한국 남해 나로도와 소리도 사이 해역의 1998년 하계 해황 및 적조소멸과의 관계

최현용,Choi, Hyun-Yong 한국해양학회 2001 바다 Vol.6 No.2

Cochlodinium polykrikoides 유해성적조 발생지역인 한국 남해 나로도와 소리도 사이 해역의 물리적인 환경을 연구하기 위하여 1998년 5월31일부터 9월 24일까지 7회에 걸쳐 수온 및 염분을 관측하였다. 연구해역의 표층에서 30m깊이까지의 수층에서는 관측 초기인 춘계부터 하계로 갈수록 수온이 증가하고 염분은 낮아지는 물성의 계절적인 변화가 뚜렷하였는데 수층전체의 평균수온은 총 조사기간동안 $6^{\circ}C$ 증가하고 평균염분은 2.71 psu 낮아졌다. 관측된 평균염분의 변화는 연구해역의 강수와 인접육지에 의해 공급될 수 있는 담수량만으로는 설명할 수 없었으며, 남해외해역으로부터 유입되는 저염수에 의해 일어났을 것으로 해석되었다. 이 해역에서 적조의 발생시기, 진행시기 및 적조가 사라진 시기에 염분의 공간적인 분포가 다른 특징을 보였으며, 특히 적조가 사라진 시기에는 염분이 직전 시기에 비해 크게 낮아지고 수층구조도 직전시기의 성층구조에서 혼합층구조로 변화하였는데, 이와 같은 변화는 남해 외해역으로부터 저염수의 유입으로만 설명할 수 있었다. 이로부터 물리적인 해수유동이 이 해역에서 적조가사라진 주요한 원인의 하나로 제시되었다. 본 연구결과는 차후 남해 연안역의 적조현상을 이해하기 위해서는 인접 육지로부터 유입되는 환경적 요소들은 물론 대상해역을 포함한 남해 외해역의 해수순환특성, 그리고 해수순환에 의해 이송되는 해수의 물리, 화학 및 생물학적 요소를 종합적으로 연구해야할 필요성을 시사한다. Hydrographic surveys were carried out seven times during May 31, 1998 and September 24, 1998 in order to study the physical environments of the coastal area between Narodo Is. and Sorido Is. in the southern sea of Korea (the South Sea) where the occurrence of Cochlodinium polykrikoides red tide is frequently observed in summer. Temperature and salinity of the water column from the surface to the depth of 30 m exhibit large seasonal variations. Mean temperature of the water column increased by 6 and mean salinity of the water column decreased by 2.71 psu during the observation period. Both the freshwater supplied from the adjacent land and the precipitation over the study area cannot account for the observed salinity variations. The influx of the low salinity water from the offshore area is considered to be the main cause for the observed salinity changes. Surface salinity in the study area shows different spatial distribution in the period of outbreaking, mid-stage and disappearance of the red tide. Especially, salinity was abruptly lowered at the stage of disappearance of red tide as compared to salinity of the previous observation period. Vertical structure of water properties also became vertically homogeneous at the disappearance stage, while it was highly stratified in the previous observation. Such changes can only be explained by the inflow of low salinity water from the offshore, which is considered as the most possible cause for the disappearance of the red tide in the study area. This study suggests that exchanges of water, and chemical and biological factors between coastal areas and of shore area in the South Sea need to be studied in association with the general circulation of the South Sea in order for the better understanding of the occurrence and disappearance of the red tide in the coastal area of the South Sea.

금강하구언 대량방류시 황해 중동부 해역의 염분분포

최현용,이상호,유광우,Choi, Hyun-Yong,Lee, Sang-Ho,You, Kwang-Woo 한국해양학회 1999 바다 Vol.4 No.1

