• Ocean and Polar Research
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• v.41 no.4
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• pp.233-250
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• 2019

A re-assessment of the age structure of the population of the Antarctic icefish Pseudochaenichthys georgianus based on body length data covering the years 1976-2009 and including larvae and postlarvae collected in 1989 and 1990 allowed us to define age groups 0, I, and II as containing fish with respective body lengths of 6-9 cm, 15-27 cm and 27-39 cm. Age at maturity (first spawning) was found to occur in age group III at body lengths that have been falling from 50.1 cm in 1979 to 45.4 cm in 1992. Considering postlarvae together with adult fish, the v. Bertalanffy growth curve parameters were determined as L_∞ = 60.62 cm, k = 0.4, t₀ = 0.25. Although the reasons for a maturity at shorter body lengths is not fully understood a host of environmental factors like increasing water temperatures and possibly changes in currents, interspecific competition, food availability, etc. are likely to be involved. Global warming (and not primarily overfishing) is likely to have been responsible for the disappearance of larger fish in the surface waters of South Georgia since 1977, for virtually all commercial fishing stopped in the early 1990s. On the other hand, the appearance of numerous younger spawning individuals suggests that larvae do survive in the colder deeper water below 200 m. The biomass of Ps. georgianus oscillates with a 4-year periodicity in contrast to that of the coexisting icefish Chaenocephalus aceratus: the former with a lower biomass in warm years and a higher one in cold years. The biomass of the third species of icefish in the region, i.e. Champsocephalus gunnari, also oscillates, but with a longer periodicity than that involved in the biology of the other two and its biomass increases in contrast to the other two species. The result is that the biomass all three species considered together is rather stable.

• Wind and Structures
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• v.20 no.4
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• pp.509-525
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• 2015

A three-dimensional aerodynamic model and a vehicle dynamics model are established to investigate the effect of noise barrier on the dynamic performance of a high-speed train running on an embankment in crosswind in this paper. Based on the developed model, flow structures around the train with and without noise barrier are compared. Effect of the noise barrier height on the train dynamic performance is studied. Then, comparisons between the dynamic performance indexes of the train running on the windward track and on the leeward track are made. The calculated results show that the noise barrier has significant effects on the structure of the flow field around the train in crosswind and thus on the dynamic performance of the high-speed train. The dynamic performance of the train on the windward track is better than that on the leeward track. In addition, various heights of the noise barrier will have different effects on the train dynamic performance. The dynamic performance indexes keep decreasing with the increase of the noise barrier height before the height reaches a certain value, while these indexes have an inverse trend when the height is above this value. These results suggest that optimization on the noise barrier height is possible and demonstrate that the designed noise barrier height of the existing China Railway High-speed line analysed in this article is reasonable from the view point of the flow field structure and train dynamic performance although the noise barrier is always designed based on the noise-related standard.

• Environmental and Resource Economics Review
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• v.14 no.1
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• pp.221-235
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• 2005

In this paper, we analyzed the dynamic structure of optimal tariff levied on importing non-renewable resources such as petroleum, iron, coal, etc. According to the previous literature that have studied this objective, the time inconsistent open loop tariff has been suggested to be imposed in order to improve the welfare level of importing country. We set up the efficient model to identify how to impose the optimal tariff over time. Based on this model, we have found that the previous literature ignored that the costate variable for the stock for non-renewable resource decomposed between the scarcity effect and the cost effect. On the basis of the role of costate variable, we, however, have found that the proposition of the previous literature has led into errors. Hence, we suggest that the dynamically consistent open loop tariff for non-renewable resources would improve the welfare level of importing country.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.94-101
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• 2008

In Korean waters, there are two color types (blue and purple) of the blue crab Portunus trituberculatus. The blue type is common, but the ratio of the purple type has increased in landings. To determine whether there were significant morphometric or genetic differences between the blue and purple types, crabs caught from the West Sea of Korea were examined. Based on covariance analysis, there were significant differences in 1 of 10 morphometric characteristics of males between the two types, in none of the ten characteristics for females. Using amplified fragment length polymorphism (AFLP) DNA fingerprinting, no specific AFLP marker was detected for each type. The heterozygosity and genetic diversity were very low. Analyses of pairwise distance, the Fst index, and genetic similarity revealed similar results, with very low genetic differentiation. Therefore, there is no significant difference between blue and purple types of the crab from the West Sea of Korea, and the two types in the West Sea can be managed as one stock.

• Journal of the Korea Society of Computer and Information
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• v.8 no.2
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• pp.145-154
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• 2003

Business environment is changing rapidly because of the introduction of the newest Technologies development and the newest management skills. With the development of Information Technology (IT) and the rapid growth of Internet based business, there have been great improvements of business processes and total costs of many firms. Many firms realize that they have to change their organizational structure and managerial skills in order to carry on their corporate goals(growth and development) according to business paradigm shift. The purpose of this dissertation is to watch how consumer product manufacturer(C corporation) could build effective SCM strategies under Electronic Commerce paradigm shift and how it can reform its organizational structure in order to perform its business goat. C corporation has been doing a groat role in logistics and distribution for the last 50 years with logistics know-how in domestic market, however there were many problems such as lack of shared information, demand Paradox, order batch, stock shortage and duplicated processes among vendors and chain members. Most of problems were based on lack of shared information and old business processes.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.334-340
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• 2002

