• Title/Summary/Keyword: fluctuations

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Groundwater Level Responses due to Moderate·Small Magnitude Earthquakes Using 1Hz groundwater Data (1Hz 지하수 데이터를 활용한 중·소규모 지진으로 인한 지하수위 반응)

  • Gahyeon Lee;Jae Min Lee;Dongkyu Park;Dong-Hun Kim;Jaehoon Jung;Soo-Hyoung Lee
    • Journal of Soil and Groundwater Environment
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    • v.29 no.4
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    • pp.32-43
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    • 2024
  • Recently, numerous earthquakes have caused significant casualties and property damage worldwide, including major events in 2023 (Türkiye, M7.8; Morocco, M6.8) and 2024 (Noto Peninsula, Japan, M7.6; Taiwan, M7.4). In South Korea, the frequency of detectable and noticeable earthquakes has been gradually increasing since the M5.8 Gyeongju Earthquake. Notable recent events include those in Jeju (M4.9), Goesan (M4.1), the East Sea (M4.5), and Gyeongju (M4.0) since 2020. This study, for the first time in South Korea, monitored groundwater levels and temperatures at a 1Hz frequency to observe the responses in groundwater to moderate and small earthquakes primarily occurring within the country. Between April 23, 2023, and May 22, 2023, 17 earthquakes were reported in the East Sea region with magnitudes ranging from M2.0 to M4.5. Analysis of groundwater level responses at the Gangneung observation station revealed fluctuations associated with five of these events. The 1Hz observation data clearly showed groundwater level changes even for small earthquakes, indicating that groundwater is highly sensitive to the frequent small earthquakes recently occurring in South Korea. The analysis confirmed that the maximum amplitude of groundwater level changes due to earthquakes is proportional to the earthquake's magnitude and the distance from the epicenter. These findings highlight the importance of precise 1Hz-level observations in earthquake-groundwater research. This study provides foundational data for earthquake monitoring and prediction and emphasizes the need for ongoing research into monitoring the changes in groundwater parameters (such as aquifer characteristics, quantity/quality, and contaminant migration) induced by various magnitudes of earthquakes that may occur within the country in the future.

A study on Securing Port Competitiveness through analysis of General Cargo Volume at Busan Port (부산항의 일반 화물 물동량 분석을 통한 항만 경쟁력 확보에 관한 연구)

  • Shin, Hak-Sung;Cho, Sang-Lee
    • Journal of Korea Port Economic Association
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    • v.39 no.4
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    • pp.295-308
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    • 2023
  • Busan Port, as Korea's representative trading port, handles a variety of port cargo from bulk cargo to container cargo. Busan Port is currently functioning as a container specialized port for North Port and Busan New Port, and Gamcheon Port is also handling container cargo mainly in bulk cargo. This study intends to examine the overlapping cargoes and specialized cargoes between these ports and Busan Port as the amount of import and export cargoes in ports designated as trade ports in Korea is increasing. In order to understand the characteristics of the major cargoes handled in the port, the quantitative change is confirmed through the total cargo volume of major domestic ports and the trend of changes in import/export cargo between Busan Port and major ports is analyzed. There are many specialized investigation methods, but as the most basic method, we will examine quantitative changes and causes by simply examining the data for 10 years as the amount of change by cargo. In addition, the causes of these fluctuations should be reclassified into domestic and foreign causes by identifying changes in customers in different ports and shipping volumes, changes in consumption areas, and transshipment volumes. Through the analysis of the major cargo volume of each port, the characteristics and fluctuation trends of major cargo handled in Busan Port and other ports are identified, and the competitive cargoes of each port are verified. Through this, the characteristics and competitiveness of the port are inferred, and implications for the cargo volume of Busan Port and future countermeasures are suggested.

