• Journal of the Korean Wood Science and Technology
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• 제47권6호
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• pp.732-750
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• 2019

Air drying was carried out on 15 Korean red pine logs to provide a prediction model of the moisture content (MC) change in the wood during drying. The final MC was 17.4% after 880 days since the beginning of air drying in the summer for 6 Korean red pine logs with 68.7% initial MC. The final MC was 16.0% after 760 days since the beginning of air drying in the winter for 9 Korean red pine logs with 35.8% initial MC. A regression model with R-squared of 0.925 was obtained as a result of multiple regression analyses with initial MC, top diameter, temperature, relative humidity, and wind speed as independent variable and and MC change during air drying as dependent variable. The initial MC and top diameter, which is the characteristic of Korean red pine, have greater effect on the MC decrease during air drying compared to meteorological factors such as the temperature, relative humidity, and wind speed. Two-dimensional mass transfer analysis was performed to predict the MC distribution of Korean red pine logs during air drying. Two prediction models with different air drying days and different meteorological factors for the determination of the diffusion coefficient and surface emission coefficient were presented. The error between the different two methods ranged from 0.1 to 0.8% and the difference from the measured value ranged from 2.2 to 3.6%. By measuring the internal MC during air drying of Korean pine logs with various initial MC and diameter, and calculating the moisture transfer coefficient in wood for each meteorological condition, the error of the prediction model can be reduced.

• Journal of Soil and Groundwater Environment
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• 제13권3호
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• pp.52-58
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• 2008

Mn-impregnated activated carbon (Mn-AC) prepared at different conditions was applied in the treatment of synthetic wastewater containing both organic and inorganic contaminants. Phenol and As(III) was used as the representative organic and inorganic contaminants, respectively. After evaluation of the physicochemical characteristic and stability of Mn-AC, oxidation of As(III) as well as adsorption of phenol by activated carbon(AC) and Mn-AC were investigated in a batch reactor. To investigate the stability of Mn-AC, dissolution of Mn from each Mn-AC was measured pH ranging from 2 to 4. Although Mn-AC was unstable at a strong acidic condition, the dissoluted Mn was below 3 ppm at pH 4. XRD analysis of Mn-AC indicated that the mineral type of the impregnated manganese was $Mn_2O_3$. From the simultaneous treatment of As(III) and phenol by AC and Mn-AC, As(III) oxidation by Mn-AC was greater than that by AC at lower pH, while the reverse order was observed at higher pH. After impregnation of Mn onto AC, 13% decrease of the surface area was observed, causing 8% reduction of phenol removal. Considering removal properties of As(III) and phenol, Mn-AC could be applied in the simultaneous treatment of wastewater contaminated with multi-contaminants.

• Applied Chemistry for Engineering
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• 제32권6호
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• pp.599-606
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• 2021

In this study, an experiment and a reaction characteristic study were conducted to enhance the reaction activity of V₂O₅/WO₃/TiO₂ at 300 ℃ or less by adding selenium to the support, in a selective catalytic reduction method using ammonia as a reducing agent to remove nitrogen oxides. Se-TiO₂ and TiO₂ were synthesized using the sol-gel method, and used as a support when preparing V₂O₅/WO₃/TiO₂ and V₂O₅/WO₃/Se-TiO₂ catalysts. The reaction activity of our catalyst was compared with that of a commercial catalyst. The denitration efficiency of the catalyst using TiO₂ prepared by the sol-gel method was lower than that of the catalyst prepared using commercial TiO₂, but was improved by the addition of selenium. Thus, the effect of selenium addition on the catalyst structure was analyzed using BET, XRD, Raman, H₂-TPR, and FT-IR measurements and the effect of the increase in specific surface area by selenium addition and the formation of monomer and complex vanadium species on reaction characteristics were confirmed.

