• Journal of Food Hygiene and Safety
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• v.34 no.5
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• pp.473-479
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• 2019

The purpose of this study was to investigate the storage stability of liquid stick packs containing concentrated and steam-dried ginseng berry. Storage stability of liquid stick packs was determined during storage at 10, 25 and $35^{\circ}C$ for 4 months. The pH was decreased from 4.81 to 3.81 after 4 months at $35^{\circ}C$ while the acidity and solubility were not changed during storage of 4 months. The DPPH radical scavenging activity was decreased during storage at $35^{\circ}C$ after 4 months. The Hunter L and yellowness (b) values decreased while the redness (a) was not changed during storage after 2 or 3 months. The total amount of six ginsenosides including Rg1, Rb1, F2, Rg3(S), Rg3(R), and Rg5 was not changed after storage of 4 months at 10 and $25^{\circ}C$. Neither bacteria nor coliforms were not detected during storage of 4 months. Considering quality parameters, significant changes were observed in color parameters L and b, while all others remained unchanged during 4 months stored at 10 and $25^{\circ}C$.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.67-92
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• 2009

A tugboat (tug) is a boat that maneuvers vessels by pushing or towing them. Tugs move vessels that should not move themselves alone, such as ships in a crowded harbor or a narrow canal, or those that cannot move themselves, such as barges, disabled ships, or oil platforms. Tugboats are powerful for their size and strongly built, some are ocean-going. Historically tugboats were the first seagoing vessels to receive steam propulsion, freedom from the restraint of the wind, and capability of going in any direction. As such, they were employed in harbors to assist ships in docking and departure. Towage is in essence a service by one vessel to another vessel for a fixed remuneration. The most common reason for requiring this service is the lack of its own motive power. Conventionally, towage is defined as "the employment of one vessel to expedite the voyage of another, when nothing more is required than the accelerating of her progress". Apart from accelerating vessels, acquiring towage service is a common practice for towing barges, platform of drilling oil, floating ship yards, etc.

• Nuclear Engineering and Technology
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• v.16 no.3
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• pp.141-154
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• 1984

An analysis is presented of key phenomena and scenario which imply some general trends for beyond design-basis-accident in Kori-1 PWR dry containment. The study covers a wide range of severe accident sequences initiated by small break LOCA. The MARCH computer code, with KAERI modifications was used in this analysis. The major emphasis of the paper are two folds, 1) the phenomenologic understanding of severe accident and 2) a study of H2 combustion and debris/ water interactions in a specific small break LOCA for Kori-1 plant. The sensitivity studies for the specific plant data and thermal interaction modelings used in the SASA were performed. The results show that if hydrogen burning does occur at low concentration, the resulting peak pressure does not exceed the design value, while the lower concentration assumption results in repeated burning due to the continuing H$_2$ generation. For debris/water interaction, the particle size has no effect on the magnitude of peak pressure for the amount of water assumed to be in the reactor cavity. But, the occurrence of peak pressure is considerably delayed in case of using the dryout correlation. The peak containment pressure predicted from the hydrogen combustion and steam pressure spite during full core meltdown scenario does not present a severe threat to the containment integrity.

• Nuclear Engineering and Technology
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• v.45 no.4
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• pp.513-522
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• 2013

