• Resources Recycling
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• v.31 no.4
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• pp.40-48
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• 2022

In waste lithium iron phosphate (LFP) batteries, the cathode material contains approximately 4% lithium. Recycling the constituent elements of batteries is important for resource circulation and for mitigating the environmental pollution. Li contained in the waste LFP cathode powder was selectively leached using persulfate-based oxidizing agents, such as sodium persulfate, potassium persulfate, and ammonium persulfate. Leaching efficiency and waste LFP powder properties were compared and analyzed. Pulp density was used as a variable during leaching, which was performed for 3 h under each condition. The leaching efficiency was calculated using the inductively coupled plasma (ICP) analysis of the leachate. All types of persulfate-based oxidizing agents used in this study showed a Li leaching efficiency over 92%. In particular, when leaching was performed using (NH₄)₂S₂O₈, the highest Li leaching percentage of 93.3% was observed, under the conditions of 50 g/L pulp density and an oxidizing agent concentration of 1.1 molar ratio.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.2
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• pp.171-182
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• 2022

The habitat degradation caused by large-scale reclamation leads to devastating impacts, such as fine sediment and mud shrimp Upogebia major settlement on Manila clam Ruditapes philippinarum aquaculture in the eastern Cheonsu Bay tidal flats, Republic of Korea. Despite these impacts, there is a lack of studies on the influence of fine sediments on tidal flats that constitute key mud shrimp habitats. This study provides information on the seawater-sediment environment and the influence of dissolved inorganic nitrogen (DIN) fluctuations depending on mud shrimp burrow hole density. Additionally, it discusses countermeasures for Manila clam habitat management. The results show that mean DIN effluxes in areas with a high-density of burrow holes were up to 4 times (0.12 mmol m^-2 d^-1) higher than those in sites of low-density (0.03 mmol m^-2 d^-1) within the Saho and Songhak-ri tidal flats. To manage interference within the competition zone of Songhak-ri tidal flat, it is important to utilize the settlements of spawning season in all three dimensions. Consequently, additional studies in other tidal flats are essential and research in zones where mud shrimps and juvenile clams coexist will help to determine the priorities in the efficient management of clam aquaculture.

• Journal of Adhesion and Interface
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• v.23 no.4
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• pp.122-129
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• 2022

In this study, the hydrophilicity of the metal fiber is improved by introducing an oxygen-containing functional group to the fiber surface after treatment of the metal fiber using the oxygen plasma treatment time as an experimental variable. For the surface modification of metal fibers, changes in surface properties before and after plasma treatment were observed using SEM and x-ray photoelectron spectroscopy (XPS). In order to observe the effect of the plasma treatment time on the surface of the metal fiber, the change in contact angle of the metal fiber with respect to a polar solvent and a non-polar solvent was measured. After calculating the change in surface free energy using the measured contact angle, the contact angle and the surface free energy for metal fibers before and after oxygen plasma treatment were compared, and the correlation with the adhesion work was also considered. The microdroplet specimens were prepared to investigate the effect of surface changes of these metal fibers on the improvement of shear strength at the interface when combined with other materials and the interfacial shear strength was measured, and the correlation with the adhesion work was also identified. Therefore, the oxygen plasma treatment of the metal fiber results in an increase in the physical surface area on the fiber surface and a change in contact angle and surface energy according to the introduction of the oxygen-containing functional group on the surface. This surface hydrophilization resulted in improving the interfacial shear strength with the polymer resin.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.620-629
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• 2022

By varying various experimental conditions such as heating rate, molar hourly space velocity (MHSV), and nitridation reaction temperature, vanadium oxynitride was prepared through temperature programmed reduction/nitridation reaction (TPRN) of vanadium pentoxide and ammonia, and characterization were performed. In order to investigate the physico-chemical properties of the prepared catalyst, N₂ adsorption-desorption analysis, X-ray diffraction analysis (XRD), hydrogen temperature programmed reduction (H₂-TPR), temperature programmed oxidation (TPO), ammonia temperature programmed desorption (NH₃-TPD), transmission electron microscopy (TEM) was performed. Transformation of V₂O₅ with 5 m² g^-1 low specific surface area by reduction at 340 ℃ to V₂O₃ showed a high specific surface area value of 115 m² g^-1 by micropore formation. As the nitridation temperature increased beyond that, the specific surface area continued to decrease due to sintering. The nitridation reaction variable that had the greatest influence on the specific surface area was the reaction temperature, and the x + y value of VN_xO_y of a single phase approached from 1.5 to 1.0 as the nitridation reaction temperature increased. At a high reaction temperature of 680 ℃, the cubic lattice constant a was VN. close to the value. At 680 ℃, the highest nitridation temperature among the experimental conditions, the ammonia conversion rate was 93%, and no deactivation was observed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.325-332
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• 2008