• Food Engineering Progress
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• 제15권3호
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• pp.250-256
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• 2011

This study was performed to analyze the quality characteristics of Sulgidduk added with different ratio 0, 10 and 15% (w/w) of apple pomace dietary fiber powder (DFP). Increasing DFP from 0% to 15% was decreased in color L* value from 87.9 to 65.9, while a* and b* values were increased from -1.9 to 5.9 and from 5.0 to 20.5, respectively. Scanning Electron Microscopy (SEM; ${\times}500$) showed that air cell size in the Sulgidduk surface increased as the DEP increased. On the other hand, control without DFP had a compact structure without air cell. Enthalpy by DSC showed that control without DFP, 10 and 20% DEP Sulgidduk after 3 days of storage were 4.83, 3.80 and 3.18 J/g at $4^{\circ}C$ and those of $25^{\circ}C$ were 1.14, 0.60 and 0.60 J/g, respectively. DEP had more effective on retarded retrogradation of Sulgidduk at $4^{\circ}C$ than that at $25^{\circ}C$. Hardness of 15% DEP Sulgidduk was around 42% compared to that of control without DFP after 3 days of storage at $4^{\circ}C$. In hedonic test, 15% DEP Sulgidduk showed the highest overall quality score among samples after making and storage 3 days at $4^{\circ}C$.

• Journal of Energy Engineering
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• 제27권4호
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• pp.1-12
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• 2018

The code and standards related to fuel cells were analyzed to derive the SOFC(Solid Oxide Fuel Cell) stack safety performance evaluation items and evaluation methode. Safety performance evluation of the SOFC stack was tested by quoting derived test items. The stack used in the test is an anode-supported type 2 Cell stack (Active surface area : 220cm) manufactured by MICO Inc, and SOFC stack safety performance evaluation system used for the test is self-manufactured. We conducted a leakage test, current voltage characteristic test, rated output test, and power response characteristics test. In the safety performance evaluation test, the stack showed no gas leakage, the maximum output and rated output was recorded to 65.6 W(1.41 V, 46.5 A, $422mA/cm^2$), 62.3 W(1.57 V, 40 A, $363mA/cm^2$). In the power response characteristics test verified that the output is kept stable within two seconds. At the maximum load (40 A) and the minimum load (8 A), the output was recorded 62 W and 16W in $750^{\circ}C$. This study will contribute to the universalization and to provide much safe environment of operating the solid oxide fuel cell system.

• Korean Journal of Heritage: History & Science
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• 제52권3호
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• pp.160-171
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• 2019

The sword with a ring pommel, which was excavated from the first stone chamber of the ancient tombs of Jeongchon Village in Naju, is a sword with a pentagon undecorated ring pommel consisting of a mother sword and two child swords. The sword with an undecorated ring pommel of Jeongchon comprises a ring pommel, a hilt, a knife, and a knife end decoration. This sword was coated with lacquer. The ring pommel is an iron frame covered with silver plate; however the silver tarnished into a light purple due to silver chloride corrosion, and iron corrosion originated from the inside is visible on the surface. Silver chloride corrosion is produced when silver objects are exposed to water, dissolved salts, and dissolved chloride ions when in a buried state. It changes objects into powder, making it difficult to preserve original shapes. The other silver artifacts found in the Jeongchon ancient tombs show similar signs of corrosion. The results of X-ray irradiation and a CT analysis showed that the sword had a ring at the end of the handle, a T-shaped hilt, and was probably connected to the handle end of a knife. If the shape of the mother sword can be inferred from the child swords, the mother sword had a ring pommel, decorations of the handle, covered with silver plate, and a gold ring and a silver line wound around the handle. It is assumed that the ring pommel was connected to the knife by welding because no holes were observed. The end decoration of the knife was made by using an iron plate formed into a shape, half covered by silk, and the other half decorated with silver plate and a gold ring. The sword with an undecorated ring pommel excavated from the ancient tombs of Jeongchon Village comprises the metals of gold, silver, and iron, and includes features of Baekje, Silla, and Gaya, which highlights the influence of surrounding historic sites and various cultures.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제33권5호
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• pp.203-216
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• 2021

Analyzing various wave interactions with oscillating wave surge converters (OWSC) is essential because they must be operated efficiently under a wide range of wave conditions and designed to extract optimal wave energy. In the conceptual design and development stage of OWSC, numerical analysis can be a good alternative as a design tool. This study performed a numerical analysis on the behavioral characteristics of the inverted triangle flap against the incident waves using open source CFD to examine the essential behavioral attributes of OWSC. Specifically, the behavioral characteristics of the structure were studied by calculating the free water surface displacement and the flap rotation angle near the inverted triangular flap according to the change of the period under the regular wave conditions. By comparing and examining the numerical analysis results with the hydraulic model experiments, the validity of the analysis performed and the applicability in analyzing the wave-structure interactions related to OWSC was verified. The numerical analysis result confirmed that the hydrodynamic behavior characteristic due to the interactions of the wave and the inverted triangle flap was well reproduced.

