• Korea Trade Review
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• v.48 no.1
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• pp.127-163
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• 2023

The objective of this study is to investigate the volatility spillover effects among BDI, CCFI and SCFI. This paper will divide the empirical analysis section into two periods to analyze and compare the differences in volatility spillover effect between shipping freight indices before and after the outbreak of COVID-19 separately. First, in order to compare the mean spillover impact and index lead-lag correlations in BDI and CCFI indices, along with BDI and SCFI indices before and after COVID-19, the co-integration analysis and the test of Granger causality built on the VAR model were utilized. Second, the impulse response and variance decomposition are employed in this work to investigate how the shipping freight index responds to shocks experienced by itself and other freight indices in a short period. Before the COVID-19 epidemic, the results demonstrated that the BDI freight index is the Granger cause of the variable CCFI freight index. But the BDI and CCFI freight indices have no apparent lead-lag relationships after COVID-19, and this empirical result echoes the cointegration test result. After the COVID-19 epidemic, the SCFI index leads the BDI index. This study employs the VAR-BEKK-GARCH joint model to explore the volatility spillover results between dry bulk and container transport markets before and after COVID-19. The empirical results demonstrate that after COVID-19, fluctuations in the BDI index still affect the CCFI index in the maritime market. However, there is no proof of a volatility spillover relationship between the BDI and SCFI after the COVID-19 epidemic. This study will provide an insight into the volatility relationship among BDI, CCFI and SCFI before and after the the COVID-19 epidemic occurred.

• Korean Journal of Plant Resources
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• v.25 no.1
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• pp.156-168
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• 2012

Chrysanthemum is a cut flower species that normally lasts for 1 to 2 weeks, in some cases 3-4 weeks. This has been attributed to low ethylene production during senescence. Reduction in cut flower quality has been attributed to the formation of air embolisms that partially or completely blocks the water transport from the vase solution to the rest of the cut flower stem, increasing hydraulic resistance which may cause severe water stress, yellowing, wilting of leaf, and chlorophyll degradation. Standard type chrysanthemum can be harvested when buds were still tightly closed and then fully opened with the simple bud-opening solution. Standard type chrysanthemum can also be harvested when the minimum size of the inflorescence is about 5-6 cm bud which opened into the first flower full-sized flower. While spray varieties can be harvested when 2-4 most mature flowers have opened (40% opening). Cut flowers are sorted by stem length, weight, condition, and so on. Standard chrysanthemum is 80 cm length for standard type and 70cm for spray type. Pre-treatment with a STS, plant regulator such as GA, BA, 1-MCP, chrysal, germicide, and sucrose, significantly improved the vase life and quality of cut flowers. It is well established that vase solutions containing sugar can improve the vase life of cut chrysanthemum. Chrysanthemum is normally packed in standard horizontal fiberboard boxes. Chrysanthemum should normally be stored at $5{\sim}7^{\circ}C$. Precooling resulted in reduction in respiration, decomposition, and transpiration activities as well as decoloration retardation. There was significant difference between "wet" storage in 3 weeks and "dry" storage in 2 weeks. In separate pulsing solution trials, various germicides were tested, as well as PGRs to maintain the green color of leaves and turgidity. Prolonging vase life was attained with the application of optimal solution such as HQS, $AgNO_3$, GA, BA and sucrose. This also retarded senescence in leaves of cut flower stems. Fresh cut chrysanthemum can be transported using a refrigerated van with $5{\sim}7^{\circ}C$. Increasing consumption and usage of cut chrysanthemum of various cultivars would require efficient transport system, and effective information exchange among producer, wholesaler, and consumer.

• Applied Microscopy
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• v.30 no.4
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• pp.357-365
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• 2000

