• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.25-32
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• 2021

In this paper, the Magneto-Electric(ME) dipole array antenna with dual-polarization in the X-Band is proposed and it is implemented and measured. The proposed array antenna is composed of 32 single ME dipole antenna and a Teflon PCB. 1 × 1 ME dipole antenna is implemented dual-polarization by radiating vertical polarization and horizontal polarization from two pairs of radiators. 2-port feeding structures are realized by lamination process using LTCC. And, each port independently feeds the radiator through a Γ-shaped feeding strip with isolation between ports. The Teflon PCB used in the antenna array has a 4-layer structure, and 2-port is fed through the top and bottom layers. The λ_g/4 transformer is applied to the transmission line of the Teflon PCB for impedance matching of the arrayed antenna and the Teflon PCB, and the optimal parameters are obtained through simulation. The measured maximum antenna gains of port 1 was 18.2 dBi, Cross-pol was 1.0 dBi. And the measured maximum antenna gains of port 1 was 18.1 dBi, Cross-pol was 3.2 dBi.

• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.149-156
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• 2021

A kraft recovery boiler produces steam for power generation by the combustion of black liquor from the kraft pulping process. Since saturated steam became superheated in a superheater above the furnace, it is important to increase the heat exchange efficiency for the superheated steam production and power generation. A nose arch at the bottom of the superheater is important for blocking radiation from the furnace which causes corrosion of the superheater. But the nose arch is the main reason for creating a recirculation region and then decreasing the heat exchange efficiency by holding cold flue gas after the heat transfer to saturated steam. In this study, the size of recirculation region and the temperature of flue gas at the outlet were analyzed by the nose arch structure using computational fluid dynamics (CFD). As a result, when the nose arch angle changed from 106.5° (case 1) to 150° (case4), the recirculation region of flue gas decreased and the heat exchange efficiency between the flue gas and the steam increased by 10.3%.

• Journal of Marine Life Science
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• v.5 no.1
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• pp.25-33
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• 2020

The Asan Bay, which has semi-diurnal tide with macro-tidal range, is affected by both freshwater discharge from the sluice gates in the sea dikes and tidal seawater inputs from the Yellow sea. Understanding water quality change in response to tides is important since tides can impact the short-term variations in physical and chemical water properties as well as the response of biological properties. The diel variations in water quality were seasonally investigated at 2 hour intervals from a fixed station in the Asan Bay. In the results, water temperature and salinity consistently fluctuated in phase or out of phase with tidal height. Especially salinity was positively correlated with tidal height. The concentrations of total suspended solids were higher in the bottom water than in the surface and fluctuated greatly over the tidal cycle recording higher values at low tide than at high tide. Nitrite+nitrate levels also fluctuated out of phase with tidal height and correlated negatively with tidal height. Other nutrients also showed a similar pattern. The pattern was distinct in July when freshwater was discharged before the field sampling. The concentrations of organic materials, total nitrogen and total phosphorus greatly fluctuated over the tidal cycle and were generally out of phase with tidal height. Most materials except particulate organic forms were correlated with salinity indicating that freshwater inputs were sources for the materials similarly to the dissolved inorganic nutrients. The results suggest that water quality (except dissolved oxygen and pH) and nutrients including organic materials was largely affected by tides in the Asan Bay.

• Smart Structures and Systems
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• v.24 no.6
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• pp.769-781
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• 2019

Dynamic displacement response of civil structures is an important index for in-construction and in-service structural condition assessment. However, accurately measuring the displacement of large-scale civil structures such as high-rise buildings still remains as a challenging task. In order to cope with this problem, a vision-based system with the use of industrial digital camera and image processing has been developed for long-distance, remote, and real-time monitoring of dynamic displacement of supertall structures. Instead of acquiring image signals, the proposed system traces only the coordinates of the target points, therefore enabling real-time monitoring and display of displacement responses in a relatively high sampling rate. This study addresses the in-situ experimental verification of the developed vision-based system on the Canton Tower of 600 m high. To facilitate the verification, a GPS system is used to calibrate/verify the structural displacement responses measured by the vision-based system. Meanwhile, an accelerometer deployed in the vicinity of the target point also provides frequency-domain information for comparison. Special attention has been given on understanding the influence of the surrounding light on the monitoring results. For this purpose, the experimental tests are conducted in daytime and nighttime through placing the vision-based system outside the tower (in a brilliant environment) and inside the tower (in a dark environment), respectively. The results indicate that the displacement response time histories monitored by the vision-based system not only match well with those acquired by the GPS receiver, but also have higher fidelity and are less noise-corrupted. In addition, the low-order modal frequencies of the building identified with use of the data obtained from the vision-based system are all in good agreement with those obtained from the accelerometer, the GPS receiver and an elaborate finite element model. Especially, the vision-based system placed at the bottom of the enclosed elevator shaft offers better monitoring data compared with the system placed outside the tower. Based on a wavelet filtering technique, the displacement response time histories obtained by the vision-based system are easily decomposed into two parts: a quasi-static ingredient primarily resulting from temperature variation and a dynamic component mainly caused by fluctuating wind load.

