• Korean Journal of Ichthyology
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• v.33 no.2
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• pp.74-83
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• 2021

Distribution status, habitat characteristics, and extinction threat evaluation of the endangered species, Brachymystax lenok tsinlingensis were investigated in 2015 and 2019. Historical distribution reports of B. l. tsinlingensis were divided into before 1990, 1997~2006, 2000~2011, and 2010~2019. Among the 150 sampling sites investigated during the study period, number of individuals of B. l. tsinlingensis were collected 542 individuals from 67 sites. The streams inhabited of B. l. tsinlingensis were Naerincheon (11 stations), Odaecheon (11 stations), Bukcheon (10 stations), Bangtaecheon (8 stations), Songjeongricheon (4 stations), Suipcheon (3 stations), Inbukcheon (3 stations), Hyeondongcheon (3 stations) etc. The main habitat of B. l. tsinlingensis was upstream of the river with a high altitude of more than 400 m, 4~20 m water flow width, 1~2 m water depth, and high ratio (70~80%) boulder bottoms. The main reasons for the decline in population size were assumed as river works, construction of reservoirs and bridges, discharge of contaminated water into the river, the inflow of summer vacationers, and weir. Compared to our results there exists evidence that states a 20.7% reduction in occupancy within 10 years, in a small appearance range (7,732 km²) and occupancy area (268 km²), number of disconnected locations (15 locations), and a decline in habitat quality. Therefore, B. l. tsinlingensis is now considered as Near Threatened (NT) based on the results (Near meets VU A2acd, B1b(i,ii,iii)+B2b(i,ii,iii)) of IUCN Red List categories and criteria.

• Korean Journal of Ichthyology
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• v.34 no.1
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• pp.34-43
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• 2022

A distribution survey was conducted from March to August 2021 to evaluate the distribution status, habitat characteristics, and threat of extinction of the Korean cold-water fish Ladislabia taczanowskii Dybowski (Cypriniformes, Cyprinidae). Historical distribution reports were divided into 1997~2005, 2006~2012, 2013~2019, and distribution surveyed 169 sampling sites, and 1,040 individuals were collected from 72 sites. Areas where the habitat was confirmed were Namhan River (27 stations), Han River (17 stations), Bukhan River (16 stations), Samcheok Osipcheon (4 stations), Yeongokcheon (3 stations), Gangneung Namdaecheon (2 stations), Jeoncheon (1 station), Chucheon (2 stations). The main habitat of L. taczanowskii was upstream of the river with a high altitude of more than 300 m, 2~30 m water flow width, 0.3~1.5 m water depth, and high ratio (50~90%) boulder bottoms. The main reasons for the decline in population size were assumed as river works, construction of reservoirs and bridges, discharge of contaminated water into the river, the inflow of summer vacationers, and weir. Compared to our results there exists evidence that states a 36.1% reduction in occupancy within 10 years, in a small appearance range (7,820 km²) and occupancy area (288 km²), number of disconnected locations (19 locations), and a decline in habitat quality. Therefore, L. taczanowskii is now considered as Vulnerable (VU) based on the results (VU A2ac, Near meets B1b (i, ii, iii)+B2b (i, ii, iii)) of IUCN Red List categories and criteria. Lastly, the conservation plan of Ladislabia taczanowskii was discussed.

• Wind and Structures
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• v.34 no.1
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• pp.115-125
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• 2022

