Who should undergo extensive diagnostic workups in patients with presumed lacunar stroke?

여승현 대한뇌졸중학회 2005 Journal of stroke Vol.7 No.1

B a c k g ro u n d : The upper limit for the size of a lacuna has been established at a diameter of 15 mm. We aimed toassess infarct size and develop a model for predicting whether a deep infarct is caused by small arterial occlusion.M e t h o d s : We prospectively studied 304 patients with acute, symptomatic, subcortical infarcts. All the patientsshowed relevant lesions within the striatocapsular territory on diffusion-weighted imaging, and those with concomitantcortical lesions were excluded from this study. We divided the patients into two groups: (a) those with neitherocclusion of the relevant vessels nor potential sources of cardioembolism (cryptogenic group, n=206), (b) patientswith large artery atherosclerosis, cardioembolism or other documented etiology (non-lacunar group, n=98). Weused Receiver Operating Characteristic (ROC) curves to validate the models in predicting non-lacunar mechanisms.R e s u l t s : The sex ratio and risk factor profile did not differ between the groups. Lacunar syndromes were more frequentlyfound in the cryptogenic group (85.4%) than in the non-lacunar group (57.1%) (P〈0.001). The larg e s tdiameter in patients in the cryptogenic group (14.5±6.8 mm) was smaller than that in patients with other documentedetiologies (20.0±11.4 mm) (P〈0.001). Discrimination was better when both infarct size and syndromewere considered than when infarct size alone was considered (P=0.031) ; the area under the ROC curve was 0.644for the latter and 0.700 for the former. In calculating the non-lacunar mechanisms risk index score, the valueassigned was one point for each millimeter infarct size, and 17 points for the presence of non-lacunar syndrome. Ascore of ≥21 points forecast a high probability of non-lacunar mechanisms, yielding a sensitivity of 61% (95% CI,51-71%) and specificity of 75% (95% CI, 68-81%); positive and negative predictive values were 54% and 80%,r e s p e c t i v e l y. C o n c l u s i o n s : A clinically significant proportion of clinicoradiologic lacunae may be associated withunderlying non-lacunar mechanisms. Decisions regarding the extent of diagnostic procedures in patients with subcorticalinfarcts may be guided by the point value in terms of the stroke syndrome and infarct size.(Korean Journal of Stroke 2005;7(2): 133~143)

Elementary Preservice Teachers’ Noticing and Evaluation of Digital Mathematical Resources

여승현 한국수학교육학회 2023 수학교육연구 Vol.26 No.2

With the rapid advancement of educational technology, recent studies have connected teachers’ professional noticing with the use of digital resources in mathematical instructions. In this study, I examined elementary mathematics preservice teachers’ attending and interpreting a mathematical software, ST Math, in the exploring and implementing phases. The findings indicate that preservice teachers paid attention to visual representations and manipulation prior to interactions with children and further took into consideration on task structures and situated context after interactions. They interpreted the events based on connected mathematical knowledge of prior interactions and further reflected on the progression of problem-solving strategies and sequence of tasks. In addition, four distinctive profiles of transitioning of evaluation on ST Math activities were identified with illustrations. Implications for noticing and teacher education were discussed.

문제제기 및 해결을 통한 한국과 미국 예비교사의 분수 곱셈 이해 탐색

여승현,이지영 한국수학교육학회 2022 수학교육 Vol.61 No.1

Mathematics teachers’ content knowledge is an important asset for effective teaching. To enhance this asset, teacher’s knowledge is required to be diagnosed and developed. In this study, we employed problem-posing and problem-solving tasks to diagnose preservice teachers’ understanding of fraction multiplication. We recruited 41 elementary preservice teachers who were taking elementary mathematics methods courses in Korea and the United States and gave the tasks in their final exam. The collected data was analyzed in terms of interpreting, understanding, model, and representing of fraction multiplication. The results of the study show that preservice teachers tended to interpret (fraction)×(fraction) more correctly than (whole number)×(fraction). Especially, all US preservice teachers reversed the meanings of the fraction multiplier as well as the whole number multiplicand. In addition, preservice teachers frequently used ‘part of part’ for posing problems and solving posed problems for (fraction)×(fraction) problems. While preservice teachers preferred to a area model to solve (fraction)×(fraction) problems, many Korean preservice teachers selected a length model for (whole number)×(fraction). Lastly, preservice teachers showed their ability to make a conceptual connection between their models and the process of fraction multiplication. This study provided specific implications for preservice teacher education in relation to the meaning of fraction multiplication, visual representations, and the purposes of using representations. 본 연구에서는 한국과 미국의 초등예비교사들의 분수 곱셈에 대한 이해를 살펴보기 위해서 문제제기 및 문제해결 과제의 수행 결과를 분석하였다. 연구 결과, 첫째, (분수)×(분수)의 상황에 비해서 (자연수)×(분수)에서 피승수와 승수의 위치를 혼동하여 승수를 분수가 아닌 자연수로 생각하는경향이 더 많이 나타났다. 둘째, (분수)×(분수)에서는 집합이나 길이에 비해서 넓이 모델을 선호하는 것으로 나타났고, 대부분의 예비교사들이주어진 수식의 계산과정이 나타나도록 모델을 연결하여 설명하였다. 이를 바탕으로 예비교사의 곱셈의미 이해에 대한 연구의 시사점을 제언하였다.