To characterize the initiation, propagation and termination of Cochlodinium polykrikoides blooms in the southeast coastal waters of Korea, 2007, we have analyzed the data set of phytoplankton composition, physical and chemical water properties, and meterological data. The development of C. polykrikoides bloom in 2007 can be summarized in three steps. The first stage from middle of July to end of August was characterized by an unusually persistent and strong southerly wind. C. polykrikoides blooms established already by the strong wind in the middle of south coastal waters were advected intermittently into the study area. Accordingly, highly variable cell densities of C. polykrikoides were observed. At the second stage a favorable growing conditions for C. polykrikoides was developed, which was directed by changes in wind direction from south to northeast and thus enhanced transportation of offshore waters into inshore (August 8 to 30). C. polykrikoides bloom occurred through typical mechanism and showed high cell density. The last stage was represented by disappearance of C. polykrikoides. Typoon 'Nari' carrying heavy rain brought an unfavorable habitat to C. polykrikoides. Low saline condition formed in coastal water due to typoon effects continuously drove the dominant species to diatoms and flagellates which were prevailing over C. polykrikoides in this circumstances(from the middle of September). These stepwise processes could be the causative mechanism of the extraordinarily persistent C. polykrikoides bloom observed in southeast coastal water of Korea, 2007.

• Composites Research
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• v.37 no.3
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• pp.219-225
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• 2024

It is essential to develop a light-weight, high-performance structure for the deployable reflector antenna, which is the payload of a reconnaissance satellite, considering launch and orbital operation performance. Among them, the composite main reflector is a key component that constitutes a deployable reflector antenna. In particular, the development of a high-performance main reflector is required to acquire high-quality satellite images after agile attitude control maneuvers during satellite missions. To develop main reflector, the initial design of the main reflector was confirmed considering the structural performance according to the laminate stacking design and material properties of the composite main reflector that constitutes the deployable reflector antenna. Based on the initial design, four types of composite main reflectors were manufactured with the variable for manufacturing process. As variables for manufacturing process, the curing process of the composite structure, the application of adhesive film between the carbon fiber composite sheet and the honeycomb core, and the venting path inside the sandwich composite were selected. After manufacture main reflector, weight measurement, non-destructive testing(NDT), surface error measurement, and modal test were performed on the four types of main reflectors produced. By selecting a manufacturing process that does not apply adhesive film and includes venting path, for a composite main reflector with light weight and structural performance, we developed and verified a main reflector that can be applied to the SAR(Synthetic Aperture Rader) satellite.

• Journal of Korean Academy of Nursing
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• v.20 no.3
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• pp.324-340
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• 1990