The high-Reynolds number flow around a rectangular cylinder, having streamwise to crossflow length ratio equal to 5 is analyzed in the present paper. The flow is characterized by shear-layer separation from the upstream edges. Vortical structures of different size form from the roll-up of these shear layers, move downstream and interact with the classical vortex shedding further downstream in the wake. The corresponding mean flow is characterized by a recirculation region along the lateral surface of the cylinder, ending by mean flow reattachment close to the trailing edge. The mean flow features on the cylinder side have been shown to be highly sensitive to set-up parameters both in numerical simulations and in experiments. The results of 21 Large Eddy Simulations (LES) are analyzed herein to highlight the impact of the lateral mean recirculation characteristics on the near-wake flow features and on some bulk quantities. The considered simulations have been carried out at Reynolds number Re=DU_∞/ν=40 000, being D the crossflow dimension, U_∞ the freestream velocity and ν the kinematic viscosity of air; the flow is set to have zero angle of attack. Some simulations are carried out with sharp edges (Mariotti et al. 2017), others with different values of the rounding of the upstream edges (Rocchio et al. 2020) and an additional LES is carried out to match the value of the roundness of the upstream edges in the experiments in Pasqualetto et al. (2022). The dimensions of the mean recirculation zone vary considerably in these simulations, allowing us to single out meaningful trends. The streamwise length of the lateral mean recirculation and the streamwise distance from the upstream edge of its center are the parameters controlling the considered quantities. The wake width increases linearly with these parameters, while the vortex-shedding non-dimensional frequency shows a linear decrease. The drag coefficient also linearly decreases with increasing the recirculation length and this is due to a reduction of the suctions on the base. However, the overall variation of C_D is small. Finally, a significant, and once again linear, increase of the fluctuations of the lift coefficient is found for increasing the mean recirculation streamwise length.

• Ecology and Resilient Infrastructure
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• v.10 no.3
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• pp.64-72
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• 2023

Biopolymer is a versatile material used in food processing, medicine, construction, and soil reinforcement. 𝛽-glucan is one of the biopolymers that improves the soil water content and ion adsorption in a drought or toxic metal contaminated land for plant survival. We analyzed drought stress damage reduction in sweet potatoes (Ipomoea batatas L. cv. Sodammi) by measuring the growth and major protein expression and activity under 𝛽-glucan soil amendment. The result showed that sweet potato leaf length and width were not affected by drought stress for 14 days, but sweet potatoes grown in 𝛽-glucan-amended soil showed an effect in preventing wilting caused by drought in phenotypic changes. Under drought stress, sweet potato leaves did not show any changes in electrolyte leakage, but the relative water content was higher in sweet potatoes grown in 𝛽-glucan-amended soil than in normal soil. 𝛽-glucan soil amendment increased the expression of plasma membrane (PM) H⁺-ATPase, but it decreased the aquaporin PIP2 (plasma membrane intrinsic protein 2) in sweet potatoes under drought stress. Moreover, water maintenance affected the PM H⁺-ATPase activity, which contributed to tolerance under drought stress. These results indicate that 𝛽-glucan soil amendment improves the soil water content during drought and affects the water supply in sweet potatoes. Consequently, 𝛽-glucan is a potential material for maintaining soil water contents, and analysis of the major PM proteins is one of the indicators for evaluating the biopolymer effect on plant survival under drought stress.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.4
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• pp.276-284
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• 2023

After tooth extraction, alveolar bone is resorbed over time. Loss of alveolar bone and reduction of upper soft tissue poses difficulties in future implant placement and long-term survival of the implant. This case report focuses on increasing the soft and hard tissues at the implant placement site by using alveolar ridge augmentation and a xenogeneic collagen matrix as a soft tissue substitute in an extraction socket affected by periodontal disease. In each case, the width of the alveolar bone increased to 6 mm, 8 mm, and 4 mm, and regeneration of the interdental papilla around the implant was shown, as well as buccal keratinized gingiva of 4 mm, 6 mm, and 4 mm, respectively. Enlarged alveolar bone facilitates implant surgery, and interdental papillae and keratinized gingiva enable aesthetic prosthesis. This study performed alveolar ridge augmentation on patients with extraction sockets affected by periodontal disease and additionally used soft tissue substitutes to provide a better environment for implant placement and have positive effects for aesthetic and predictive implant surgery.