Analysis of Price Fluctuation Factors in the Vessel Demolition Market : Focusing on India & Bangladesh (선박 해체시장 가격 변동 요인 분석 : 인디아, 방글라데시를 중심으로)

  • Lee ChongWoo;Jang Chul-Ho
    • Journal of Korea Port Economic Association
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    • v.39 no.4
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    • pp.243-254
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    • 2023
  • This study investigates the factors contributing to price fluctuations in the shipscrapping market, the final stage in a vessel's life cycle. Shipping companies make decisions on ship dismantling based on factors such as declining freight rates, increasing vessel age leading to higher costs, or compliance with new environmental regulations. Utilizing the FMOLS (Fully Modified Ordinary Least Squares) and VECM (Vector Error Correction Model) methodologies, the research explores the long-term elasticities of factors influencing shipscrapping prices and examines short-term causal relationships. Using a time series dataset spanning from December 2015 to April 2023, covering a total of 90 months, the study focuses on the shipscrapping prices of Capesize vessels in India and Bangladesh, which constitute a significant portion of the shipbreaking market. The findings indicate that, in the long term, shipscrapping prices are closely related to global scrap prices, 20-year-old secondhand Capesize vessel prices, newbuilding prices, and exchange rates. In terms of short-term causal relationships, an increase in global scrap prices induces a rise in shipscrapping prices, while the remaining variables do not contribute to such increases. Specifically, an escalation in shipscrapping prices is associated with increased prices of 20-year-old secondhand vessels, newbuilding prices, and exchange rates. However, the other variables do not show a significant influence on short-term increases in shipscrapping prices.

The Effect of BDI on the Network Connectedness of Shipping Companies: Focusing on CoVaR Network Connectedness (BDI가 해운선사 네트워크 연계성에 미치는 영향: CoVaR 네트워크 연계성을 중심으로)

  • Jung, Dae-Sung ;Choi, Ki-Hong
    • Journal of Korea Port Economic Association
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    • v.39 no.4
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    • pp.269-283
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    • 2023
  • Based on daily data from January 4, 2016 to September 27, 2022, the impact of extreme movements of BDI on shipping companies' network connectivity was analyzed using CoVaR network connectivity. The main results and policy implications are as follows. First, according to the copula model results, the Student-t copula was selected as the most suitable model for COSCO, HMM, HRAG, MAERSK, and WAN. EVER was selected as a time-varying Gumbel copula, and YANG was selected as a time-varying rotated-Gumbel copula. Second, as a result of analysis using the TVP-VAR model, the linkage between shipping companies tended to increase when the BDI turned into an extreme risk state. In the comparison of net connectivity, the roles of COSCO and EVER changed. In addition, in the analysis of net pairwise connectivity, it was found that the change in the extreme risk state of BDI also affected the connectivity of shipping companies. In particular, EVER, WAN, and COSCO showed large changes. Taken together, the extreme fluctuations in BDI changed the role of Asian shipping companies, intensifying competition among shipping companies and strengthening risk delivery. It was confirmed that BDI has a great influence on the network connectivity of shipping companies and has an important influence on the stability of the stock market network. Therefore, the results of this study should consider not only the connectivity of shipping companies according to market conditions, but also the connectivity in extreme situations.

Temperature Prediction and Control of Cement Preheater Using Alternative Fuels (대체연료를 사용하는 시멘트 예열실 온도 예측 제어)

  • Baasan-Ochir Baljinnyam;Yerim Lee;Boseon Yoo;Jaesik Choi
    • Resources Recycling
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    • v.33 no.4
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    • pp.3-14
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    • 2024
  • The preheating and calcination processes in cement manufacturing, which are crucial for producing the cement intermediate product clinker, require a substantial quantity of fossil fuels to generate high-temperature thermal energy. However, owing to the ever-increasing severity of environmental pollution, considerable efforts are being made to reduce carbon emissions from fossil fuels in the cement industry. Several preliminary studies have focused on increasing the usage of alternative fuels like refuse-derived fuel (RDF). Alternative fuels offer several advantages, such as reduced carbon emissions, mitigated generation of nitrogen oxides, and incineration in preheaters and kilns instead of landfilling. However, owing to the diverse compositions of alternative fuels, estimating their calorific value is challenging. This makes it difficult to regulate the preheater stability, thereby limiting the usage of alternative fuels. Therefore, in this study, a model based on deep neural networks is developed to accurately predict the preheater temperature and propose optimal fuel input quantities using explainable artificial intelligence. Utilizing the proposed model in actual preheating process sites resulted in a 5% reduction in fossil fuel usage, 5%p increase in the substitution rate with alternative fuels, and 35% reduction in preheater temperature fluctuations.

