rancocas' had high contents of phenol and flavonoid compounds, and activity antioxidants of berries. Blueberry cultivars selected by statistical quantification analysis can be utilized as valuable genetic resources for breeding of blueberry with high antioxidant activities in the future.

• Journal of the Economic Geographical Society of Korea
• /
• v.26 no.4
• /
• pp.375-390
• /
• 2023

This study examined the genesis process and competitiveness determinants of overseas bio-industrial clusters. The bio industry is a promising new industry that major countries around the world are paying attention to because it can be applied to various industries and can create high added value by combining artificial intelligence and information and communication technology. In addition, the importance of clusters is emphasized in that it requires connection and cooperation with various stakeholders. However, compared to this importance and interest, related research in Korea is somewhat insufficient. In particular, overseas case studies are also overly biased toward a few leading clusters, and tend to produce policies and development plans that do not correspond to domestic local conditions. To alleviate this problem, this study looked at the birth and growth process of the BioHealth Capital Region in the United States, Cambridge Cluster in the United Kingdom, and Medicon Valley in Denmark and Sweden. Through this, we aim to enrich related case studies that were lacking, identify the determinants of competitiveness of each cluster, and present implications for the creation and development of domestic bio industry clusters.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.33 no.3
• /
• pp.16-37
• /
• 2015

As a result of analyzing the forming and the transformations of Seokjojeon Hall garden by linking it to the changes of Deoksugung Palace influenced by the social atmosphere, the Seokjojeon garden can be classified into four phases. The first phase starts from 1896 to 1914. Gyeongungung was built in the late 19th century(1896-1897) as an official palace and Junghwajeon Hall and Seokjojeon Hall was built for Gojong. J.M.Brown was in charge of the construction of Seokjojeon in the beginning but H.W.Davidson saw the end also set up the garden. In the process of forming the garden the incorporating of Dondeokjeon Hall and the demolishing of the west wing corridors of Junghwajeon Hall occurred. At this phase of the garden a statue of an eagle was put up in the garden but was soon taken down. The shape of the garden was quiet simple with a central axial pathway, a round assorted flower bed placed in front of Seokjojeon Hall. The second phase starts from 1915 to 1932 which lasted for 17 years. At the last years of the Great Han Empire the duties of Gungnaebu(宮內府) was transferred to Leewangjik(李王職) in 1911 and a research on the existing buildings was done by Jujeonkwa(主殿課) in 1915. According to the research drawings, the garden still maintained the axial pathway formed in the previous phase but the garden had an asymmetric form. The flower bed was formed in a round shape and an open-knot technique and boundary plantation was applied to the garden. The third phase starts from 1933 to 1937 and is the period when Seokjojeon Hall was made public. By the year of 1932 many buildings of Deoksugung Palace had been demolished in the preparation of the opening of Seokjojeon Hall as a permanent exhibition hall. The central axial pathway still remained in the new garden and added a pond with a turtle statue in the center. The fourth phase starts from 1938 until the liberation from Japan and is the period when Deoksugung Palace became a park. Yi Royal-Family Museum was built and linked to Seokjojeon Hall with a bridge and the garden transformed into a sunken garden. The garden adopted a fountain and a pagora. Despite the minor changes in the after years the garden still posses most of its form from the fourth phase. As we can see the current garden of Seokjojeon Hall is not the same as the initial garden and therefor the importance of this study lies in the fact that modifications to the statements regarding to Seokjojeon Hall garden should be made.