Among the different types of seaweed that are cultivated in Korea for food, Capsosiphon fulvescensis the filamentous green alga with the highest production value. However, its harvest yield varies significantly from year to year due to its dependence on the natural seeding method. The present study aimed to identify the conditions affecting the formation of cyst-zygotes that can be utilized as artificial seeds during the life cycle of C. fulvescens. Gametangia and zygotes of C. fulvescens were found to be highly developed at temperatures above 15°C, with a maximum gametangial development rate of about 35% observed after 7 days of culture. The formation of zygotes into cystzygotes was induced within 7 days in all temperature conditions, but after 30 days of culturing, cyst-zygotes germinated into filamentous thalli at temperatures above 20°C, while the most stable formation and stabilization were observed at 15°C. Cystzygotes formed at 15°C showed high growth when they were transferred to 25°C conditions, and zoospores matured inside the cells. The production of cyst-zygotes was mostly influenced by temperature, and a gradual increase in temperature was found to be necessary for the formation and growth of cyst-zygotes. The culture conditions facilitating the formation of cyst-zygotes reported in this study can be useful for the production of artificial seeds and breeding technology for the effective cultivation of seaweed.
본 연구는 한국의 개발모형과 국가적 ‘매력’이 의도한 효과성을 달성하 는 데 필요한 조건을 북한의 지역개발 가능성을 중심으로 설명한다. 한 국이 공적개발원조 수혜국에서 공여국으로 전환되면서 영향력이 커지고 있으나, 동시에 점차 확대되고 있는 재정적 지원과 지식원조의 효과성에 관한 우려도 증대되고 있다. 남·북 관계에 관한 담론에서도 개방 후 북한 의 개발과 성장에 대해 개발협력 방식을 통한 한국식 모형 전수를 당연 시하는 논의들이 존재하지만, 잠재적 개발협력 파트너이자 수혜국인 북 한의 관점에서 한국식 모형이 우선순위 및 선호에 부합하고, 매력적일 것인지는 불투명하다. 본 연구는 한국에서 개발도상국으로의 일(一) 방향 의 원조는 국제개발협력 증진과 효과성에 크게 영향을 줄 수 있으며, 오 히려 북한과 같은 개발도상국에서 인식하는 한국의 ‘매력’ 및 선호와 한 국의 정부와 비영리단체가 제공할 수 있는 정책수단과 맞물려야 좋은 성 과를 보일 수 있다는 점을 주장한다. 이를 위해 최근 지속 가능한 개발 목표(SDGs)와 지방의 발전문제에 관심을 보인 북한에 대한 지역개발 논 의를 중심으로 국제개발 효과성 증진을 위한 방향을 제시한다.
Considering the negative impact of IUU fishing on fishery resources and fishery management, a revised approach for estimating risks of the ecosystem-based fisheries assessment (EBFA) of Zhang et al. (2011) was developed that incorporates three components of the IUU (illegal, unreported and unregulated) fishing as penalties. In this study, we introduced ways to develop indicators of IUU fishing suitable for the Korean fishery and apply them to ecosystem-based resource assessment. The indicator for the illegal fishing component was set as the fishing without licenses or permits, and that for the unreported fishing component was set as unreported fishing activities. Indicators for the unregulated fishing component were set as fishing operated by illegal fishing gear, illegal fish capture, fishing operations in prohibited fishing area, and fishing with restrict permits. IUU fishing significantly impacts the stock of target species. Therefore, in this study, the influence of IUU fishing is included in the Species Risk Index (SRI) at the species level, and weights are assigned based on the ratio of the stock, as ․ . The revised ecosystem-based fisheries assessment method, which considers the impact of IUU fishing, was applied to major fisheries on the south coast of Korea. It is necessary to reduce the non-reporting rate through the expansion of the TAC system and improve the accuracy of statistical compilation. To this end, the electronic fishing reporting system, which is being implemented on all vessels in Korean distant water fishing vessels, should be introduced to the coastal and offshore fisheries as well.