Development of Mathematical Task Analytic Framework: Proactive and Reactive Features

여승현,김정연,권나영,조호윤,김진호,임웅 한국수학교육학회 2022 수학교육연구 Vol.25 No.4

A large body of previous studies investigated mathematical tasks by analyzing the design process prior to lessons or textbooks. While researchers have revealed the significant roles of mathematical tasks within written curricular, there has been a call for studies about how mathematical tasks are implemented or what is experienced and learned by students as enacted curriculum. This article proposes a mathematical task analytic framework based on a holistic definition of tasks encompassing both written tasks and the process of task enactment. We synthesized the features of the mathematical tasks and developed a task analytic framework with multiple dimensions: breadth, depth, bridging, openness, and interaction. We also applied the scoring rubric to analyze three multiplication tasks to illustrate the framework by its five dimensions. We illustrate how a series of tasks are analyzed through the framework when students are engaged in multiplicative thinking. The framework can provide important information about the qualities of planned tasks for mathematics instruction (proactive) and the qualities of implemented tasks during instruction (reactive). This framework will be beneficial for curriculum designers to design rich tasks with more careful consideration of how each feature of the tasks would be attained and for teachers to transform mathematical tasks with the provision of meaningful learning activities into implementation.

파킨슨병과 다계통 위축증 환자들에서 후각기능 및 후각기능과 심장 123I-MIBG섭취율과의 연관성

여승현,신동훈,김현준,이필류 대한신경과학회 2007 대한신경과학회지 Vol.25 No.1

Semiotic mediation through technology: The case of fraction reasoning

여승현 한국수학교육학회 2021 수학교육 Vol.60 No.1

This study investigates students’ conceptions of fractions from a measurement approach while providing a technological environment designed to support students’ understanding of the relationships between quantities and adjustable units. 13 third-graders participated in this study and they were involved in a series of measurement tasks through task-based interviews. The tasks were devised to investigate the relationship between units and quantity through manipulations. Screencasting videos were collected including verbal explanations and manipulations. Drawing upon the theory of semiotic mediation, students’ constructed concepts during interviews were coded as mathematical words and visual mediators to identify conceptual profiles using a fine-grained analysis. Two students changed their strategies to solve the tasks were selected as a representative case of the two profiles: from guessing to recursive partitioning; from using random units to making a relation to the given unit. Dragging mathematical objects plays a critical role to mediate and formulate fraction understandings such as unitizing and partitioning. In addition, static and dynamic representations influence the development of unit concepts in measurement situations. The findings will contribute to the field’s understanding of how students come to understand the concept of fraction as measure and the role of technology, which result in a theory-driven, empirically-tested set of tasks that can be used to introduce fractions as an alternative way.

손목굴증후군 환자의 신경생리학적 소견과 혈청 지질 수치와의 상관관계

여승현,김동훈,손성연,홍윤희,박재범,주인수 대한임상신경생리학회 2010 Annals of Clinical Neurophysiology Vol.12 No.2

Background: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy caused by compression of the median nerve beneath the transverse carpal ligament. CTS can be correctly diagnosed by the patients' description of symptoms and electrophysiological tests that measure nerve conduction through the wrist. Many previous studies reported various risk factors of CTS, such as obesity, diabetes mellitus, thyroid disease and trauma. Obesity is associated with both hyperlipidemia and CTS. This study focused on the relationship between severity of CTS and serum lipid level. Methods: One hundred fourteen patients with CTS and 74 controls were divided into four groups according to the severity; normal, mild,moderate and severe. And then serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C) and high-density lipoprotein (HDL-C) were measured in each group. Results: There was a positive correlation between TG and CTS severity (p<0.001). But TC, LDL-C and HDL-C were not correlated with CTS severity. Conclusions: These results suggest that high serum TG may act as an aggravating factor of CTS.

Mathematics classrooms that students love, grade 1: Numbers and operations by Jinho Kim (2023)

여승현 한국수학교육학회 2024 수학교육연구 Vol.27 No.1

Mathematics Classrooms that Students Love, Grade 1: Numbers and Operations is a book that reviews student-centered educational strategies in mathematics, contrasting the teacher-centered approach. The book included lesson plans, transcriptions, and annotated comments for imperative instructional practices. Drawing from a range of effective instructional practices, it explores how student engagement and enjoyment in mathematics can be fostered through innovative lesson structures, activities, and discussions.

Unusual small bowel obstruction caused by gastric bezoar : a case report

여승현,정경원,박무인,김재현,김성은,문원,박선자,이승훈 대한내과학회 2019 대한내과학회 추계학술대회 Vol.2019 No.1

점막연관 림프조직 림프종양 일차성 위장관 소림프구성 림프종 1예

여승현,정경원,박무인,김성준,김재현,김성은,문원,박선자 대한소화기학회 2020 대한소화기학회지 Vol.75 No.4

Malignant lymphoma in the gastrointestinal tract is mainly secondary. Primary gastric malignant lymphoma constitutes 1-4% of gastric malignant tumors without specific endoscopic findings, and histopathologically, it is mainly classified as non-Hodgkin lymphoma of B-cell origin. Otherwise, a rare type of gastrointestinal lymphoma is small lymphocytic lymphoma (SLL). SLL is the same as a chronic lymphocytic lymphoma and tends to grow slowly. Here, we report a case of a patient diagnosed with primary gastrointestinal SLL upon endoscopy screening with non-specific mucosal findings.