• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.3
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• pp.201-209
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• 2021

There is a growing interest in rice cultivation on farms with irrigation facilities in desert climates. We investigated the growth characteristics and yields of two rice cultivars (FL478 and Asemi) irrigated at field capacities (FCs) of 80%, 100%, and 120% in a lysimeter with coarse sandy soils. The results showed that at the heading stage, the FC 100% treatment had the highest plant height and number of tillers between the two cultivars. At the harvest period, the culm and panicle lengths of both cultivars at FC 100% were similar to those of the control. In contrast, the number of panicles, grain number per panicle, and percentage of ripened grains were the highest in the control. Moreover, FL478 and Asemi had the highest grain yields of 1.40 and 2.20 kg·pot^-1 in the control, respectively. For both cultivars, the grain yields of the FC 100% and FC 120% treatments were approximately 70% of the control. In comparison, FL478 and Asemi had the highest water productivity of 0.45 and 0.63 kg·m^3-1 for the FC 80% treatment, followed by the FC 100% treatment (0.42 and 0.59 kg·m^3-1, respectively), which was nearly 14.3% and 20.3% higher than that of the control. Therefore, we found that irrigation at FC 100% is anticipated to be effective in managing surface drip irrigation for rice cultivation in desert climates in arid environments, while maintaining rice yields.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.781-788
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• 2021

Due to the high sensitivity to radiation, excessive exposure needs to be prevented by accurately measuring the dose irradiated to the skin during radiation therapy. Although clinical trials use dosimeters such as film, OSLD, TLD, glass dosimeter, etc. to measure skin dose, these dosimeters have difficulty in accurate dosimetry on skin curves. In this study, to solve these problems, we developed a skin dosimeter that can be attached according to human flexion and evaluated its response characteristics. For the manufacture of the dosimeter, lead oxide (PbO) with high atomic number (Z_Pb: 82, Z_O: 8) and density (9.53 g/cm³) and silicon binders that can bend according to human flexion were used. In the case of a dosimeter made of PbO material, the performance degradation has been prevented by using parylene and others due to the presence of degradation due to oxidation, but the previously used parylene is affected by bending, so a new form of passive layer was produced and applied to the skin dosimeter. The characteristic evaluation of the skin dosimeter was evaluated by analyzing SEM, reproducibility, and linearity. Through SEM analysis, bending was evaluated, reproducibility and linearity at 6 MeV energy were evaluated, and applicability was assessed with a skin dosimeter. As a result of observing the dosimeter surface through SEM analysis, the parylene passive layer PbO dosimeter with the positive layer raised to the parylene produced cracks on the surface when bent. On the other hand, no crack was observed in the silicon passive layer PbO dosimeter, which was raised to silicon passive layer. In the reproducibility measurement results, the RSD of the silicon passive layer PbO dosimeter was 1.47% which satisfied the evaluation criteria RSD 1.5% and the linearity evaluation results showed the R² value of 0.9990, which satisfied the evaluation criteria R² 9990. The silicon passive layer PbO dosimeter was evaluated to be applicable to skin dosimeters by demonstrating high signal stability, precision, and accuracy in reproducibility and linearity, without cracking due to bending.

• Korean Journal of Environment and Ecology
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• v.32 no.6
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• pp.603-617
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• 2018