강원도 북부의 남북 접경지 3개소(서부-철원, 영서-양구, 영동-고성)에서 2023년 5월 11일부터 10월 12일까지 주요 천공성 해충 분류군인 나무좀아과를 대상으로 시기별 발생 양상 및 4가지 유인제(Ipsenol, Ipsedienol, Alpha-pinene, Monochamol)별 유인되는 종과 개체수를 조사 하였다. 연구결과, 총 26속 45종 7,743개체를 확인하였다. 확인한 종 중, 15종이 모든 조사지역에서 공통적으로 발생하고, 2종(암브로시아나무 좀, 왕녹나무좀)이 모든 조사지에서의 우점종으로 확인되었으며, 4종(오리나무좀, 붉은목나무좀, 여름나무좀, 암브로시아나무좀)이 조사기간(5 월~10월) 중 지속적으로 발생하는 것으로 확인되었다. 지역적으로는 가장 다양한 식물종들로 혼합림을 구성하고 있는 양구지역에서 총 36종 2,840개체가 확인되어 다른 두 조사지에서보다 다양하고 많은 개체가 확인되었다. 각 조사지에서 유인제별 확인한 종수는 유의미한 차이를 보이 지 않았으며 개체수면에서 철원에서는 Monochamol, 양구에서는 Ipsedienol, 고성에서는 Ipsenol 유인제에서 가장 많은 개체가 확인되었다.
The feathery branched green alga Bryopsis plumosa (Hudson) C. Agardh bloomed at Songji Beach, Haenam, Korea, in November 2022. A terrible stench was present on the beach, and the bottom was covered in a thick green mat of green algae. The alga was identified as B. plumosa, which is an opportunistic species currently distributed worldwide. Dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) were analyzed in the bloomed area and compared with those of other vicinities. The DIN and DIP concentrations were 1.067 and 0.461 mg L-1, respectively, which were 6 to 19 times higher than the average concentrations on southwest coasts, including Haenam. The B. plumosa bloom at Songji Beach in November 2022 appears to have depended on DIN and DIP concentrations in seawater. In this study, we report on the mass occurrence of B. plumosa, which appeared for the first time in Korea. This occurrence was found to be closely related to the concentration of nutrients in seawater. Therefore, it is necessary to manage the concentration of nutrients on land flowing into coastal waters to control green algal blooms such as Bryopsis.
This study aimed to examine the morphological characteristics and variation in main traits by comparing the growth of individuals of Ecklonia cava Kjellman (Laminariales, Phaeophyceae) under an aquaculture environment. This survey was conducted from April 2018 to November 2019 at the aquafarm in Jindo-gun, Jeollanam-do (South coast of Korea). To classify the morphology of individuals in the aquaculture farm of E. cava, we investigated fourteen morphological characteristics and calculated four ratios between the measured values. Juvenile individuals showed a simple or oblong lanceolate, and at 3-4 months, a short stipe and holdfast developed, along with a bladelet that developed into the secondary blade form. At 5-7 months, secondary blades were found to develop irregularly on the primary blade. At 8-10 months, the primary blade expanded and secondary blades elongated. At 11-12 months, the secondary blades became oblong. At 13-14 months, the thallus area expanded. At 15-16 months, tertiary blades were formed, the thallus became more complex, the stipe thickened, and the holdfast widened. At 17-18 months, secondary blades clearly developed along with lobes. At 19-20 months, tertiary blades developed and became similar to mature natural blades. In the principal component analysis (PCA), the monthly population of the first year (Q1) and that of the second year (Q2) of the cultured population were divided along PC1, which is related to secondary blade morphological characteristics and the holdfast width. Q2 and natural populations are distributed in descending order of volume in Jeju (J), East Coast (E), and South Coast (S) along PC2, which is related to primary blade and stipe morphological characteristics. The results of this study were judged to offer important criteria for the development of different varieties of E. cava.