Support has always been considered an important nursing concept. However, there is no agreement among nurse researchers as to a conceptual definition of supportive nursing or meaningful supportive behaviors. Clarification of the concept, support in nursing, is necessary to promote communication among nurses on nursing behaviors that are effective in providing support and on understanding the relevant properties and charcteristics of the concept, supportive nursing care. The objectives of the study were : 1. to analyse the concept, support in nursing, in order to provide a definition of supportive nursing care, and 2. to operationalize the definition of supportive nursing care and use it as an experimental nursing intervention for patients with low back pain. The first part of the study used the concept analysis approach developed by Walker and Avant(1983) to define the concept of supportive nursing care. The properties of supportive nursing care, defined by this analysis, included perception of supportive need, reciprocal interaction(Transaction), listening, providing empathy and information related to health, and confirmation of the patient's verbal and non - verbal response. The second part, the experimental part of the study, was done using King's(1970) Interpersonal Theory for Nursing. The concept, supportive nursing care, as defined in the concept analysis was operationalized and used as the experimental intervention. The experiment tested the effectiveness of the independent variable, supportive nursing care on the dependent variables, depression, mood and patient satisfaction, in the patients with low back pain in army hospitals. The instruments used to measure the dependent variables were Zung's(1965) Self- Rating Depression Scale, Ryman and Colleagues'(1974) Mood Questionnaire and LaMonica and Colleagues'(1986) Patient Satisfaction Scale. The experimental design used for this study was a Solomon 4 group experimental design. This design has the strength of allowing for observation of the main effects of supportive nursing care and pretesting, and for observation of the interaction effects of pretesting and supportive nursing care. The design includes one experimental group and three control groups. The Subjects of this study were 150 young male patients with low back pain on Neuro - Surgical Wards in three general army hospitals. There were 35 in the experimental group, 39 in the pre - posttest control group, 36 in the treatment - posttest control group and 40 in the posttest only control group. Supportive nursing care, as operationalized by the researcher according to the concept analysis, was given to the patients in the experimental group and the treatment -posttest control group, individually for 30 minute sessions, every other day for 5 days. Data collection was done using a questionnaire. The data were collected in a pretest one week before the supportive nursing care sessions, a posttest immediately after the sessions and follow- up test one week later. Hypotheses testing was done using 2×2 factorial analysis of variance and Meta analysis(Stouffer's Z method). The results of this study are summarized as follows : 1. Hypothesis Ⅰ, “There will be a difference on depression level between the patients with low back pain who receive supportive nursing care and those who do not receive supportive nursing care”, was supported (F＝8.49, p＜.05). 2. Hypothesis Ⅱ, “There will be a difference on mood level between the patients with low back pain who receive supportive nursing care and those who to not receive supportive nursing care”, was supported (Z meta＝2.17, p＜.05). 3. Hypothesis Ⅲ, “There will be a difference on satisfaction level between the patients with low back pain who receive supportive nursing care and those who do not receive supportive nursing care”, was supported (F＝13.67, p＜.05). 4. ANOVA, done to examine the interaction effect of history and maturation, showed no significant difference on the dependent variables between the observations of the pretest scores of the experimental group, the pretest scores of the pre- posttest control group and the posttest score of the posttest only control group. 5. To test for continuing effect of supportive nursing care, paired t-test was done to compare the scores for the dependent variables at the posttest and at the one week later follow-up test. No significant difference on the scores for the dependent variables was found between the posttest scores and the follow-up test scores for the two groups that received supportive nursing care, the experimental group and the treatment-posttest control group. In conclusion, it was found that in the case of young soldiers with low back pain in army hospitals, their depression level was decreased, their mood state was changed positively and their satisfaction level was increased by receiving supportive nursing care. Further, the effectiveness of the supportive nursing care lasted for at least one week in this study. The significance of this study to nursing is in the analysis of the concept of supportive nursing care and the demonstration of the effectiveness of supportive nursing care as an intervention within the limits of the study.

• Journal of Korean Society of Forest Science
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• v.77 no.3
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• pp.294-302
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• 1988

The experiment was carried out to investigate the properties of bark extractives form Larix epilepsies and to evacuate their suitability as a bonding agent. The yield and reactivity were measured to examine the influence of temperature and time and the effect of carbonation and sulfonation. To define the possibility of practical application as wood adhesives the viscosity and gelation time were measured at 33% concentration. The results obtained were summarized as follows : 1. As the both yield and reactivity were high, extraction for 2 hours at $80^{\circ}C$ was the optimal temperature and time. 2. The highest effect achieved at 1% $Na_2CO_3$ about carbonation and 1% $Na_2SO_3$ : $NaHSO_3$ and 0.25% $Na_2SO_3$ about sulfonation. The sulfonation of 0.25% $Na_2SO_3$ increased the yield and reactivity most highly. 3. By using hot water as extraction liquid the yield was 17.2%, while the addition of 1% and 5% NaOH to the extraction liquid increased the yield to 38.6% and 44.6%, respectively. 4. Hot water extracts showed the highest reactivity(68.8%). The addition of 1% and 5% NaOH led to decrease in reactivity(49.3% and 25.8%, respectively). 5. At 33% concentration of the extracts the viscosity appeared very variable. Significantly high values of viscosity was measured in 1% NaOH solution, while very low values appeared for 5% NaOH solution. 6. The shortest gelation time was determined at pH 7 to 10 and the highest at pH 4. The use of paraformaldehyde resulted in gelation times longer than those of 37% formaldehyde solution. 7. Except the sulfonation extracts of hot water and 1% NaOH, the other extracts were found unsuitable due to high viscosity(1% NaOH extracts, sulfonation extracts) or to curing inability(5% NaOH extracts, sulfonation extracts of 5% NaOH). 8. From the three extract solutions which appeared to be suitable for use as bonding agents the hot water extracts and the sulfonation extracts of hot water were superior in extract reactivity, while the sulfonation extracts of 1% NaOH exceeded the other two extracts in extract yield.