• Journal of Bio-Environment Control
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• v.33 no.1
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• pp.37-44
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• 2024

This study was conducted to validate the growth and productivity of cucumber hydroponics using coir as the medium, different types of nutrient solutions and formal methods, in order to select the most efficient cultivation method. The nutrient solutions consisted of culture solution (S) and raw water (W), the planting methods were rockwool cube seedlings (RC), rockwool plug seedlings (RP), and slab directly seedlings (DS). The reference date was set the sowing date. The initial growth showed a significant increase in the culture solution treatment, the differences among treatments decreased as the growth period lengthened. There was no apparent correlation between the planting methods and growth, but different results were observed among the same planting methods depending on nutrient solution used. Similarly, productivity followed a similar trend, with significantly higher harvest in the culture solution treatment during the initial harvest period of 6-8 weeks after sowing, but the harvest gap among treatments were diminished in the after period. The cumulative harvest was significantly higher in the culture solution treatment due to the initial difference in harvest quantity. Plant growth and fruit productivity exhibited a similar trend, showing a linear relationship. There was no correlation among the planting methods, but direct seedling with the culture solution showed the highest initial growth and harvests due to stable nutrient and moisture supply in the initial root zone. Therefore, it is believed that direct seeding method on the culture solution medium would be most advantageous for plant growth and productivity. Additionally, it is expected to contribute to cost effectiveness from an economic perspective through simplification of the cultivation process, labor costs and production cost reduction

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.349-354
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• 2013

This study examined a technique for cooling root zone aimed at lowering substrate temperature for sweet pepper (Capsicum annum L. 'Orange glory') cultivation in coir substrate hydroponics during hot season, from the $16^{th}$ of July to $15^{th}$ of October in 2012. The root zone cooling technique was applied by using an air duct (${\varnothing}12$ cm, hole size 0.1 mm) to blow cool air between two slabs during night (5p.m. to 3a.m.). Between the $23^{rd}$ of July and $31^{st}$ of August (hot temperature period), average daily substrate temperature was $24.7^{\circ}C$ under the root zone cooling, whereas it was $28.2^{\circ}C$ under condition of no cooling (control). In sunny day (600~700 W $m^{-2}{\cdot}s^{-1}$), average substrate temperatures during the day (6a.m. to 8p.m.) and night (8p.m. to 6a.m.) were lower about $1.7^{\circ}C$ and $3.3^{\circ}C$, respectively, under the cooling treatment, compared to that of control. The degree of temperature reduction in the substrate was averagely $0.5^{\circ}C$ per hour under the cooling treatment during 6p.m. to 8p.m.; however, there was no decrease in the temperature under the control. The temperature difference between the cooling and control treatments was $1.3^{\circ}C$ and $0.6^{\circ}C$ in the upper and lower part of the slab, respectively. During the hot temperature period, about 32.5% reduction in the substrate temperature was observed under the cooling treatment, compared to the control. Photosynthesis, transpiration rate, and leaf water potential of plants grown under the cooling treatment were significantly higher than those under the control. The first flowering date in the cooling was faster about 4 days than in the control. Also, the number of fruits was significantly higher than that in the control. No differences in plant height, stem thickness, number of internode, and leaf width were found between the plants grown under the cooling and control, except for the leaf length with a shorter length under the cooling treatment. However, root zone cooling influenced negligibly on eliminating delay in fruiting caused by excessively higher air temperature (> $28^{\circ}C$), although the substrate temperature was reduced by $3^{\circ}C$ to $5.6^{\circ}C$. These results suggest that the technique of lowering substrate temperature by using air-duct blow needs to be incorporated into the lowering growing temperature system for growth and fruit set of health paprika.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.157-167
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• 2003

In this paper, to reduce the resonant length of patch, microstrip patch antenna of linear polarization which is suppressed at two radiation edges is designed and fabricated at the frequency of 1.575 GHz. The result is like that the resonant length of patch is 45 mm and the length reduction effect is 43.8 % when it is compared with that(80 mm) of plane type. The gain is 4.4 dBd and -3 dB beamwidths are 112$^{\circ}$ and 66$^{\circ}$ in the E-plane and H-plane, respectively. Also, to reduce the size of patch, microstrip patch antennas those are suppressed at four radiating comers are designed and fabricated at the same frequency in the linear and circular polarization, respectively. For linear polarization, at the 1.2 of width/length(W/L) ratio, the patch area is 53 mm $\times$ 63.6 mm and the size reduction effect is 56.1 % when compared with that(80 mm $\times$ 96 mm) of plane type. The gain is 4.3 dBd and the -3 dB beamwidths are 120$^{\circ}$ and 78$^{\circ}$ in the E-plane and H-plane, respectively. For circular polarization, the patch size(54.2 mm $\times$ 61.5 mm) is reduced by 47.2 % than that(76 mm $\times$ 83 mm) of plane type. -3 dB beamwidth of horizontal polarization in the z-x plane and vortical polarization in the y-z plane are 108$^{\circ}$ and 93$^{\circ}$, respectively and this means the increasement in both planes by 52$^{\circ}$ and 27$^{\circ}$ than those of plane type. The maximum gain is 2.5 dBd in the horizontal polarization in the z-x plane. Axial ratio is 1.5 dB at 1.575 GHz and the 2 dB axial ratio bandwidth(ARBW) is 20 MHz(1.3 %).