Paneth cells have been suggested to contribute to the elimination of excess metals into the intestinal lumen. The purpose of this study wat to investigate the changes of the zinc pools in rats subjected to functional loading with zinc salt by mean of both light and electron microscopical autometallography (AMG). Wistar rats 4 were administrated with zinc chloride (20 mg/kg body weight) intraperitoneally dissolved in 1 ml distilled water. The control group received 1 ml saline IP. After further one hour the animals were transcardially perfused with 0.4% sodium sulphide dissolved in 0.1 M PB fellowed by 3% glutaraldehyde solution for 10 minutes. Pieces of ileum were frozen with solid $CO_2$ and sectioned on a cryostat. The sections $(20{\mu}m)$ were autometallographically developed. Sections selected for EM were reembedded on top of a blank Epon block, from which ultrathin sections (100 nm) were cut. The ultrathin sections were double stained with uranyl acetate (30 min) and lead citrate (5 min), then examined under electron microscope. Studies of comparable sections from control and zinc loaded animals with the AMG selenium method gave quite different results. The control animals demonstrated a weakly positive staining in the cytoplasm of the Paneth cells. In the electron microscope the AMG silver grains were found to be located in the cytoplasm, while the electron dense secretary granules and other cell organelles were void of staining. Few AMG grains were located at the apical surface of the Paneth cells. In sections from zinc loaded rats, the AMG grains were seen in abundance in the lumen of the Lieberkuhn crypts at light microscopic levels. At EM levels the zinc revealing silver grains were located in the cytoplasm as in the controls, but much more AMG grains were shifted into the secretary granules. Furthermore, profound AMG grains were found in the lumen of the crypts and surrounding vessels. And a few grains were seen in the endothelium. The AMG technique demonstrated a pattern of AMG grains in the Paneth cells that strongly suggests a transport of zinc ions through these cells.

• Journal of Bio-Environment Control
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• v.11 no.3
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• pp.127-132
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• 2002

Enhanced supply of $Ca^{2＋}$ as well as NO$_3$$^{[-10]}$ is known to restrict the uptake of the Na$^{＋}$ and Cl$^{[-10]}$ ion and ameliorate growth under saline conditions. This test was conducted to investigate the ameliorating effects of Ca(NO$_3$)$_2$ or CaCl$_2$ on the growth and yield of NaCl-stressed tomato plants grown in plastic pot filled with soil. All treatments except for the control were supplied with 80 mM NaCl fur two weeks after transporting. The saline solutions with nutrient were supplemented with either 0, 10 or 20 mM Ca(NO$_3$)$_2$ and either 0, 10 or 20 mM CaCl$_2$ during harvesting time from two weeks after transporting. Ca(NO$_3$)$_2$ or CaCl$_2$ application enhanced the growth such as plant height, fresh weight, dry weight, fruit number, and fruit weight, and yield of NaCl-stressed tomato, and also their effects increased greater as concentration of supplemented Ca(NO$_3$)$_2$ or CaCl$_2$increased. Yield increased in 20 mM Ca(NO$_3$)$_2$ compared with the others except fur the control. Photosynthetic rate in Ca treatments was lower than that of the control, but higher than that of NaCl treatment. Leaf chlorophyll content was higher in Ca treatments compared with the others, especially in younger leaf, while that was not affected by concentration of supplemented Ca. Ca(NO$_3$)$_2$ or CaCl$_2$ supply increased the $K^{＋}$ and $C^{2＋}$ concentration of tomato plants, whereas the Na$^{＋}$ transport to the leaves was inhibited. There was a strong increase in the $K^{＋}$/Na$^{＋}$ ratio in plants treated Ca(NO$_3$)$_2$, or CaCl$_2$. Cl$^{[-10]}$ content of plants was decreased by supplemental Ca(NO$_3$)$_2$ but Cl$^{[-10]}$ was increased in plants with CaCl$_2$compared with Ca(NO$_3$)$_2$. N concentration in plants of tomato increased with enhanced Ca(NO$_3$)$_2$ or CaCl$_2$supply, In conclusion, our study confirms the potential of Ca(NO$_3$)$_2$ or CaCl$_2$to alleviate NaCl-induced growth reductions in tomato.

• Journal of the Korean Geographical Society
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• v.29 no.3
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• pp.266-280
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• 1994