Fluctuations in Abundance and Species Composition of Fishes Collected by Both Sides Fyke Net in Dol-san, Yeosu (여수 돌산도 연안 이각망에 어획된 어류의 종조성 및 양적변동)

  • Jeong, Hyun-Ho;Han, Kyeong-Ho;Kim, Chun-Chel;Yoon, Seung-Min;Seo, Won-il;Hwang, Seon-Yeong;Lee, Sung-hun
    • Korean Journal of Ichthyology
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    • v.17 no.1
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    • pp.64-72
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    • 2005
  • The data for the present study were collected from the both-sides fyke net fishery in coastal Dolsan, Korea, from March 2003 to February 2004 A total of 2,402 individuals (432,42 kg) were collected and identified to 11 orders, 34 families, and 48 species. The most dominant order was the Perciformes, comprising 21 species in 15 families, followed by Scorpaeniformes, 8 species in 5 families, and Pleuronectiformes, 5 species in 3 families, These three orders constituted 67.9% of the total collected fish. The most dominant species, Acanthopagrus schlegeli, accounted for 279 individuals (20.26 kg), followed by Mugil cephalus with 187 individuals (99.61 kg), and Konosirus punctatus with 178 individuals (8.89 kg). The diversity index of the fish catches was 1.6823~2.9105 and was the highest in September 2003 and the lowest in December 2003. The evenness index was 0.6585~0.8872 it was the highest in August 2003 and the lowest in December 2003. The dominance index was 0.2000~0.6852, with the highest in December and the lowest in August 2003.

Studies on Changes of the Activity of the Hepatic cells, and Variations of Protein and Nucleic Acid Contents of the Liver Tissue with the Ovarian Development Phase of Female Boleophthalmus pectinirostris(Linnaeus) (자성(雌性) 짱뚱어, Boleophthalmus pectinirostris(Linnaeus)의 난소(卵巢) 발달단계(發達段階)에 따른 간세포(肝細布)의 활성변화(活性變化) 및 간조직(肝組織)의 단백질(蛋白質), 핵산함량(核酸含量)에 관(關)한 연구(硏究))

  • Chung, Ee-Yung;Lee, Keun-Kwang;Oh, Young-Nam
    • Korean Journal of Ichthyology
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    • v.3 no.1
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    • pp.48-57
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    • 1991
  • Changes of the activities of the hepatic cells of female mud skipper, Boleophthalmus pectinirostris were investigated under transmission electron microscopy. Monthly changes of gonadosomatic index(GSI) and hepatosomatic index(HSI), variations of protein and nucleic acid contents(total RNA and DNA) of the liver tissues with the gonadal development phase were also studied. GSI began to increase from May(the growing stage), reaching the maximum value in late June(the mature stage), and then it began to decrease from late July(the degenerative stage), reaching the lowest value in late September. Monthly variations of HSI were negatively related to GSI. HSI decreased in the summer season when the ovary was getting mature and reached the maximum in mid October when the ovary was degenerating. In June(the mature stage), the female hepatic cells of the liver tissues became large and nuclei were hypertrophic. The amounts of glycogen particles and lipid droplets in the cells gradually decreased, while a number of granular endoplasmic reticulum increased. It was assumed that well-developed granular endoplasmic reticulum binding ribosomes are supposed to play the leading role in protein synthesis and deposition for vitellogenin in the cytoplasm. In July(the spawning period), glycogen particles and lipid droplets gradually increased, and then these substances were still observed in large quantity in August(the degenerative stage). The protein contents of the liver tissues with the gonadal phases of the ovaries were shown the maximum value($4.720{\pm}0.103\;mg/g$) in June, and afterwards gradually decreased being the minimum($3.640{\pm}0.130\;mg/g$) in July, and then gradually increased in August. The mean total RNA contents per gram of the liver tissues appeared the maximum($0.523{\pm}0.040\;mg/g$) in June, and afterwards gradually decreased to the minimum($0.158{\pm}0.006\;mg/g$) in July and slightly increased in August again. From these results, it could be assumed that protein contents were closely related to RNA contents. The mean total DNA contents per weight (gr) of the liver tissues appeared to be similar although there were some monthly fluctuations. The ratio of the mean total RNA/DNA were 0.745 in June, 0.262 in July, 0.341 in August respectively.