The ODSCC detected in the TSP position of Ulchin 3&4 SGs are typical ODSCC of Alloy 600MA tubes. The causative chemical environment is formed by concentration of impurities inside the occluded region formed by the tube surface, egg crate strips, and sludge deposit there. Most cracks are detected at or near the line contacts between the tube surface and the egg crate strips. The region of dense crack population, as defined as between $4^{th}$ and $9^{th}$ TSPs, and near the center of hot leg hemisphere plane, coincided well with the region of preferential sludge deposition as defined by thermal hydraulics calculation using SGAP computer code. The cracks developed homogeneously in a wide range of SGs, so that the number of cracks detected each outage increased very rapidly since the first detection in the $8^{th}$ refueling outage. The root cause assessment focused on investigation of the difference in microstructure and manufacturing residual stress in order to reveal the cause of different susceptibilities to ODSCC among identical six units. The manufacturing residual stress as measured by XRD on OD surface and by split tube method indicated that the high residual stress of Alloy 600MA tube played a critical role in developing ODSCC. The level of residual stress showed substantial variations among the six units depending on details of straightening and OD grinding processes. Youngwang 3&4 tubes are less susceptible to ODSCC than U3 and U4 tubes because semi-continuous coarse chromium carbides are formed along the grain boundary of Y3&4 tubes, while there are finer less continuous chromium carbides in U3 and U4. The different carbide morphology is caused by the difference in cooling rate after mill anneal. There is a possibility that high chromium content in the Y3&4 tubes, still within the allowable range of Alloy 600, has made some contribution to the improved resistance to ODSCC. It is anticipated that ODSCC in Y5&6 SGs will be retarded more considerably than U3 SGs since the manufacturing residual stress in Y5&6 tubes is substantially lower than in U3 tubes, while the microstructure is similar with each other.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.387-393
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• 2011

We analyzed the particle size distributions of three commercially available Devarda's alloy (DA) products, tested the nitrate recoveries of each particle size category, and examined the amounts of DA required for 100% recovery by varying $NO_3$-N concentration from 0.5 to 10 mg. We observed that use of DA coarser than 200 mesh resulted in poor analytical recovery (<80%). While the tested alloys were considered to be fine enough (>90% of the particles were less than 100 mesh), the recovery dramatically declined from 80% to 10% in a high concentration range (4 to 10 mg N). Satisfactory recovery was obtained by increasing the amount of finer DA (less than 300 or 450 mesh). However, there was no quantitative relationship between the amount of fine DA and nitrate recovered. Generally, the amount of nitrate reduced per unit DA decreased as the recovery efficiency declined. These results suggest that a sufficient amount of DA must be determined based on particle size distribution, and that treatment of at least two levels of DA and comparison of the subsequent change in nitrate recovery is required for soils containing high levels of nitrate. In addition, further studies are encouraged to account for the observed stoichiometric dis-equivalence of recovered nitrate N per unit mass of DA.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.647-655
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• 2021

The IMO (International Maritime Organization) is discussing the improvement of energy ef iciency of ships in order to reduce greenhouse gas emissions from ships. Currently, by applying an ORC power generation system using waste heat generated from ships, high energy conversion efficiency can be expected from ships. This technology uses an organic medium based on Freon or hydrocarbons as the working fluid, which evaporates at a lower temperature range than water. Through this, it is possible to generate steam (gas) and generate power at a low and low temperature relatively. In this study, the analysis of heat flow between the refrigerant and waste heat in the ORC power generation system, which is an organic Rankine cycle, is analyzed using 3D simulation techniques to determine the temperature change, velocity change, pressure change, and mass change of the fluid flowing of the WHRU (Waste Heat Recovery Unit) inside and the outside the structure. The purpose of this study is to analyze how the mass change affects the structure, and this study analyzed the heat transfer of the heat exchanger from the refrigerant and the exhaust gas of the ship's main engine in the ORC power generation system using this technique.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.2
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• pp.173-192
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• 2021

The purpose of this study is to analyze the previous research on geological fieldwork from 2000 to 2020, examine the tasks that have been focused on, and suggest directions and implications for future geological fieldwork research. The data was conducted for the thesis searched on ScienceON and RISS in relation to geological fieldwork and journals listed in the Korean Citation Index(KCI), and the study title was analyzed using the semantic network analysis. For analysis, the data that had been pre-processed was visualized as a network by semantic network analysis, and frequency and centrality were analyzed. The centrality analysis was based on degree centrality and eigenvector centrality, and all analyzes were performed by dividing the entire study period into four periods: 2000-2005, 2006-2010, 2011-2015, and 2016-2020. As a result, research on geological fieldwork focused more on the development of geological field courses, and in particular, jeju island was actively discussed as a learning site. Also, the study was conducted on students rather than teachers, and among them, high school students showed high frequency and centrality. In addition, it can be seen that studies on the educational effect of geological fieldwork were discussed, either in connection with programs such as STEAM, free-semester program, or indirect geological fieldwork methods such as web, flash panorama, and 3D. This study is meaningful in that it suggests the direction of future research by looking back on the research on geological fieldwork that has been done so far.