In this study, we investigated the microstructure and piezoelectric properties of 0.96(K0.456Na0.536)Nb0.95Sb0.05-0.04 Bi0.5(Na0.82K0.18)0.5ZrO3 (KNNS-BNKZ) ceramics based on one-step and two-step sintering processes. One-step sintering led to significant abnormal grain (AG) growth at temperatures above 1,085 °C. With increasing sintering temperature, piezoelectric and dielectric properties were enhanced, resulting in a high d33 = 506 pC/N for one-step specimen sintered at 1,100 °C (one-step 1,100 °C specimen). However, for one-step 1,115 °C specimen, a slight decrease in d33 was observed, emphasizing the importance of a high tetragonal (T) phase fraction for superior piezoelectric properties. Achieving a relative density above 84 % for samples sintered by the one-step sintering process was challenging. Conversely, two-step sintering significantly improved the relative density of KNNS-BNKZ ceramics up to 96 %, attributed to the control of AG nucleation in the first step and grain growth rate control in the second step. The quantity of AG nucleation was affected by the duration of the first step, determining the final microstructure. Despite having a lower T phase fraction than that of the one-step 1,100 °C specimen, the two-step specimen exhibited higher piezoelectric coefficients (d33 = 574 pC/N and kp = 0.5) than those of the one-step 1,100 °C specimen due to its higher relative density. Performance evaluation of magnetoelectric composite devices composed of one-step and twostep specimens showed that despite having a higher g33, the magnetoelectric composite with the one-step 1,100 °C specimen exhibited the lowest magnetoelectric voltage coefficient, due to its lowest kp. This study highlights the essential role of phase fraction and relative density in enhancing the performance of piezoelectric materials and devices, showcasing the effectiveness of the two-step sintering process for controlling the microstructure of ceramic materials containing volatile elements.
In order to present a predictive drift model, Jeju National University's training ship was tested for about 11 hours and 40 minutes, and 81 samples that selected one of the entire samples at ten-minute intervals were subjected to regression analysis after verifying outliers and influence points. In the outlier and influence point analysis, although there is a part where the wind direction exceeds 1 in the DFBETAS (difference in Betas) value, the CV (cumulative variable) value is 6%, close to 1. Therefore, it was judged that there would be no problem in conducting multiple regression analyses on samples. The standard regression coefficient showed how much current and wind affect the dependent variable. It showed that current speed and direction were the most important variables for drift speed and direction, with values of 47.1% and 58.1%, respectively. The analysis showed that the statistical values indicated the fit of the model at the significance level of 0.05 for multiple regression analysis. The multiple correlation coefficients indicating the degree of influence on the dependent variable were 83.2% and 89.0%, respectively. The determination of coefficients were 69.3% and 79.3%, and the adjusted determination of coefficients were 67.6% and 78.3%, respectively. In this study, a more quantitative prediction model will be presented because it is performed after identifying outliers and influence points of sample data before multiple regression analysis. Therefore, many studies will be active in the future by combining them.
Piezoelectric technology, which converts mechanical energy into electrical energy, has recently attracted drawn considerable attention in the industry. Among the many kinds of piezoelectric materials, BaTiO3 nanotube arrays, which have outstanding uniformity and anisotropic orientation compared to nanowire-based arrays, can be fabricated using a simple synthesis process. In this study, we developed a flexible piezoelectric energy harvester (f-PEH) based on a composite film with PVDF-coated BaTiO3 nanotube arrays through sequential anodization and hydrothermal synthesis processes. The f-PEH fabricated using the piezoelectric composite film exhibited excellent piezoelectric performance and high flexibility compared to the previously reported BaTiO3 nanotube array-based energy harvester. These results demonstrate the possibility for widely application with high performance by our advanced f-PEH technique based on BaTiO3 nanotube arrays.