금강에서 유출된 담수의 거동 특성을 파악하기 위해, 금강하구에서 담수가 대량 방류된 1997년 7월 7일에서 7월 12일 사이에 한국 서해 중부의 금강하구에서 태안 반도에 이르는 해역에서 해양조사를 실시하였다. 금강하구에서 북서쪽으로 약 60 km 떨어진 어청도 사이의 해역은 30.0 psu 이하의 저염수가 분포하였으며, 어청도 이북해역에서도 부분적으로 금강 담수 기원으로 해석되는 저염수가 관측되었다. 특히 금강 담수 플룸에 의한 것으로 추정되는 염분전선이 십이동파도 인근에서 관측되었으며, 48 시간 후에는 북서쪽으로 약 25 km 떨어진 어청도 근방에서도 관측되어 염분전선의 위치가 시간에 따라 이동하는 결과를 보였다. 담수 플룸에 의해 수직성층이 잘 된 십이동파도 북측해역에서 20 시간 연속 관측된 조류를 분석한 결과 담수 플룸 내인 상층에서 평균유속이 0.2 m/s 이상인 북서방향의 흐름이 관측되었다. 관측된 평균흐름 및 염분전선의 위치변동은 금강 담수 플룸이 외해로 확장되는 과정으로 해석되며, 금강하구에서 유출되는 담수가 금강하구 인근 연안역의 표층해수 순환에 크게 영향을 줄 수 있음을 제시한다. Hydrographic survey was carried out in the mid-eastern Yellow Sea from Keum River to Taean Peninsula in order to study the motion of the freshwater from the Keum River during July 07-12, 1997 when a large volume of freshwater was discharged from the Keum River weir. The low-salinity (less than 30.0 psu) plume was distributed over the large area between the Keum River and Ochong Island, 60 km northwest off the Keum River mouth. A band of relatively low saline water, originating from the Keum River, was also observed to the north of Ochong Island. The strong haline front had advanced from near Sibidongpa Island to Ochong Island, 25 km northwest of Sibidongpa Island, for 48 hours. A northwestward flow of a speed greater than 0.2 m/s was observed in the surface plume layer to the north of Sibidongpa Island where the water column was strongly stratified. The observed mean flow and the change of the frontal position are interpreted as resulting from the spreading of the Keum River plume. These results suggest that the discharge from the Keum River plays an important role in the coastal circulation of the mid-eastern Yellow Sea adjacent to the river.

A Monte Carlo Study of the Diffusion Process of Thomson-Scattered Line Radiation in Phase Space

최현용,이희원 한국천문학회 2023 Journal of The Korean Astronomical Society Vol.56 No.1

We investigate the diffusion process of Thomson-scattered line photons in both real space and frequency space through a Monte Carlo approach. The emission source is assumed to be monochromatic and point-like embedded at the center of a free electron region in the form of a sphere and a slab. In the case of a spherical region, the line profiles emergent at a location of Thomson optical depth $\tau_{\rm Th}$ from the source exhibit the full width of the half maximum $\sigma_\lambda \simeq \tau_{\rm Th}^{1.5}$. In the slab case, we focus on the polarization behavior where the polarization direction flips from the normal direction of the slab to the parallel as the slab optical depth $\tau_{\rm Th}$ increases from $\tau_{\rm Th} \ll 1$ to $\tau_{\rm Th} \gg 1$. We propose that the polarization flip to the parallel direction to the slab surface in optically thick slabs is attributed to the robustness of the Stokes parameter $Q$ along the vertical axis with respect to the observer's line of sight whereas randomization dominates the remaining region as $\tau_{\rm Th}$ increases. A brief discussion on the importance of our study is presented.

자기주도적 학습능력에 따른 영자신문 제작 활동이 고등학교 학습자의 영어 쓰기 능력 및 학습 동기에 미치는 영향: 3년 종단 연구

최현용,김수연 한국중등영어교육학회 2020 중등영어교육 Vol.13 No.4

This study aims to explore the effects of English newspaper making activity on Korean high school learners’ English writing skills and learning motivation according to their self-directed learning ability. Twelve first year high school students, who joined the English newspaper making activity, participated in three-year longitudinal study from mid-March 2017 to December 2019. The results of this study are as follows. First, the higher the self-directed learning ability, the higher improvement in the English writing skills. Second, both the self-directed learning ability upper group and the lower group showed improvement in most of the 10 measures that showed the degree of development of syntactic complexity. Finally, the higher the self-directed learning ability, the higher improvement in learning motivation. The findings of this study provide some useful pedagogical implications for teachers to understand learners better at future English education fields and balanced learning environment.