• Journal of Plant Biotechnology
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• v.49 no.3
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• pp.222-229
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• 2022

Apples are the most grown fruit crops in the fruit industry of Korea. However, virus or viroid infection such as apple mosaic virus (ApMV), apple stem grooving capillovirus (ASGV), apple stem pitting virus (ASPV), apple chlorotic leaf spot virus (ACLSV), apple scar skin viroid (ASSVd) causes fruit yield reduction and poor fruit quality. Therefore, in this study, we examined to established an efficient virus-free system to eliminate the most infected ASGV virus in domestic apple orchard. We investigated that the shoot growth rate and the virus removal rate in ASGV infected potted apples that were treated with heat treatment in a growth chamber (constant temperature/humidity device) maintained at 36℃, 38℃ and 40℃ for 4 weeks. Here we found that the shoot growth rate was the highest in the heat treatment group (36℃) and the virus was removed in the middle and top of the shoot but not in the bottom. The virus was did not removed in the 38℃ and 40℃ heat treatment group in all section of shoots, and the heat treatment group (40℃) died after 4 weeks of heat treatment without growth of shoots. We performed in vivo shoot-tip grafting using the shoot-tip of potted apple heat-treated at 36 ℃, and we also investigated the viability and virus removal rate, which showed 94% viability and 20% virus removal rate. Collectively, our results suggest that it would be possible to produce the virus-free apple plants through heat treatment and shoot-tip grafting.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.384-389
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• 2021

This study was conducted on October 23, 2020 at the Cheongpyeong Reservoir located in Seorakmyeon, Gapyeong-gun, Gyeonggi-do, and analyzed the horizontal and vertical distribution patterns of fish based on data obtained using fishfinder. The total surface area of fishfinder survey conducted was 782,853 m², and where the water depth (WD) ranges from 10 m to 12 m is widest which 31.7% of total surface area. As a result of the heat map analysis, fish density was highest at right bank under the Gapyeong-bridge, but there was no specific pattern in horizontal distribution of fish. As a result of vertical distribution of fish analysis, 86.6% of fishes are observed at below 6 m of the fish depth (FD, distance from water surface to fish). As a result of the relative height (RH, water depth-distance from bottom to fish ratio) analysis, there was a tendency that fishes are distributed in near surface area more as the WD increased. This tendency could have various reasons such as water temperature gradient along the water depth, and further studies are required for detailed explanation.

• Journal of Marine Life Science
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• v.1 no.1
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• pp.18-24
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• 2016

Since April 2012, doctor fish in the breeding tank and in the quarantine tank in Hanwha Aquaplanet Yeosu Aquarium have been dying, accompanied by diffuse bleeding around the mouth, in the chin, and at the bottom of the abdomen. In this study, the cause of death would be examined through the bacteriological study of doctor fish and the rearing water quality in the aquarium. The water quality and the bacterial counts of the rearing water in the exhibit tank and in the quarantine tank were analyzed once a week, starting from August to November 2014. Water quality was measured based on the following data: temperature was in the range of 24.5~26.8℃, pH at 6.77~7.94, DO at 6.15~8.61 ppm, ammonia at 0~0.93 ppm, nitrite at 0.009~0.075 ppm, and nitrate at 1.1~40.9 ppm. Studies revealed that the differences in these water quality factors were not related to the death of doctor fish. Bacterial counts in the rearing waters of Garra rufa slightly increased to 10³~10⁴ CFU/ml, just before the death of the doctor fish. Twelve strains of bacteria were isolated from the dead fish and rearing waters. The isolates were identified as Aeromonas veronii, Citrobacter freundii, Pseudorhodoferax aquiterrae, Shewanella putrefaciens, and Vibrio anguillarum on the basis of 16S rRNA gene sequences. The most dominant species was C. freundii, which showed medium sensitivity to florfenicol and norfloxacin, and was resistant to amoxacillin, doxycycline, oxytetracycline, tetracycline, and trimethoprim. Ten isolates were confirmed to be pathogenic to the doctor fish. Doctor fish infected with C. freundii and S. putrefaciens showed high mortality in the experimental groups. These results indicate that the variation in bacterial numbers in the rearing water was related to the death of doctor fish. C. freundii and S. putrefaciens were directly implicated in causing the death of doctor fish in the aquarium.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.513-520
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• 2023