호산구성 장염에 의한 급성 췌장염은 매우 드문 질환으로 증상 및 검사실 소견이 특별하지 않아 진단이 어렵다. 급성 췌장염의 원인이 명확하지 않은 경우, 가능한 원인으로 매우 드물지만 호산구성 위장염이 있을 수 있으며, 본 저자들은 호산구성 위십이지장염에 의해 발생한 재발성 급성 췌장염을 진단하고 류코트리엔 수용체 길항제로 치료하였던 증례를 문헌고찰과 함께 보고한다.
2013년부터 시작된 선진국의 양적완화 정책은 신흥국을 포함한 전세계 경제에 많은 영향을 주었다. 양적완화 외에도 전세계는 미․중 패권전쟁, 러-우전쟁, COVID-19 등 충격을 겪으면서 경제․경영환경에도 급격한 변화 를 겪게 된다. 따라서 지난 10년간 보고된 글로벌 재무 관련 연구를 포괄적으로 리뷰하면서 시사점 찾을 필요가 있다. 이를 위해 본 연구는 2013-2022년 국제경영연구 및 국제경영리뷰에 게재된 글로벌 재무 분야 논문에 대 해 메타분석 및 문헌연구를 통해 연구동향을 심층적으로 고찰하였다. 지난 10년 동안 발표된 국제경영연구 및 국 제경영리뷰의 총 605편 논문 중 전략 253편, 글로벌 재무 124편, 글로벌 마케팅 95편, 글로벌 인사조직 77편, 해외직접투자 33편, 지역 6편, 기타 17편으로 구성되었다. 이 중 글로벌 재무 관련 논문은 20.5%를 차지하였고, 게재편수는 증가하였다. 글로벌 재무 분야의 논문은 기업재무 관련 논문 55편(44.4%), 국제금융시장 관련 44편 (35.5%), 위험관리 관련 25편(20.2%)으로 분류할 수 있다. 기업재무 관련 논문 중에서도 ‘외국인투자자 및 기 업지배구조’에 대한 논문이 36편(29.0%)으로 가장 많이 발표되어, 외국인투자자의 영향력과 기업지배구조 이슈 에 대한 관심이 높음을 알 수 있다. 글로벌 재무 분야는 다양한 연구주제가 활발히 이루어지고 있으며, 확장되고 있는 추세이다. 본 연구는 글로벌 재무의 연구동향을 파악하고 연구자들에게 향후 연구의 방향과 새로운 아이디 어를 제시하는 데 도움을 줄 것으로 사료된다.
Thermoelectric (TE) energy harvesting, which converts available thermal resources into electrical energy, is attracting significant attention, as it facilitates wireless and self-powered electronics. Recently, as demand for portable/wearable electronic devices and sensors increases, organic-inorganic TE films with polymeric matrix are being studied to realize flexible thermoelectric energy harvesters (f-TEHs). Here, we developed flexible organic-inorganic TE films with p-type Bi0.5Sb1.5Te3 powder and polymeric matrices such as poly(3,4-eethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and poly (vinylidene fluoride) (PVDF). The fabricated TE films with a PEDOT:PSS matrix and 1 wt% of multi-walled carbon nanotube (MWCNT) exhibited a power factor value of 3.96 μW ‧ m-1 ‧ K-2 which is about 2.8 times higher than that of PVDF-based TE film. We also fabricated f-TEHs using both types of TE films and investigated the TE output performance. The f-TEH made of PEDOT:PSS-based TE films harvested the maximum load voltage of 3.4 mV, with a load current of 17.4 μA, and output power of 15.7 nW at a temperature difference of 25 K, whereas the f-TEH with PVDF-based TE films generated values of 0.6 mV, 3.3 μA, and 0.54 nW. This study will broaden the fields of the research on methods to improve TE efficiency and the development of flexible organic-inorganic TE films and f-TEH.