• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.6
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• pp.140-145
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• 2017

A channel is very sever in an underwater acoustic communication. Therefore, a modulation method with high spectrum efficiency is needed in an underwater acoustic communication. PSK(phase shift keying) for transmitting 1 bit or 2 bits is robust to noise, but sensitive to noise about more than 3 bits. CPFSK error performance for transmitting 1 bit or 2 bits is similar to that of PSK and CPFSK decreases high frequency components in modulation signal. In the paper, I analyze the performance of trellis coded 4-CPFSK modulation.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.1
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• pp.84-90
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• 2007

This paper was studied on the electrochemical corrosion characteristics of weld zone for refrigerating and heating systems pipe. Austenitic stainless steel is widely applied to various fields of industry, because it is good to corrosion resistance and mechanical properties. But STS 304 is reliable to sensitization by heat cycle on welding. Therefore, in this study, electrochemical polarization test of STS 304 steel pipe manufactured by arc welding in tap water was carried out. And then polarization resistance behavior, uniform and local corrosion behaviors of base metal(BM), weld metal(WM) and heat affected zone(HAZ) for STS 304 pipe were investigated. The corrosion current density of STS 304 steel pipe is high in order of BM(153nA/cm2) < WM(614nA/cm2) < HAZ ($1.675{\mu}A/cm2$). The pitting potential of HAZ(238mV/SCE) for STS 304 is lower than BM(1206mV/SCE) and WM(369mV/SCE). Therefore, the local corrosion like pitting corrosion, galvanic corrosion and crevice corrosion of HAZ for STS 304 is more sensitive than BM and WM.

• Journal of the Korean Ceramic Society
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• v.12 no.1
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• pp.16-22
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• 1975

The network structure of a glass is known to be cracked by a chemical reaction, diffusion, and ion exchange of alkali ion, formed at the crack tip of the glass surface, when water is present on the glass surface. Since the durability of glass is reduced, due to the fatigue phenomenon mentioned above, pollution problem of glass goods, especially bottle glass, is becoming acute gradually. A static fatigue phenomenon was studied thermodynamically in this paper, and a mechanism of static fatigue, a quality control, and a method of preventing pollution for the main local glass goods were also investigated. The PH of reacted solution and the quantity of extracted alkali were measured at different conditions such as temperature, reacting time, particle size of a crushed glass sample, and the nature of reacting solution. The enthalpy change was calculated from the Arrhenius equation. The results are given below; 1) The absolute value of enthalpy change for the bottle glass was found to be higher than the for the flat glass. 2) The fatigue phenomenon of a glass was more sensitive to the temperature than to the reacting time. 3) The durability of glass in acid solution is stronger than in alkaline solution. 4) The substance which cracks the network structure of glas is considered the hydroxyl ion.

• Wind and Structures
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• v.37 no.2
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• pp.95-104
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• 2023

The latest revision of AS/NZS 1170.2 incorporates some new research and knowledge on strong winds, climate change, and shape factors for new structures of interest such as solar panels. Unlike most other jurisdictions, Australia and New Zealand covers a vast area of land, a latitude range from 11° to 47°S climatic zones from tropical to cold temperate, and virtually every type of extreme wind event. The latter includes gales from synoptic-scale depressions, severe convectively-driven downdrafts from thunderstorms, tropical cyclones, downslope winds, and tornadoes. All except tornadoes are now covered within AS/NZS 1170.2. The paper describes the main features of the 2021 edition with emphasis on the new content, including the changes in the regional boundaries, regional wind speeds, terrain-height, topographic and direction multipliers. A new 'climate change multiplier' has been included, and the gust and turbulence profiles for over-water winds have been revised. Amongst the changes to the provisions for shape factors, values are provided for ground-mounted solar panels, and new data are provided for curved roofs. New methods have been given for dynamic response factors for poles and masts, and advice given for acceleration calculations for high-rise buildings and other dynamically wind-sensitive structures.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.427-435
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• 2023

This study was conducted to evaluate the spraying performance according to the flight conditions of agricultural drones for the development of a variable control system. The analyzed flight conditions comprised six factors: spraying direction, flight speed, altitude, wind speed, wind direction, and rotor rotational speed. The ratio of the area sprayed on the water-sensitive paper was used as the coverage, and the distribution and amount of the coverage were evaluated. The coverage distribution based on the distance from the drone was used to evaluate a spray pattern, and the distribution was expressed as a Gaussian function approximation. In addition, the probability distribution based on coverage was expressed as the cumulative probability via Gamma function approximation to analyze the spraying efficiency in the target area. The results showed that the averaged coverage decreased significantly as the flight speed and wind speed increased, and the wind direction changed the spray pattern without a coverage decrease. This study contributes to the development of a control technique for the precision control system of agricultural drones.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.140-142
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• 2023

Federated learning (FL) is a new paradigm in machine learning (ML) that enables multiple devices to collaboratively train a shared ML model without sharing their local data. FL is well-suited for applications where data is sensitive or difficult to transmit in large volumes, or where collaborative learning is required. The Internet of Underwater Things (IoUT) is a network of underwater devices that collect and exchange data. This data can be used for a variety of applications, such as monitoring water quality, detecting marine life, and tracking underwater vehicles. However, the harsh underwater environment makes it difficult to collect and transmit data in large volumes. FL can address these challenges by enabling devices to train a shared ML model without having to transmit their data to a central server. This can help to protect the privacy of the data and improve the efficiency of training. In this view, this paper provides a brief overview of Fed-IoUT, highlighting its various applications, challenges, and opportunities.