• Journal of the Korean Institute of Navigation
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• v.4 no.2
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• pp.45-79
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• 1980

The aim of this paper is to analyze the mechanics of price formation in the tramp shipping. For the purpose of this study, the main characteristics of tramp freight rates and the market is examined, and a brief examination of the nature ofthe costs of operation is given which are essential for the understanding of the functioning of shipping firms as well as for the understanding of developments in the tramp freight market. The demand and supply relationships in the market is also analysed in detail. Tramp shipping is an industry that has a market which functions under conditions that are not dissimilar to the theoretical model of perfect competition. However, it does notmean that tramp shipping market is a perfectly competitive market. It is apparent that this realworld competitive system has its imperfections, which means that the market for tramp shipping is near to being a perfectly competitive market on an internaitonal scale and it is freight are therefore subjext to the laws of supply and demand. In theory, the minimum freight rate in the short term is that at which the lowest cost vessels will lay-up in preference to operating, and is equal to the variable costs minus lay-up costs; and this would imply that in all times except those of full employment for ships there is a tendency for newer low-cost, and, probably, faster vessels to be driving the older high-cost vessels in the breaker's yards. In this case, shipowners may be reluctant to lay-up their ships becasue of obligations to crews, or because they would lose credibility with shippers or financiers, or simply because of lost prestige. Mainly, however, the decision is made on strictly economic grounds. When, for example, the total operating costs minus the likely freight earnings are greater than the cost of taking the ship out of service, maintaining it, and recommissioning it, then a ship may be considered for laying-up; shipowners will, in other words, run the ships at freight earnings below operating costs by as much as the cost of laying them up. As described above, the freight rates fixed on the tramp shipping market are subject to the laws of supply and demand. In other words, the basic properties of supply and demand are of significance so far as price or rate fluctuations in the tramp freight market are concerned. In connection with the same of the demand for tramp shipping services, the following points should be brone in mind: (a) That the magnitude of demand for sea transport of dry cargoes in general and for tramp shipping services in particular is increasing in the long run. (b) That owning to external factors, the demand for tramp shipping services is capable of varying sharphy at a given going of time. (c) The demad for the industry's services tends to be price inelastic in the short run. On the other hand the demand for the services offered by the individual shipping firm tends as a rule to be infinitely price elastic. In the meantime, the properties of the supply of the tramp shipping facilities are that it cannot expand or contract in the short run. Also, that in the long run there is a time-lag between entrepreneurs' decision to expand their fleets and the actual time of delivery of the new vessels. Thus, supply is inelastic and not capable of responding to demand and price changes at a given period of time. In conclusion, it can be safely stated that short-run changes in freight rates are a direct result of variations in the magnitude of demand for tramp shipping facilities, whilest the average level of freight rates is brought down to relatively low levels over prolonged periods of time.

• Food Engineering Progress
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• v.21 no.3
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• pp.225-232
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• 2017

Most of the red ginseng (RG) products contain active substances derived from hot water or alcohol extraction. Since active substances of RG are divided into two types - water-soluble and liposoluble - water or alcohol is needed as an extraction solvent and this leads the different extraction yields and components of the active substances. To overcome the limit, whole red ginseng powder can be used and consumed by consumers. In this study, the physicochemical properties and extractable active substance contents of variable-sized RG powder ($158.00{\mu}m$, $8.45{\mu}m$, and $6.33{\mu}m$) were analyzed, and dispersion stability was measured to investigate the suitable size of RG powder for industrial processing. In the results, no significant difference was found from the changes in color intensity and thiobarbutric acid tests at $4^{\circ}C$, $25^{\circ}C$, and $40^{\circ}C$ for 4 weeks. There was no significant difference on the production of antioxidants and ginsenoside among the samples (p>0.05). In dispersion stability, $RG-158.00{\mu}m$ was precipitated immediately, and the dispersion stabilities between $RG-8.45{\mu}m$ and $RG-6.33{\mu}m$ showed no significant difference. It implies that fine RG is suitable for the production process. With further study, it seemed that the physicochemical effects of RG particle sizes can be clearly revealed.