라이다 센서 기술 및 산업동향

최현용,Choe, Hyeon-Yong 대한전기학회 2017 전기의 세계 Vol.66 No.9

Learners’ Perceptions and Needs Analysis of Global Citizenship Education: Focused on Korea High School English Education

최현용,강문구,조운겸 한국영어어문교육학회 2022 영어어문교육 Vol.28 No.3

This study aims to identify the learners’ perceptions and needs analysis for Global Citizenship Education (GCED) in high school English education. To achieve the purpose of the study, an online survey was conducted on 369 students attending 10 general high schools across the country. First, most respondents shared the value and necessity of GCED as an education, but practical education related to GCED was rarely dealt with in the school fields. Also, it was very limited in the case of the school level or the subject where GCED was practiced, and in particular, the response to the high school English education could not be confirmed. Second, most students expected their needs to be reflected in the composition of the high school English curriculum and the production of English textbooks. In addition, there was a clear desire from students to reflect GCED-related contents and materials in the composition of the high school English curriculum and English textbook production. These results will not only help teachers and educators to understand how much high school learners are aware of GCED in English education and what they require but also suggest the direction of the high school English curriculum operation.

A Case of Intracranial Mycotic Aneurysm due to Aspergillus species.

최현용,임용철,강재규 대한뇌혈관외과학회 2010 Journal of Cerebrovascular and Endovascular Neuros Vol.12 No.3

Intracranial mycotic aneurysms due to Aspergillus species are extremely uncommon but fatal. A medium-sized ruptured intracranial aneurysm at the middle cerebral artery bifurcation was identified in a 50-year-old female patient. Proper microsurgical clipping was not feasible due to the aneurysm? friable nature. Microsuture and wrapping were done instead. Histological findings confirmed a mycotic aneurysm caused by Aspergillus. Herein, we report on the clinical course and histopathological findings with a relevant literature review. (Kor J Cerebrovascular Surgery 12(3):123-125, 2010)

황해 중부 연안 수온전선역의 정량적 해석

최현용,이상호,오임상,Choi, Hyun-Yong,Lee, Sang-Ho,Oh, Im-Sang 한국해양학회 1998 바다 Vol.3 No.1

하계에 연안혼합역과 외해성층역 사이에서 강력한 표층수온전선이 형성되는 한국 서해 중부의 태안반도 인근해역에서 1994년 7월, 1995년 5원 및 1996년 6월 등 3회에 걸쳐 취득한 해수물성자료를 분석하였다. 수직혼합역은 최저 15 m에서 최고 60 m 이상까지의 다양한 수심의 지형으로 이루어졌으며, 수심에 관계없이 표층과 저층의 수온차가 $1^{\circ}C$ 이내였다. 관측시기에 관계없이 혼합역 내의 수평적인 표층수온차는 작으면서도 수심에 반비례하는 특정을 보이고 표층수온이 가장 낮은 해역은 태안반도 서단에서 남서방향으로 형성되어있는 수심이 50 m 이상인 깊은 수로를 중심으로 관측되었다. 또한 6월에 관측한 표층수온전선이 태양복사열이 더 강한 7월에 관측한 표층수온전선에 비해 더 강한 특성을 보였다. 이러한 관측결과는 연구해역의 표층수온전선역은 수층의 수직혼합에 의해 형성되지만, 수온전선의 강도는 수직혼합역의 수성 및 외해성층역의 수온의 수직구조 등에 의해 결정되는 것으로 해석된다. The hydrographic data collected at three different times July, 1994, May, 1995 and June, 1996 around Taean peninsula in the mid-Yellow Sea off Korea, well known for the well-defined surface thermal fronts in summer, were analyzed. In the vertically well-mixed area where water depths varied from 15 m depth to 60 m depth, the temperature difference in the water column was less than $1^{\circ}C$. The temperature observed in the vertically well-mixed area was reversely related with the water depths and the coldest surface water was always observed over the deep channel with the depth of more than 50m, which developed southwestward off the promontory of Taean peninsula, irrespective of the observation period. The strengths of surface thermal front observed in June were much stronger than those in July, even though the surface temperature of stratified area were nearly the same as in July. These observed features could be explained as follows: A major physical process for the formation of the surface thermal front is the vertical mixing of water column but the detailed thermal structure in the study area depend on the physical parameters such as the water depth in the vertically well-mixed side and the vertical thermal structure in the stratified side.