• Tunnel and Underground Space
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• v.8 no.3
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• pp.184-193
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• 1998

In order to dispose radioactive wastes safely, it is needed to understand the mechanical, thermal, fluid behavior of rockmass and physico-chemical interactions between rockmass and water. Also, the knowledge about mechanical and hydraulic properties of rocks is required to predict and to model many conditions of geological structure, underground in-situ stress, folding, hot water interaction, intrusion of magma, plate tectonics etc. This study is based on researches about rock mechanics issues associated with a waste disposal in deep rockmass. This paper includes the mechanical and hydraulic behavior of rocks in varying temperature conditions, thermo-hydro-mechanical coupling analysis in rock mass and deformation behavior of discontinuous rocks. The mechanical properties were measured with Interaken rock mechanics testing systems and hydraulic properties were measured with transient pulse permeability measuring systems. In all results, rock properties were sensitive to temperature variation.

• Environmental and Resource Economics Review
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• v.15 no.1
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• pp.1-26
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• 2006

This paper explores the relatilonship between state level environmental regulations and stocking and location decisions in the U.S livestock and poultry industry (beef, chicken, dairy and hogs), Rather than conduct this analysis on a species by species basis, the overall size of the livestock industry(expressed in animal units) and the size of Industry found on large, medium and small operations by state (48) and over time (29 years), which is panel data analysis, Generally, regulations seem to be induced by the structural change of industry; when industry creates externalities, regulators try to address them with policy tools to internalize them, Written regulatory stringency may not effect behavioral change; rather the state's willingness to enforce regulations seems to have a measurable influence. However, in the presence of rapid structural change, industry location is affected by written regulatory stringency. Policy enforcement activity was shown to influence inventory decisions in general and larger operations were found to be more sensitive to willingness to enforce than smaller operations.

• Membrane Journal
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• v.25 no.2
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• pp.85-98
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• 2015

A global trend of replacing metal or glass containers with polymer-based packaging materials has been prevalent in the food packaging industry due to their ease in processibility, excellent transparency, and good cost efficiency. Barrier polymers tend to show low permeabilities for atmospheric gases such as oxygen, carbon dioxide, and water vapor, which allow them to be utilized in the food and beverage packaging industry. With the current global trend, expansion of polymeric packaging materials to new markets such as oxygen sensitive juices, flavored water, and energy drinks requires improved $CO_2$ and $O_2$ barrier properties. The improvement of the existing polymer-based barrier platform will enable a rapid market impact. In this paper, the current barrier technologies such as (1) antiplasticization-induced barrier materials, (2) synergistic effect of antiplasticization and crystallization, (3) new barrier polymers, (4) nanocomposite materials, and (5) polymer blending are introduced with their characterization techniques for the development of advanced packaging materials.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.93-99
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• 2020

A colorimetric paper sensor was used to detect volatile nitrogen-containing compounds emitted from spoiled salmon filets to determine their freshness. The sensing mechanism was based on acid-base reactions between acidic pH-indicating dyes and basic volatile ammonia and amines. A sensing layer was simply fabricated by drop-casting a dye solution of bromocresol green (BCG) on a polyvinylidene fluoride substrate, and its color-change response was enhanced by optimizing the amounts of additive chemicals, such as polyethylene glycol, p-toluene sulfonic acid, and graphene oxide in the dye solution. To avoid the adverse effects of water vapor, both faces of the sensing layer were enclosed by using a polyethylene terephthalate film and a gas-permeable microporous polytetrafluoroethylene sheet, respectively. When exposed to basic gas analytes, the paper-like sensor distinctly exhibited a color change from initially yellow, then to green, and finally to blue due to the deprotonation of BCG via the Brønsted acid-base reaction. The use of ammonia analyte as a test gas confirmed that the sensing performance of the optimized sensor was reversible and excellent (detection time of < 15 min, sensitive naked-eye detection at 0.25 ppm, good selectivity to common volatile organic gases, and good stability against thermal stress). Finally, the coloration intensity of the sensor was quantified as a function of the storage time of the salmon filet at 28℃ to evaluate its usefulness in monitoring of the food freshness with the measurement of the total viable count (TVC) of microorganisms in the food. The TVC value increased from 3.2 × 10⁵ to 3.1 × 10⁹ cfu/g in 28 h and then became stable, whereas the sensor response abruptly changed in the first 8 h and slightly increased thereafter. This result suggests that the colorimetric response could be used as an indicator for evaluating the degree of decay of salmon induced by microorganisms.