This study surveyed the diversity and community characteristics of benthic macroinvertebrates and freshwater fish, which are the main animal classifications in a hydro ecosystem, from May to September 2017 in the western plains of the Demilitarized Zone (DMZ). The results showed a total of 125 species of benthic macroinvertebrates belonging to 66 families, 19 orders, and four phyla in the streams and wetlands. Among benthic macroinvertebrates, Coleoptera (27 spp.: 21.60%) was the largest group in terms of species richness followed by Odonata (26 spp.: 20.80%), non-Insecta (22 spp.: 17.60%), and Hemiptera (11 spp.: 8.80%) occupying in the lentic area. Of the feeding function groups (FFGs), predators (51 spp.: 56.67%) showed a relatively larger presence, indicating the dominance of hygrophilous invertebrates that usually inhabit the freshwater wetlands or ponds. Of the habitat oriented groups (HOGs), climbers (33 spp.: 24.44%) and burrowers (17 spp.: 12.59%) were the dominant groups. This observation is typical in a slow flowing habitat and can lead to the disturbance of the ecosystem due to cannibalism among predators. Cannibalism can be caused by stress induced by various population and environmental factors. For the ecosystem services benchmark (ESB) value, site 13 appeared to be the highest with 82 marks while other sites showed relatively lower rates and indices (III water quality class with ${\alpha}$-mesosaprobic). The analysis result of stability factors showed that almost all sites were evaluated to be the I characteristic group with high resilience and resistance or the III characteristic group that was sensitive to environmental disturbance and formed uneven and unstable communities. Of the freshwater fishes, 46 species (3,405 individuals) belonging to 39 families and 18 orders were identified in all the investigated sites. Among them, Cyprinidae (30 spp.: 65.2%) was the largest group, and Zacco koreanus was identified as the dominant species (728 individuals, 21.4%). The survey of freshwater fish communities found both stable communities (sites 7 and 13) with low dominant index (0.39) and high diversity index (2.29) and unstable communities (sites 2, 3, 8, and 10) in opposite tendency. This survey found five Korean endemic species, 17 species belonging to the export controlled species, two endangered species level II (Lethocerus deyrollei and Cybister chinensis), and rare species (Dytiscus marginalis czerskii) among benthic macroinvertebrates. The survey also found an invasive species, Ampullarius insularus, which was distributed throughout the whole area and thus can continuously disturb the ecosystem in the western plain area in the DMZ. Of freshwater fish, one natural monument (Hemibarbus mylodon) and three endangered species level II (Acheilognathus signifer, Gobiobotia macrocephalus, and G. brevibarba) were observed. The survey also found four introduced species (Pomacea canaliculate, Carassius cuvieri, Lepomis macrochirus, Micropterus salmoides) in the western DMZ area, indicating the need for the protection and conservation measures.

• Journal of Food Hygiene and Safety
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• v.34 no.4
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• pp.354-360
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• 2019

In order to extend the shelf life of Wasabi paste, the effects of citric acid were confirmed at $35^{\circ}C$ for 28 days. Citric acid-treated groups contained citric acid in amounts of 0.05, 0.10, 0.17, 0.30, and 0.40%, respectively. Quality characteristics of Wasabi pastes were determined in pH, titratable acidity, soluble solid content, color values, microbial analysis (aerobic bacteria, yeast), gas production, and content of allyl isothiocyanate. The pH and titratable acidities of Wasabi pastes added with citric acid were indicated as 4.03-5.19 and 4.23-4.82%, respectively. Soluble solid content was significantly different according to concentrations of citric acid. L values showed the highest at $50.05{\pm}0.46$. a and b values were increased during the storage period. Total aerobic bacteria and yeast counts of Wasabi pastes were decreased in a dose-dependent manner. Gas production from Wasabi pastes showed at 19.55-19.80 mL/tube after 28 days of storage. The addition of citric acid (0.3% or more) to the Wasabi paste resulted in increased storage stability.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.212-228
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• 2013

Stone cultural heritages are repaired by the use of metal stiffeners. The problem is that this type of repair has been based on the experience of workers without specific guidelines and has caused various problems. This is to suggest the structural reinforcement and behavioral characteristics of metal rods to minimize the secondary damage of materials and have the specimens tested and verified to establish the guidelines on how to insert metal stiffeners. When only epoxy resin is applied to the cut surface, only 70% of the properties of the parent material are regenerated and it is required to structurally reinforce the metal stiffener for the remaining 30%. The metal rod is under the structural behavior after the brittle failure of stone material and the structural behavior does not occur when the metal stiffener is below 0.251%. When it accounts for over 0.5%, it achieves structural reinforcement, but causes secondary damage of parent materials. The appropriate ratio of metal stiffener for the stone material with the strength of $1,500kgf/cm^2$, therefore, should be between 0.283% and 0.377% of the cross section of attached surface to achieve reversible fracture and ductility behavior. In addition, it is more effective to position the stiffeners at close intervals to achieve the peak stress of metal rod against bending load and inserting the stiffener into the upper secions is not structurally supportive, but would rather cause damage of the parent material. Thus, most stiffeners should be inserted into the lower part and some into the central part to work as a stable tensile material under the load stress. The dispersion effect of metal rods was influenced by the area of reinforcing rods and unrelated to their diameter. However, it ensures stability under the load stress to increase the number of stiffeners considering the cross section adhered when working on large-scale structures. The development length is engineered based upon the diameter of stiffener using the following formula: $l_d=\frac{a_tf_y}{u{\Sigma}_0}$. Also, helically-threaded reinforcing rods should be used to perform the behaviors as a structural material.