하구언 수문 작동으로 인한 금강 하구역의 물리적 환경변화: III. 저염수의 조석동조

최현용,권효근,이상호,Choi, Hyun-Yong,Kwon, Hyo-Keun,Lee, Sang-Ho 한국해양학회 2001 바다 Vol.6 No.3

금강하구언에서 낙조동안 인위적으로 방류된 담수의 하구 내 거동을 파악하고자 1997년 5월과 1998년 7월에 각각 수로방향으로 설정된 3개 지점에서 표층 염분변화를 관측하였으며, 1999년 7월에는 군산-장항간 도선항로를 따라 18일간 표층염분과 수온을 관측하였다. 관측된 염분변화의 특징으로부터 방류된 담수가 하구 내에서 거동${\cdot}$소멸하는 과정을 분석하였다. 담수가 방류되면 저염수는 하구 폭 전반에 걸친 강한 염분전선을 형성하며 담수거동은 기본적으로 조석운동에 동조되어 수로를 따라 왕래하고, 이 전선의 통과로 염분은 급격한 변화를 보인다. 수문개폐로부터 한 조석주기 이후의 하구 폭 평균염분의 시간적 변화로부터 해석된 수로방향의 공간적 분포는 전선역에 담수희석수가 응축되며 표층염분이 상류쪽으로 갈수록 점진적으로 증가하는 것으로 제시되었다. 이러한 염분의 전선역 분포는 두 시간정도의 하구언 수문 개방에 의한 급작스런 담수공급과 중단에 의해 발생한 것으로 해석되었다. 매일 담수방류의 반복은 수문 개방시기에 의해 이전의전선과 새로운 전선의 분리(이중전선) 혹은 병합을 만들고, 담수공급이 2일 이상 중단되면 염분이 증가되며 전선이 소멸한다. 또한, 표층염분 변화에 나타나는 변동과 변이는 하구언에서 인위적으로 행해지는 담수 방류량 차이에 의해 발생하는 염분전선의 세기와 통과시기의 공간적 차이, 그리고 일시적인 하구수로 방향을 따른 염분전선 등에 의한 것으로 해석되었다. To examine the movement of the freshwater discharged artificially into the estuary during ebbing period in the Keum River dike we observed surface salinity variations in three stations along the estuary channel in May 1998 and July 1997 and surface temperature and salinity along the ferry-route between Kunsan and Changhang during eighteen days in July 1999. Based upon the typical features of observed salinity variation, we analyzed the excursion and decay processes of the discharged water. When freshwater is discharged, the low-salinity water forms strong salinity front over the entire estuary width, which basically moves forth and back by tidal modulation along the channel, producing the sudden change of surface salinity with the front passage. Salinity distribution along the channel, which is deduced from time variation of mean salinity over the estuary width, after one tidal period from gate operation suggests that diluted low-salinity water is trapped to the front and surface salinity increases gradually toward the upstream region. This frontal distribution of salinity is interpreted to be produced by the sudden gate operation supplying and stopping of freshwater within about two hours. Daily repeat of freshwater discharge produces separation (double front) or merge between decaying and new-generated fronts depending on dike-gate opening time, and the front decays with salinity increasing if the freshwater supply is stopped more than two days. In addition, the observed fluctuations and deviations in surface salinity variation is explained in terms of the differences of fronts intensity, their transition time and temporal salinity front running along the channel, which can be generated due to artificial gate-operation for the discharging time and water volume in the estuary dike.

니콜라이 레스코프의 《푸갈로(Пугало)》

최현용 한국노어노문학회 2003 한국노어노문학회 학술대회 발표집 Vol.2003 No.11