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Overview of Major Oil Spill at Sea and Details of Various Response Actions -1. Number and Volume of Marine Oil Spills in Korea and in the World (대형 기름유출사고와 방제조치에 관한 연구 -1. 국내외 해양기름오염사고 건수와 유출량)

  • Kim, Kwang-Soo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.19 no.2
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    • pp.129-137
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    • 2013
  • In order to obtain quantitative basic data for marine oil pollution prevention, the statistics of oil spill incidents in Korea and in the world for 20 years from 1993 to 2012 were collected and analyzed with relation to the number of oil spills and the amount of oil spilt. In Korea for 20 years, total number and average annual number of oil spills were 6,608 cases and nearly 330 cases/year, respectively, and total volume and average annual volume of oils spilt were 57,328 kL and nearly 2,866 kL/year, respectively. Due to major oil spills from oil tankers, annual volumes of oils spilt in Korea were sharply increased to 15,388 kL in 1993, 15,773 kL in 1995, 3,428 kL in 1997 and 13,008 kL in 2007. In case of worldwide oil spills for 20 years, total number and average annual number of oil spills of 8 kL (or 7 tonnes) and above were 420 cases and 21 cases/year, respectively, and total amount and average annual amount of oils spilt 8 kL (or 7 tonnes) and above were about 800,000 kL (or 704,000 tonnes) and about 40,000 kL/year (or 35,200 tonnes/year), respectively. Major oil spills from oil tankers increased massively annual amounts of oils spilt worldwide to about 159,000 kL (or 140,000 tonnes) in 1993, about 147,600 kL (or 130,000 tonnes) in 1994, about 90,900 kL (80,000 tonnes) in 1996, about 81,800 kL (72,000 tonnes) in 1997 and about 76,100 kL (or 67,000 tonnes) in 2002. Obvious correlation between annual number of oil spills and annual amount of oil spilt was not found in both Korea and the world, while both annual number and annual volume tended to decrease with the lapse of year in both Korea and the world, though there were wide fluctuations from year to year in both annual number of oil spills and annual amount of oils spilt worldwide and in Korea for 20 years. From 2008 to 2012 worldwide, there were sharp decreases in both annual number and annual amount of oil spills. In particular, no oil spill of 800 kL (or 700 tonnes) and above occurred in the year of 2012.

Effect of Heating by Infrared Heating Lamps on Growth of Strawberry and Heating Cost (적외선 난방등을 이용한 난방이 딸기의 생육과 난방비에 미치는 영향)

  • An, Jae Uk;An, Chul Geon;Hwang, Yeon Hyeon;Yoon, Hae Suk;Chang, Young Ho;Shon, Gil Man;Jeong, Byoung Ryong
    • Journal of Bio-Environment Control
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    • v.22 no.4
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    • pp.355-360
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    • 2013
  • Diesel-burning air heater (air heater) and infrared heating lamp (infrared heater) were installed as auxiliary heaters in two single water-curtained plastic greenhouses with a set night temperature of $6^{\circ}C$ for cultivation of strawberry 'Seolhyang'. The average night air temperature was $6.6^{\circ}C$ in the infrared heater treatment and $7.1^{\circ}C$ in the air heater treatment. However, when the minimum outside temperature fell below $-10^{\circ}C$, the air heater had less internal temperature fluctuations. In contrast, the infrared heater had some cases of falling below the set temperature. The relative humidity was higher than 98% by the side-effect of water-curtain system regardless of the heating system. There was about $5^{\circ}C$ difference in leaf temperature between the turned-on and -off state of the infrared heater, and the efficacy of the infrared heater on leaf temperature was only limited to about 4 meters from the system. Peduncle length and plant height in the infrared heater tended to be greater than those in the air heater. There was, however, no statistically difference in leaf size and numbers of leaves, flowers on first cluster and branches. There was no difference in soluble solids content, fruit firmness, average fruit weight of the harvested fruits, and the yield. Comparing the heating costs, the air heater system took 622,662 won based on 543 L tax-free diesel, while the infrared heater system took 235,284 won by consuming 5,685 kWh of electricity, and 62.2% heating costs saving was achieved.