• The Southeast Asian review
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• v.27 no.2
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• pp.245-271
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• 2017

The purpose of this study is to examine and assess the major characteristics and changes of politics, economy, and diplomacy in Thailand in 2016. Specifically, it reviewed the New Constitution that was passed in 2016, the confrontation between different political forces and the trend of military regime around the New Constitution, and the political instability caused by the accession of the new king to the throne. This study also set out to figure out changes to the economy and foreign relations of the country, including its relations with South Korea, under the military regime and make predictions for the impact and future prospects of King Bhumibol Adulyadej's death on the politics and economy of the country. In 2016, the politics of Thailand took a step further toward the transfer of power to civil government and established a foundation for an authoritarian system. The draft of the New Constitution, which does not seem to be democratic, was approved by a referendum and enabled the military authorities to continue their political interventions, even after the general election. The New Constitution, in particular, reduces the power of political parties itself in addition to simply keeping the Thaksin's party in check; thus, anticipating ongoing conflicts between the military authorities and political parties. In this situation, the absence of King Bhumibol Adulyadej, who used to play a decisive role in promoting the political stability of the country, and the accession of the new king to the throne raise concerns about the acceleration of political instability, which has continued after the coup and influenced the diplomatic relations of the country. Today, Thailand is distancing itself from Western nations that do not recognize the current military regime including the U.S.A. and EU member states and instead maintains a rapidly friendly and close relation with China. In 2016, the economy of Thailand made a gradual recovery rather than high growth. The death of King Bhumibol Adulyadej has exerted limited direct economic impacts only on individual consumption and tourism and is not likely to cause a recession. An economic crisis will, however, be unavoidable if the political confrontations escalate before the general election to transfer power to the civil government.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.52-69
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• 2021

The transcriptions of Buddhist sutra in the Goryeo Dynasty are more elaborate and splendid than those of any other period and occupy a very important position in Korean bibliography. Among them, the transcriptions made on indigo paper show decorative features that represent the dignity and quality that nobles would have preferred. Particularly, during the Goryeo Dynasty, a large number of transcriptions were made on indigo paper, often in hand-scrolled and folded forms. If flexibility was not guaranteed, the hand-scrolled form caused inconvenience and damage when handling the transcription because of the structural limitations of the material that is rolled up and opened. It was possible to overcome these shortcomings by changing from the hand-scrolled to the folded form to obtain convenience and structural stability. The folded form of the transcription utilizes the same principle as the folding screen, so it is a structure that can be folded and unfolded, and it is made by connecting parts at regularly spaced intervals. No matter how small the transcription is, if it is made of thin paper, it is difficult to handle it and to maintain its shape and structure. For this reason, the folded transcription was usually made of thick paper to support the structure, and the cover was made thicker than the inner part to protect the contents. In other words, the forded form was generally manufactured to suit the characteristics of maintaining strength by making the paper thick. Because a large amount of indigo paper was needed to make this type of transcription, it is assumed that there were craftsmen who were in charge only of dark dyeing the papers. Usually, paper dyeing requires much more dye than silk dyeing, and dyeing dozens of times would be required to obtain the deep indigo color of the base of the transcription of Buddhist sutra in the Goryeo Dynasty. Unfortunately, there is no record of the Goryeo Dynasty's indigo blue paper manufacturing technique, and the craftsmen who made indigo paper no longer remain, so no one knows the exact method of making indigo paper. Recently, Hanji artisans, natural dyers, and conservators attempted to restore the Goryeo Dynasty's indigo paper, but the texture and deep colors found in the relics could not be reproduced. This study introduces the process of restoring indigo paper in the Goryeo Dynasty through collaboration between dyeing artisans, Hanji artisans, and conservators for conservation of the transcription of Buddhist sutra in the late Goryeo dynasty, yielding a suggested method of making indigo paper.