• Korean Journal of Organic Agriculture
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• v.28 no.4
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• pp.591-604
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• 2020

The objectives of this study were to find out the best condition of extracting methods of limonene from citron and to determine effects of limonene on immune modulation activity by measuring cytokine secretion using RAW 264.7 mouse macrophage cells. When distilled water was used as a solvent instead of organic solvents to extract limonene from citron, addition of refluxing process to simultaneous steam distillation extraction method was found to be much effective in extracting limonene. However, it required longer extraction time than using other organic solvents. Limonene extracts showed increased IL-β and IL-6 but decreased the TNF-α gene expression in limonene concentration dependant manner. However oral administration of limonene extracts to mice did not influence significantly compared to control in in vivo experiment. It might be due to that the mice were kept in well controlled and complete environment. Limonene, a natural material from citron has been approved to have a immune-modulation activity in the present study and have a potential as a feed additive that is environmentally friendly and no harmful. Further study with protected limonene, for example, for the protection of limonene from oxidation or bypass the ruminal degradation in order consequently to increase immune-modulation activity might be useful as a further research.

• 대한공업교육학회지
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• v.44 no.1
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• pp.162-189
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• 2019

The purpose of this study is to develop and apply a Design Thinking-based Maker education program utilizing Arduino for middle school students. The study progress was made in four stages of preparation, development, implementation and evaluation according to the PDIE model. In this study, experts were verified for validity and pre-applied to students to improve the maker education program developed based on literature review. Then, it was applied to middle school club classes to check the effects through analysis of quantitative and qualitative data. In addition, the development of the program was completed by supplementing the improvements found in the course. The results of this study are as follows. First, the topics of the maker education program that can be used in middle schools were selected in consideration of the analysis of the 2015 revised curriculum, methods to using the Arduino, and social interest. Second, the program developed based on the selected topic consists of 4 classes of maker basic learning and 16 classes of design thinking-based maker activities. Third, the developed maker education program had a significant effect in improving STEAM literacy of middle school students, but did not have any significant effect in the interest in technology and orientation towards an engineering career. Fourth, learners were interested in the activities of designing and freely making by themselves, and they positively evaluated the experience of realizing the physical computing with Arduino. In addition, they practiced the spirit of a maker, such as autonomously collecting data and sharing them with colleagues, etc. while acting as a maker.

• Journal of the Korean Wood Science and Technology
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• v.47 no.4
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• pp.519-532
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• 2019

The objectives of this study were to evaluate the effects of shelling ratio and resin content on the properties of bamboo oriented strand board (BOSB) from betung (Dendrocalamus asper) and to determine the correlation between the results of dynamic and static bending tests. Strands were steam-treated at $126^{\circ}C$ for 1 h under 0.14 MPa pressure and followed by washing with 1% NaOH solution. Three-layer BOSB with the core layer perpendicular to the surface was formed with shelling ratios (face:core ratio) of 30:70; 40:60; 50:50; 60:40 and binded with 7% and 8% of phenol formaldehyde (PF) resin with the addition of 1% of wax. The evaluation of physical and mechanical properties of BOSB was conducted in accordance with the JIS A 5908:2003 standard and the results were compared with CSA 0437.0 standard for commercial OSB (Grade O-1). Non-destructive testing was conducted using Metriguard Model 239A Stress Wave Timer which has a wave propagation time from 1 to $9,999{\mu}s$ and a resolution of $1{\mu}s$. BOSB with 8% resin content showed better physical and mechanical properties than those with 7% resin content. The increase of the face layer ratio improved the strength of BOSB in parallel direction to the grain. The results suggested that shelling ratio of 50:50 could be used as a simple way to reduce PF resin requirements from 8% to 7% and to meet the requirements of CSA 0437.0 standard. The results of non-destructive and destructive tests showed a strong correlation, suggesting that non-destructive test can be used to estimate the bending properties of BOSB.