Foreign Entry Strategies for Korean Fishery Firms (한국수산업의 해외진출전략에 관한 연구)

  • 김회천
    • The Journal of Fisheries Business Administration
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    • v.15 no.1
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    • pp.131-153
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    • 1984
  • Fishery resources are still abundant compared with other resources and the possibility of exploitation is probably great. The Korean fishery industry has grown remarkably since 1957, and Korea is ranked as one of the major fishery countries. Its of fishery products reached the 9th in the world and the value of exports was 5th in 1982. But recently a growth rate has slowed down, due to the enlargement of territorial seas by the declaration of the 200 mile, Exclusive Economic Zone, the tendency to develop fishery resources strate-gically in international bargaining, the change in function of the international organizations, the expansion of regulated waters, the illegal arrest of our fishing boats, the rapid rise in oil prices, and the fall in fish prices, the development of fishery resources as a symbol of nationalism, the fishing boats decreptitude, the rise of crew wages, regulations on fishing methods, fish species, fishing season, size of fish, and mesh size, fishing quotas and the demand of excessive fishing royalties. Besides the the obligation of coastal countries, employing crews of their host countries is also an example of the change in the international environment which causes the aggravation of foreign profit of fishing firms. To ameliorate the situation, our Korean fishery firms must prepare efficient plans and study systematically to internationalize themselves because such existing methods as conventional fishing entry and licence fishing entry are likely to be unable to cope with international environmental change. Thus, after the systematic analysis of the problem, some new combined alternatives might be proposed. These are some of the new schemes to support this plan showing the orientation of our national policy: 1. Most of the coastal states, to cope with rapid international environmental change and to survive in the new era of ocean order, have rationalized their higher governmental structure concerning the fishery industries. And the coastal countries which are the objectives of our expecting entry, demand excessive economic and technical aid, limit the number of fishing boats’entry and the use of our foreign fishing bases, and regulate the membership of the international fishery commissions. Especially, most of the coastal or island countries are recently independent states, which are poorer in national budget, depend largely on fishing royalties and licence entry fees as their main resources of national finance. 2. Alternatives to our entry to deep sea fishing, as internationalization strategies, are by direct foreign investment method. About 30 firms have already invested approximately US $ 8 million in 9 coastal countries. Areas of investment comprise the southern part of the Atlantic Ocean, the Moroccan sea and five other sea areas. Trawling, tuna purse seining and five other fields are covered by the investment. Joint-venture is the most prominent method of this direct investment. If we consider the number of entry firms, the host countries, the number of seas available and the size of investment, this method of cooperation is perhaps insufficient so far. Our fishery firms suffer from a weakness in international competitive ability, an insufficiency of information, of short funds, incompetency in the market, the unfriendliness of host coastal countries, the incapability of partners in joint-ventures and the political instability of the host countries. To enlarge our foreign fishing grounds, we are to actively adopt the direct investment entry method and to diversity our collaboraboration with partner countries. Consequently, besides proper fishing, we might utilize forward integration strategies, including the processing fied. a. The enterprise emigration method is likely to be successful in Argentina. It includes the development of Argentinian fishing grounds which are still not exploited in spite of abundant resources. Besides, Arentina could also be developed as a base for the exploitation of the krill resources and for further entries into collaboration with other Latin American countries. b. The co-business contract fishing method works in American territorial seas where American fishermen sell their fishery products to our factory ships at sea. This method contributes greatly to obtaining more fishing quotas and in innovation bottom fishing operation. Therefore we may apply this method to other countres to diffuse our foreign fishing entry. c. The new fishing ground development method was begun in 1957 by tuna long-line experimental fishing in the Indian Ocean. It has five fields, trawling, skipjack pole fishing and shrimp trawling, and so on. Recently, Korean fisheries were successful in the development of the Antarctic Ocean krill and tuna purse seining. 3. The acceleration of the internationalization of deep sea fishing; a. Intense information exchange activities and commission participation are likely to be continues as our contributions to the international fishery organizations. We should try to enter international fishery commissions in which we are not so far participating. And we have to reform adequately to meet the changes of the function of the international commissions. With our partner countries, we ought to conclude bilateral fishery agreements, thus enlarging our collaboration. b. Our government should offer economic and technical aids to host countries to facilitate our firms’fishery entry and activities. c. To accelerate technical innovation, our fishery firms must invest greater amount in technical innovation, at the same time be more discriminatory in importing exogeneous fishery technologies. As for fishing methods; expanded use of multi-purpose fishing boats and introduction of automation should be encuraged to prevent seasonal fluctuations in fishery outputs. d. The government should increases financial and tax aid to Korean firms in order to elevate already weak financial structure of Korean fishery firms. e. Finally, the government ought to revise foreign exchange regulations being applied to deep sea fishery firms. Furthermore, dutes levied on foreign purchaed equipments and supplies used by our deep sea fishing boats thould be reduced or exempted. when the fish caught by Korean partner of joint-venture firms is sold at the home port, pusan, import duty should be exempted.

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