• Journal of Nutrition and Health
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• v.54 no.2
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• pp.179-198
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• 2021

Purpose: This study examined general characteristics, health status, accessibility to medical services, health-related quality of life, dietary behavior, and energy and nutrient intakes of the elderly at different levels of food security utilizing data from the 7th Korea National Health and Nutrition Examination Survey (2016-2018). Methods: The elderly subjects (1,721 males and 2,271 females) were divided into 3 groups (secure, mildly insecure, moderately/severely insecure) according to their food security levels. Health and nutrient status was determined using energy intake, nutrient density, the prevalence of insufficient nutrient intake, dietary behavior, and health status. Results: The elderly with food insecurities had a lower self-evaluated health status and a higher prevalence of physician-diagnosed chronic diseases such as arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis for males, and hypertension, stroke, arthritis, and osteoarthritis for females. The associated financial burden was the major reason for not accessing medical services in the food insecure group. Furthermore, the food insecure group had a higher risk of impaired health-related quality of life compared to the secure group. The proportion of subjects with an energy intake below the estimated energy requirement was higher in the food insecure group and a significantly higher prevalence of insufficient intake was observed for all the nutrients (proteins, vitamin A, vitamin B₁, vitamin B₂, niacin, vitamin C, calcium, and iron) assessed in this study compared to the food secure group. Conclusion: This study suggests that food insecurity poses a challenge to the health and nutritional status of the elderly population in Korea and needs proper management. It would be helpful to develop food and nutrition assistance programs to ensure the food stability of the elderly population and assure quality to address gaps in their nutrient intake.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.45-53
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• 2022

In order to improve the emission of diesel engines, natural gas-diesel dual fuel combustion compression ignition engines are in the spotlight. In particular, a reactivity controlled compression ignition (RCCI) combustion strategy is investigated comprehensively due to its possibility to improve both efficiency and emissions. With advanced diesel direct injection timing earlier than TDC, it achieves spontaneous reaction with overall lean mixture from a homogeneous mixture in the entire cylinder area, reducing nitrogen oxides (NOx) and particulate matter (PM) and improving braking heat efficiency at the same time. However, there is a disadvantage in that the amount of incomplete combustion increases in a low load region with a relatively small amount of fuel-air. To solve this, sensitive control according to the diesel injection timing and fuel ratio is required. In this study, experiments were conducted to improve efficiency and exhaust emissions of the natural gas-diesel dual fuel engine at low load, and evaluate combustion stability according to the diesel injection timing at the operation point for power generation. A 6 L-class commercial diesel engine was used for the experiment which was conducted under a 50% load range (~50 kW) at 1,800 rpm. Two injectors with different spray patterns were applied to the experiment, and the fraction of natural gas and diesel injection timing were selected as main parameters. Based on the experimental results, it was confirmed that the brake thermal efficiency increased by up to 1.3%p in the modified injector with the narrow-angle injection added. In addition, the spray pattern of the modified injector was suitable for premixed combustion, increasing operable range in consideration of combustion instability, torque reduction, and emissions level under Tier-V level (0.4 g/kWh for NOx).

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.594-605
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• 2022

CaO was prepared by calcining for oyster shells using a microwave kiln. It was analyzed to Ca(OH)₂ synthed on hydration reaction from prepared CaO. The synthesized Ca(OH)₂ was formulated as an external water paint. Oyster shells (325 mesh, 43 ㎛) were decarbonized for (a) 950 ℃/1 hr and (b) 1,150 ℃/1 hr to prepare CaO. In the calcination condition of (a), CaO was 56.7 wt%, and in the calcination condition of (b), CaO was 100 wt%. To compare CaO by calcination of oyster shells with that of limestone, limestone (25~30 mm) was decarbonized at 950 ℃/1 hr to prepare CaO, and as a result of the analysis(XRD), it was analyzed as CaO 100 wt%. CaO was prepared under the calcining conditions of oyster shells (b) 1,150 ℃/1 hr, and Ca(OH)₂ was synthesized through hydration. Hydration conditions of the prepared CaO were (a) CaO : H₂O(100 g : 200 g) and (b) CaO : H₂O(100 g : 400 g). As a result of the hydration reaction, it was confirmed as low reactivity. 100 wt% of Ca(OH)₂ was synthesized. In particular, Ca(OH)₂ synthesized under the hydration condition of (a) was analyzed in a plate shape. An external water paint was formulated with Ca(OH)₂ synthesized from oyster shells as the main component. When 15 items of the external water paint standard specification (KS M 6010) were analyzed, it was confirmed that all other criteria were satisfied except for freezing stability.