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.47-55
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• 2018

Talc, hydrous magnesium phyllosilicate, is one of the most popular industrial minerals due to their chemical stability and adsorptivity. While micro-sized talc has long been used as a filler and coating, nano-sized talc recently is attracting attention as additives for improving the stability of nanocomposites. In this study, we produced the nano-sized talc powder by mechanical method using high energy ball mill and investigated the changes in particle size and crystallinity with increasing milling time up to 720 minutes. X-ray diffraction results show that the peak width of talc gradually as the milling proceeded, and after 720 minutes of pulverization, the talc showed an amorphous-like X-ray diffraction pattern. Lase diffraction particle size analysis presents that particle size of talc which was ${\sim}12{\mu}m$ decreased to ${\sim}0.45{\mu}m$ as the milling progressed, but no significant reduction of particle size was observed even after grinding for 120 minutes or more. BET specific surface area, however, steadily increases up to the milling time of 720 minutes, indicating that the particle size and morphology change steadily as the milling progressed. Scanning electron microscope and transmission electron microscope images shows that layered particles of about 100 to 300 nm was aggregated as micro-sized particles after pulverization for 720 minutes. As the grinding time increases, the particle size and morphology of talc continuously change, but the nano-sized talc particles form micro sized agglomerates. These results suggest that there is a critical size along the a, b axes in which the size of plates is reduced even though the grinding proceeds, and the reduction of plate thickness along the c axis leads the increase in specific surface area with further grinding. This study could enhance the understanding of the mechanism of the formation of nano-sized talc by mechanical grinding.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.181-187
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• 2002

The overall objective of this study was to improve tomato fruit quality, while maximizing yield. The variety of 'Momotaro' was grown in the basic nutrient solution of 1.6 dS.m$^{[-10]}$ which was supplemented by three levels of seawater with EC 1.0, 2.0 or 3.0 dS.m$^{[-10]}$ . Tomato plants were cultivated in cool seasons. Plant growth characteristics were compared between treatments, and fruits were classified to analyse fruit quality characteristics according to ripening stages： MG, Br, Br＋3, Br＋5, Br＋7 and Br＋10. Adding seawater generally did not affect the shoot growth parameters such as plant height, leaf length, leaf width, internode length and chlorophyll content. Adding seawater negatively affected yield parameters such as the height and weight of fruit, marketable fruit weight per plant and marketable fruit yield. Therefore, the more yield reduction was obtained with the increasing level of seawater treatment. Fruit quality was improved by seawater treatment. The degree of the effect for $^{\circ}$Bx degree and sugars were the highest with the EC of seawater 2.0~3.0 dS.m$^{[-10]}$ , and at the Br＋5~Br＋7 of ripening stages. The relative abundance of tomato flavor, volatile components, was not generally affected by the seawater treatment with an exception of 6-methyl-5-hepten-2-one. The relative abundance of most volatile components increased as ripening progressed. The increment began at the Br stage and showed the highest increment at the Br＋5~Br＋7 stages. The results from these experiments suggest that seawater treatment of EC 3.6 dS.m$^{[-10]}$ for hydroponics is good for improving tomato quality. Fruit quality is the best at the Br＋5~Br＋7 ripening stages. It is considered that these results may be applied far use in hydroponic culture to improve fruit quality with minimum yield reduction.