$TiO_2$-coated fly ash was synthesized by dropping method of coating agent in order to get $TiO_2$ coating layer with high photocatalytic activity on the surface of coal fly ash. The properties of the $TiO_2$ coating layer such as morphology, crystal structure, crystal size and photocatalytic activity were compared with those of the $TiO_2$-coated fly ash prepared by the traditional method of precipitation. $TiCl_4$ aqueous solution was used as a titanium stock solution and $NH_4HCO_3$ was used as a precipitant. The $TiO_2$ coating layer obtained by dropping method of coating agent was more uniform than that coated by precipitation. However, the crystal of $TiO_2$ coated by dropping method of coating agent was easy to grow by heat treatment because of the small primary particle size and bulky morphology, and its photocatalytic activity was consequently lower than that of the $TiO_2$ coated by precipitation. The $TiO_2$ coating layer obtained by both methods had a crystal structure of anatase, and the temperature of phase transformation into rutile was 90$0^{\circ}C$. The minimum crystal size of $TiO_2$ for the highest photocatalytic activity was found to be about 10nm.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.149-158
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• 1998

Volcanic rocks including rhyolitic tuff, rhyolite and welded tuff in the Bupyeong silver mine area form a topographic circular structure known as a resurgent caldera. Granitic rocks are emplaced inside and outside area of the circular structure. K-Ar dating and Nd-Sr isotope studies were carried out to invesitigate the origin and petrogenetic evolution of the rhyolitic and granitic magma in the Bupeong silver mine area. Whole rock K-Ar age ranges from 208 to 131 Ma for rhyolitic rocks. Radiometric ages for the granitic rocks are 167.6 Ma for pink feldspar biotite granite from inside granitic pluton of the circular volcanic body, 178.8 Ma for the Kimpo hornblende biotite granite and 111.8 Ma for the Songdo foliated granite from outside granitic plutons of the volcanic body. The radiometric age data indicates that the volcanic activities which are partly overlapped by granite plutonic activities in the Bupyeong mine area had recorded early Jurassic and early Cretaceous in age. Initial Sr and Nd isotopic ratios of the rhyolitic rocks ($^{87}Sr/^{86}Sr$=0.710~0.719 and $^{143}Nd/^{144}Nd$=0.5115~0.5118) are similar to those of granitic rocks ($^{87}Sr/^{86}Sr$=0.709~0.716 and $^{143}Nd/^{144}Nd$=0.5115~0.5116) from inside granite stock. This means that similar source materials of felsic magma responsibles for the Bupyeong volcanic rocks and inside plutonic rocks. Based on the Nd and Sr isotopic compositions, rhyolitic and granitic magmas in the Bupyeong area originated from the partial melting of the old continental crust which has Nd model age ranging from 1500 to 2900 Ma. This is analogous to those of the other Jurassic granitoids in South Korea.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.80-87
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• 2021

Most container ships are currently being constructed as Ultra-Large Container Ships. Hence, the equipment of the ships is also becoming relatively large. In particular, propellers, rudders, and rudder stocks are large in the stern structure, and in relation, efficient design of the hull structures to safely secure these parts is important. The bottom shell plate surface of a stern skeg is a perforated plate from which the rudder stock penetrates, so it is an important component for the stern structure. In this paper, to determine the critical buckling of the shell plate, an interaction curve equation for the two-axis compression of the shell plate was derived using the maximum value of the static structural stress multiplier in a load multiplier mode. This equation predicts the timing of the buckling occurrence. By analyzing this interaction curve equation, the buckling behavior of the plates subjected to a combination load was determined and the usefulness of applying it to ship building was investigated.

• International Area Studies Review
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• v.21 no.4
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• pp.19-39
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• 2017

The purpose of this paper is to investigate the impact of terms of trade and its volatility on real GDP and inflation. I estimate the linear and dynamic panel model including variables such as real GDP, inflation, terms of trade, capital stock, employment and education. The sample countries consist of OECD 26 countries and panel data ranges from 1990 to 2015. The empirical results show that terms of trade and its volatility do not affect the real GDP significantly. Even if the terms of trade has a negative relationship with real GDP, the magnitude of the estimated coefficients was very small. This result seems to be related with the industry structure and domestic demand structure of the member countries. On the other hand, terms of trade and its volatility have the significant impact on inflation. When the terms of trade and its volatility increase, the inflation increases.

• The Journal of Economics, Marketing and Management
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• v.11 no.4
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• pp.19-30
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• 2023

Purpose: This study examines the factors that the Millennials and Gen Z prefers to invest in assets. We look at the asset structure they want now and in the future and the idea of designing the future. This can be expected that the center of Korea's asset market will change to the structure they want in the future. Research design, data and methodology: The spatial extent of the study is all over Korea including Seoul, the metropolitan area, and local cities. The survey was conducted for about 16 days from May 7 to May 22, 2023. The survey was conducted by the surveyor visiting the subject in person, distributing the questionnaire, explaining it, and filling it out in person. For the analysis, descriptive statistics and logistic regression analysis were conducted using the SPSS 25.0 statistical package. Results: It was confirmed that the preferred assets of the Millennials and Gen Z were different by period. There was also a difference in the influencing factors between Millennial Generation and Generation Z in asset preference. Conclusions: The Millennials and Gen Z's preferred assets were different by period. The reason is interpreted as the current process of collecting assets during the asset formation period. In the future, they intend to purchase real estate assets by using financial assets as a lump sum of money. We learned the characteristics of the entire Millennials and Gen Z, in addition, the difference between income and assets is believed to have affected the difference in preference factors of Millennial Generation and Generation Z, respectively.