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.

1990년대 이후 한국경제에서 경제 서비스화와 학력별 임금격차 확대 현상이 나타났다. 이런 상황에 서 학력별 노동수요의 결정요인분석을 위해 먼저 인적자본론을 바탕으로 노동을 고학력노동과 저학력노 동으로 분리하였다. 생산함수는 콥-다글라스 함수로 가정하고 생산요소는 물적자본(K), 저학력노동( ) 과 고학력노동( )으로 하였다. 이것을 바탕으로 외생변수로 기술진보(t), 산출량(Q)과 세계화()를 상 정한 학력별 노동수요함수를 도출하였다. 이것을 바탕으로 로그선형회귀모형을 설정하고 한국의 주요 3 개 산업(제조업, 건설업, 금융업)의 학력별 노동수요에 영향을 미치는 요인을 비교분석하였다. 주요 3개 산업의 학력별 노동수요 결정요인을 비교분석한 결과 다음과 같은 공통점과 차이점을 발견하였다. 첫째, 학력별 노동수요는 생산요소 상대가격보다는 생산량, 기술변화와 세계화 등 외생적 요인의 영향을 받아 고학력노동수요 중심의 노동시장구조로 변화하고 있다. 특히 학력별 노동의 상대임금이 학 력별 노동수요에 유의미한 영향이 없을 정도로 학력별 노동시장은 분절되어 있다. 둘째, 생산량 증가(감 소)는 건설업의 고학력노동과 저학력노동수요에 가장 큰 고용증가(구축)효과를 가져왔다. 따라서 건설업 이 경기변동에 가장 민감한 산업임을 알 수 있다. 기술진보는 제조업의 저학력노동에 가장 큰 고용구축효 과를, 금융업의 고학력노동에 고용증가효과를 가져왔다. 셋째, 세계화는 제조업에서 저학력노동과 고학력 노동의 고용증가효과를, 금융업에서는 고학력노동의 고용증가효과를 가져왔지만 건설업에서는 학력별 노동수요에 유의미한 영향을 미치지 못했다. 이런 연구 결과를 바탕으로 한국 주요 산업의 고용에 대해 다음과 같은 시사점을 제공한다. 첫째, 요소 상대가격 변화를 통한 정부정책이나 기업전략은 학력별 노동수요에 대한 영향이 미미하여 제한적일 수밖 에 없다. 둘째, 기술진보로 인해 제조업에서는 저학력노동의 고용구축효과에 따른 기업의 노무관리가 필 요하다. 반면 금융업에서는 기술진보와 세계화로 인한 고학력노동의 고용증가효과에 대비하기 위해 기업 차원에서는 기존노동의 교육과 훈련 프로그램이, 정부차원에서는 인재양성정책이 필요하다. 셋째, 건설업 은 경기에 민감하기 때문에 경기호불황에 대비하기 위한 기업의 고용안정전략이 필요하다.

Korean tuna purse seine fishery in the Western and Central Pacific Ocean (WCPO) began to operate in earnest in the early 1980s. Since then, the total catch has shown an increasing trend and the target species are skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacare) and bigeye tuna (Thunnus obesus). Based on the operational data of Korean tuna purse seine fishery from 2016 to 2020, the catch rates of target species (skipjack and yellowfin tunas) were analyzed by operation time for set types (free school and FAD sets). In the case of the free school sets, they were usually made from sunrise to sunset, and the catch rate was high before and after sunrise for skipjack tuna and before sunset for yellowfin tuna. On the other hand, for the FAD sets, more than 90% of them were made just before sunrise, and there were few operations during the daytime. The purpose of this study is to examine whether there are differences in the catch rate of skipjack and yellowfin tunas by operation time and by school type for Korean tuna purse seine fishery in the WCPO, which could be helpful in understanding its fishing characteristics and providing useful information for developing the stock indices of the target species.

Among the fishing vessels operating in the coastal waters, jigging fishing vessels were considered representative vessels engaged only by wind, sea, tide, and external force. Then, a fishing vessel with a length of shorter than 10 m from July 1, 2018 to August 5, 2019 was studied to obtain a drift prediction model by multiple regression analysis. In the correlation analysis between variables for leeway of speed and direction, the speed and direction of tidal seem to be the most affected in coastal waters. Therefore, it should be considered an explanatory variable when conducting drift tests. As a result of multiple regression analysis on the predicted equations of leeway speed and direction due to the external force on the drift of the fishing vessel, p < 0.000 was considered significant in the F-test, but the coefficient of determination was 55.2% and 37.8%. The effect on the predicted leeway speed was in the order of the tidal speed and current speed. In addition, the impact on the predicted leeway direction was in the order of the tidal speed and current speed.

In this study, Y3Al5O12:Eu3+ red phosphors were synthesized at different temperatures using a solid state reaction method. The crystal structures, surface and optical properties of the Y3Al5O12:Eu3+ red phosphors were investigated using Xray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and photoluminescence (PL) analyses. From XRD results, the crystal structure of the Y3Al5O12:Eu3+ red phosphors was determined to be cubic. The maximum emission spectra were observed for the Y3Al5O12:Eu3+ red phosphor prepared by annealing for 4h at 1,700 oC. The 565~590 nm photoluminescent spectra of the Y3Al5O12:Eu3+ red phosphors is associated with the 5D0 → 7F2 magnetic dipole transition of the Eu3+ ions. The intensity of the photoluminescent spectra in the red phosphors is more dominant for the magnetic dipole transition than the electric dipole transition with increasing annealing temperature. The International Commission on Illumination (CIE) coordinates of Y3Al5O12:Eu3+ red phosphors prepared by 1,700 oC annealing temperature are X = 0.5994, Y = 0.3647.

본 연구에서는 국립공원에서 자연의 소리는 생태계의 구성요소임과 동시에 탐방객들이 공원을 체험하는 중요한 요소이다. 따라서 국립공원 내 소음 분포 특성을 파악하고 자연의 음환경(Soundscape) 보존 및 복원을 위한 노력은 국립공원 관리 차원에서 중요한 과제 중 하나이다. 그러나 여전히 국내 국립공원에서는 소음 관리 및 음환경 보존에 대한 관심이 미약한 것이 사실이다. 무등산국립공원은 호남지역에서 가장 중요한 자연보호지역 중 하나로 계절별 동물이 우는 소리, 물소리, 바람 소리 등 탐방객들에게 자연의 소리를 제공할 수 있는 최적의 장소이지만 대도시에 인접해 있고 공원 내부로 도로 및 대규모 시설지가 인접해있는 등 소음이 발생하여 공원 내 음환경에 위협이 되고 있는 상황이다. 따라서 본 연구는 소음지도, 탐방로 소리등급도, 주요 지점의 음환경 녹음 데이터, 소리자원 분포도 등의 분석을 통해 무등산국립공원 내 소리 분포 특성을 파악하고 광범위한 소음의 영향을 나타냄으로써 음환경 관리의 필요성을 시사하고 있다는 중요성을 지니고 있다. 반면 본 연구에서는 연구 인력과 장비의 한계로 인하여 소음지도, 탐방로 소리등급도, 소리자원 분포도의 속성 데이터 수집 기간이 상이한 점이 한계점으로 남는다. 그러나 본 연구의 결과는 탐방 만족도 및 자연의 음환경 보존 등을 목표로 향후 지속적인 음환경 보존 및 관리를 위해 활용될 수 있는 기초자료가 될 것으로 판단된다.