Korean melon (Cucumis melo L.) is an environment in which most farming work can affect the increase in musculoskeletal diseases, and the stems are attracted to the ground in order to grow no-heating cultivation. In this study, growth and productivity were compared according to the type of high-bed. The narrower the surface area at the bottom of the high-bed, the faster the initial growth, which was advantageous. The bed is which the height if 70 cm, the surface temperature has risen due to the increase in direct solar radiation inflow since April, requiring side light blocking to block the inflow of solar radiation. In terms of fruit quality, the 200 cm width treatment had higher fruit sugar content and better hardness than the 160 cm treatment. From April to September, the total yield was 6.8 kg/plant of treatment A, 8.7 kg/plant of treatment B, 5.8 kg/plant of treatment C, treatment B mainly 50% higher than treatment C, and 27% higher than treatment A. Therefore, the bed form suitable for Korean melon high bed is 200 cm wide, 40 cm high between the surface and the bed, and the surface of the passage between the beds is 30cm high from the ground to the bed.

• The Korean Journal of Malacology
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• v.23 no.1
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• pp.1-8
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• 2007

The influence of individual size, sediment, gain size, water temperature, salinity and air exposure on burrowing rate was investigated in order to obtain the basic biological data on applying shellfish farm for a sustainable production of ark shell, Scapharca broughtonii (Schrenk). The burrowing rate on individual size 300 minutes after starting the experiment was the highest in the shell length $16.3\;{\pm}\;1.2\;mm$, 97.7%. The highest burrowing rates were 97.0% in $12.8\;{\pm}\;0.8\;mm$, 96.7% in $9.2\;{\pm}\;1.0\;mm$, and 96.3% in $5.9\;{\pm}\;0.7\;mm$. The clams over 6 mm of shell length had burrowing ability and the burrowing rate was not related to the shell size. The burrowing rate depending on the kind of grain at the bottom after 300 minutes was the highest, 98.3%, in the mixture of sand and silt with a ratio of 75:25. The rates were 98% in silt (100%), 97.3% in mixture sand and silt with a ratio of 50:50, 97.3% in sand and silt ratio of 25:75, and 86.3% in sand (100%) in this specific order. On grain size of the soil in the seafloor, the burrowing rates after 300 minutes was at its highest in the group of sand in pore size 1 mm with 85.0%, and the $12\;{\mu}m$ to 1 mm in the grain size was fitted to burrowing of artificial seed. In the case of water temperature, the burrowing rates were at its highest after 300 minutes. In $30^{\circ}C$ group, the rate was 96.7% and in $25^{\circ}C$ and $20^{\circ}C$, 90.0%. The rates decreased as the water temperature decreased below $15^{\circ}C$. The burrowing rates on salinity were the highest in 30 psu with 93.3% and at 15 psu and below, there was no noticeable change in the burrowing rate. On air exposure, the burrowing rates after 300 minutes were the highest in 1 hour with 93.3%, and remarkably decreased as air exposure time is longer after 12 hours of air exposure.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.459-467
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• 2016

Due to the limited areal space for installation, borehole heat exchangers (BHEs) at depths deeper than 300 m are considered for geothermal heating and cooling in the urban area. The deep vertical closed-loop BHEs are unconventional due to the depth and the range of the typical installation depth is between 100 and 200 m in Korea. The BHE in the study consists of 50A (outer diameter 50 mm, SDR 11) PE U-tube pipe in a 150 mm diameter borehole with the depth of 300 m. In order to compensate the buoyancy caused by the low density of PE pipe ($0.94{\sim}0.96g/cm^3$) in the borehole filled with ground water, 10 weight band sets (4.6 kg/set) were attached to the bottom of U-tube. A thermal response test (TRT) and fundamental basic surveys on the thermophysical characteristics of the ground were conducted. Ground temperature measures around $15^{\circ}C$ from the surface to 100 m, and the geothermal gradient represents $1.9^{\circ}C/100m$ below 100 m. The TRT was conducted for 48 hours with 17.5 kW heat injection, 28.65 l/min at a circulation fluid flow rate indicates an average temperature difference $8.9^{\circ}C$ between inlet and outlet circulation fluid. The estimated thermophysical parameters are 3.0 W/mk of ground thermal conductivity and 0.104 mk/W of borehole thermal resistance. In the stepwise evaluation of TRT, the ground thermal conductivity was calculated at the standard deviation of 0.16 after the initial 13 hours. The sensitivity analysis on the borehole thermal resistance was also conducted with respect to the PE pipe diameter and the thermal conductivity of backfill material. The borehole thermal resistivity slightly decreased with the increase of the two parameters.