• Journal of Conservation Science
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• 제37권3호
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• pp.232-244
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• 2021

This study examined the physical attributes and heat treatment characteristics of glass beads excavated from the Gimhae area, which is the location of Geumgwan Gaya. This enabled classification of surface characteristics of the beads based on the investigation of the color, size, and shape. The glass beads were classified into eight color systems, with purplish-blue beads as the representative color. Bead size was categorized into three types depending on the outer diameter and how it increased over time. Bead shapes were categorized as round, tubular, or doughnut-shaped based on the inner diameter and length, with round being the typical shape. According to the degree of heat treatment, there are three types of cross-section for glass beads that are manufactured by the drawing technique, most of which are the HT-III type. In addition, it is estimated that the heat treatment technology has more considerable effects than other methods. Through non-destructive analysis, the chemical composition was obtained and categorized as flux, stabilizer, and colorant. Analysis confirmed the presence of 63 and 9 pieces in the potash and soda glass groups, respectively. Overall findings from the study highlighted a correlation between the chemical composition and the external factors such as color, size, shape, and manufacturing technology of glass beads recovered from Geumgwan Gaya, revealing characteristics related to that time and region.

• Journal of Navigation and Port Research
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• 제45권1호
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• pp.26-32
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• 2021

In ocean field, the spread of the Fourth Industrial Revolution based on information and communication technology requires high precision and stable PNT&D (Position, Navigation, Timing and Data). As the IMO (International Maritime Organization) and IALA (The International Association of Marine Aids to Navigation and Lighthouse Authorities) are requiring backup systems due to mitigate vulnerabilities and the increase of dependency on GNSS (Global Navigation Satellite System), Korea is conducting a research & development of R-Mode. An DGPS (Differentiate Global Positioning System) reference station that uses MF, an existing maritime infrastructure, and AIS (Automatic Identification System) base stations that use 34 integrity station and VHF will be utilized in this study to avoid redundant investment. Because there are radio shadow areas that display low signal levels in the west sea, the establishment of new R-Mode reference and integrity station will be intended to resolve problems regrading the radio shadow area. Because the frequency has a characteristic in that radio wave transmits well along the ground (water surface) in low frequency band, simulation and measurement were conducted therefore this paper to propose candidate sites for R-Mode reference and integrity station resulted through p wave's propagation characteristics analysis. Using this paper, R-Mode reference and integrity station can be established at appropriate locations to resolve radio shadow areas in other regions.

• (The)Study of the Eastern Classic
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• 제70호
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• pp.157-183
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• 2018

Mokjae Lee Samhwan's "MaengHoEum" is the three poems of the Chinese quatrain of 5word 7poetry created according to the previous age. This poem is distinguished from the poem of the general "MaengHoHaeng" series because of it was created in the form of modern-style poetry of series, not a poetry of 5word or 7word or length phrase in a poem. The "MaengHoEum" of MokJae seems to have been built around 1801year when he was 73 years old. Therefore, his "MaengHoEum" can be called an allegory poetry or a society poetry and his poetry can be said that it was created under the criticism of the corrupt political power of the contemporary society, and the 'fierce tiger' which appeared in his poem refers to the factions of Noron Byek line which was the ruling power at that time. However, if you look at the "MaengHoEum" of MokJae, you will see a criticism of the real world, but the feeling is not intense or the description is not concrete. Although his poetry depicts the absurdity of the present reality, but he does not show positive criticism of reality or strong resistance. This characteristic, which can be seen in his poem "MaengHoEum", is the result of the study he pursued for the his life and is thought to be due to the weight of reality. The contradictions of the time of the Mokjae were never silent to him, but on the other hand he could not reveal his own struggle on the surface of the poem. Between his descendants, influenced by his actions, and the stinging gaze watching him, he had no choice but to end his feelings internally.