Upper-air synoptic data and surface weather elements such as temperature, relative humidity, wind speed, cloud and precipitation were analyzed in some detail to determine the characteristics of Nopsae, a foehn-like surface wind over the Youngsuh region of Central Korea. NOAA AVHRR and GMS images are also referenced to identify the distribution of clouds and precipitation to classify the tpyes of foehn over the study area. The data period examined is from 1982 until 1993 of spring and summer months from March through August. Results of the anaylsis are as follows. Warm and dry air penetration over the Younesuh region has experienced on foehn days occured between March 21 and August 10 during study perion. The mean annual number of foehn the days were 28. Foehn phenomena were prominent during March 21-25, April 5-15, May 25-June 10, and June 26-30 pentads. The intensity of the phenomena can be evaluated as the difference of daily maximum temperature and relative humidity between windward sites and leeward sites. The intensity of daily maximum temperature reached 14.5$^{\circ}C$, but most values were in the range of 5.0-7.5$^{\circ}C$ (61%). Although strong intensity of foehns usually develop in June, it is common that farmers in the region experince more aridity during the foehnday of April and May due to the transplantation of rice seedlings. Long-run foehn are not common phenomena and 55% of foehn terminate in one day, but there is a record that Nopsae persisted up to 9 days continuously. The author identified using the cloud and precipitation data out of NOAA-11, AVHRR and GMS images is that one of them has no precipitation over windward side. The available data and the results of the analysis are somewhat inadequate. Since the results imply that wave phenomenon is potentially important in terms of local surface weather and vertical momentum transport, more detailed theoretical and observational studies are necessary to clarify the mechanism and the impacts of Nopsae.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.463-470
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• 2012

As the advanced seeding technology through use of plug tray for good cultivation of seeds was propagated along with the expansion and development of horticultural industry, the use of bed soils as growing medium has recently been increased. In this study, the effects of the four clay minerals such as illite, phyllite, zeolite, and bentonite on the early growth of red pepper in the bed soil were investigated. Furthermore, proteome analysis for the leaf and stem samples of red pepper treated with only illite was performed. Of the seedling cultured, the healthy and regular size seeds were selected and cultivated in the pots, after they were treated with four clay minerals. The experiment was performed during the whole six weeks in the glasshouse of the Chungbuk National University. The growth lengths, fresh and dry weights of red pepper were significantly higher in the treatments of illite, phyllite, zeolite, and bentonite than in the control. In addition, the uptake of $K^+$, $Ca^{2+}$, and $Mg^{2+}$ were higher in the treatment of illite, phyllite, zeolite, and bentonite than in the control. The 2-DE patterns for the red pepper by the applications of illite, phyllite, zeolite, and bentonite were similar to each other. Therefore, compared to the samples of control, the proteome analysis for the samples of red pepper treated by only illite were performed. Proteome analysis for red pepper showed that plastid fructose-1, 6-bisphosphate aldolase class 1, aldolase, and glyceraldehydes 3-phosphate dehydrogenase, all of which were involved in the energy metabolism, were highly expressed in leaf tissue by illite treatment. In stem tissue, NAD-dependent formate dehydrogenase involved in energy metabolism, potassium transport protein, and GIA/RGA-like gibberellins response modulator were highly expressed. Based on the results obtained from the proteome analysis, it appears that the proteins specifically and differentially expressed on the illite treatment may be involved in the enhanced growth of red pepper. The identification of some proteins involved in the response of vegetable crops to the treatment of clay mineral can provide new insights that can lead to a better elucidation and understanding of mechanism on their molecular basis.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.422-431
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• 2019

Severe droughts in spring have occurred frequently in Korea in recent years, exerting a critical impact on corn yield. Therefore, it is necessary to find physiological and/or molecular indicators of the response to drought stress in maize plants. In this study, we investigated the effects of water-deficit stress on two Korean elite F₁ maize hybrids, Ilmichal and Gwangpyeongok, by withholding water for 10 days at tassel initiation. The water deficit drastically reduced the relative leaf water content, leaf number, leaf area, and stem length, leading to dry matter reduction. Moreover, it reduced the SPAD values and stomatal conductance of leaves in drought-stressed plants of both hybrids. Importantly, the number of leaves and SPAD value were non-destructive and easy to investigate in response to water-deficit stress, suggesting that they may be useful indicators for screening drought-tolerant genetic resources. We detected more than 100 spots that were differentially accumulated under drought stress. Of these spots, a total of 21 protein spots (≥1.5-fold) from drought-exposed maize leaves were successfully analyzed by MALDI-TOF-TOF mass spectrometry. Functional annotation using Gene Ontology analysis revealed that most of the identified proteins were involved in carbohydrate metabolism, stress response fatty acid catabolism, photosynthesis, energy metabolism, and transport. The protein expression levels were increased in both Ilmichal and Gwangpyeongok, except for triosephosphate isomerase, fructose-bisphosphate aldolase, and an uncharacterized protein. The lactoylglutathione lyase delta (3,5)-delta (2,4)-dienoyl-CoA isomerase was overexpressed in Gwangpyeongok only. The results obtained from this study suggest that the drought-specific genes may be useful as molecular markers for screening drought-tolerant maize genotypes.