• 한국과학교육학회지
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• 제23권3호
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• pp.254-264
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• 2003

실험활동은 과학교육에서 중요한 요소로서, 그 목적과 효과에 대해 많은 논의가 있어왔다. 그러나 이에 관한 연구결과는 회의적이며 그 이유 중 하나는 하나의 실험은 동시에 다양한 목적을 성취할 수 없으며, 교사와 학생들이 실험의 목적에 대해 인식하고 있지 않기 때문이라는 것이다. 그러므로 본 연구에서는 시험의 목적에 대한 중학생들의 인식을 조사하였다. 실험의 목적에 대한 중학생들의 인식을 알아보기 위해 '과학자들의 실험'과 '학교실험'의 두 가지 상황에 대해 서울 소재 중학교 1학년생 147명을 대상으로 실험의 목적에 대해 서술형으로 응답하도록 하였다. 응답을 분석한 결과, 학생들의 56.8%가 과학자들이 새로운 것을 발견하거나 발명하기 위해 시험을 하는 것으로 응답하였으며, 학교실험에 대해서는 82.9%의 학생들이 인지적 영역, 즉 교과서에서 배운 것을 이해하거나 암기하기 위한 것이라고 응답하였다. 성별과 성취도에 따른 응답비율의 차이를 조사한 결과 남학생들의 경우에는 사회적 유용성을, 여학생의 경우에는 개인적 즐거움을 더 많이 응답하였다. 과학자의 시험과 학교실험에 대한 인식의 상화관련을 조사한 결과, 과학자들의 실험이 이론을 증명하는 것이라고 생각하는 학생은 학교 시험의 기능도 유사하게 생각하였다. 마지막으로 학생들의 응답을 정성적으로 분석하였으며, 결론적으로 학생들은 실험에 대해 다양하고 적절한 인식을 가지고 있지 못하며, 학교실험에 대해 회의적인 태도를 보이기도 하였다. 이를 개선하기 위해서 교사는 시험의 다양한 목적에 대해 학생들에게 알려주고, 매 시험마다 그 실험의 목적에 대해 명확히 밝혀야 할 것이다.

• 한국초등과학교육학회지:초등과학교육
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• 제38권2호
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• pp.203-215
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• 2019

The purpose of this study is to clarify the roles of laboratory work in school. Twenty-one literatures were identified about roles of laboratory work in school by applying criteria such as published in CI level journals or used as a reference over 100 times during 1960-2017. Twenty-one literatures were reviewed according to periods such as 1960-1989, 1990-2003, and 2004-2017, and identified the roles of laboratory work in school that commonly presented in more than two literature. Seven roles of laboratory work in school identified were as follows (a) learning scientific knowledge, (b) enhancing attitude toward science, (c) learning scientific inquiry methods, (d) acquiring skills to use specific laboratory instruments, (e) enhancing scientific attitude, (f) understanding the nature of science(NOS), and (g) providing opportunity to experience natural or scientific phenomena. The results of this study can be used to provide school teachers and students a clear meaning of the roles of laboratory work in school.

• 대한화학회지
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• 제54권5호
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• pp.643-649
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• 2010

이 연구에서는 고등학생들의 이론과 자료에 대한 인식론적 관점과 과학 과정 기술, 선호하는 실험 학습 환경에 대한 인식, 실험 수업에 대한 태도 사이의 관계를 조사하였다. 연구 결과, 과학 과정 기술, 선호하는 실험 학습 환경에 대한 인식의 모든 하위 범주(응집성, 개방성, 통합성, 준칙성, 물리적 환경), 실험 수업에 대한 태도는 이론과 자료에 대한 인식론적 관점과 유의미한 상관이 있었다. 중다 회귀 분석 결과, 과학 과정 기술, 선호하는 실험 학습 환경에 대한 인식의 하위 범주 중 개방성과 물리적 환경, 실험 수업에 대한 태도가 이론과 자료에 대한 인식론적 관점을 유의미하게 예측하였다.

• 한국과학교육학회지
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• 제4권1호
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• pp.15-25
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• 1984

The purpose of this study is to develop a practical and ideal model of science laboratory enrolled 48-60 students by studying optimal facilities such as laboratory tables and chairs proper to elementary school settings. The science laboratory model was figured out in terms of the following six procedures; (1) Current status as well as problems of science laboratory and its facilities was identified by means of the questionnaires conducted to 201 elementary schools, using stratified cluster sampling tehnique, under the consideration of the school size and the regional characteristics across the country. (2) Collected were the anthropometric data with respect to sitting height, popliteal height, buttock popliteal length, elbow rest height, and back width from the 747 students, 4th-6th grade, in Seoul area. (3) It was measured the work apace necessary for individual student to perform his experiment. (4) Using the data of the process (2), we determined the optimal sizes of laboratory tables and chairs fitted for Korean elementary school students. (5) The optimal area of science laboratory for 48-60 students is determined in terms of the data obtained in (3) for individual work space in addition to the appropriate table size figured out by (4). (6) A practical and ideal model for a science laboratory in elementary school was designed according to the above procedures. For the optimal model of science laboratory, the results of this study can be summarized as follows: The sizes of chair and table are categorized into three groups such as small, medium, and large depending on students' physical outfit. The small size base on the 12.5th percentile point of students' sitting height is used for students of the 0-25th percentile ranks. The medium size base on the 50th percentile point of students' sitting height is used for students of the 26-75th percentile ranks. The large size base on the 87.5th percentile point of students' sitting height is used for students of the 76-100th percentile ranks. (1) Sizes of chairs: The small size is 28cm in width and 33cm in height. The medium size is 31cm in width and 36cm in height. The large size is 35cm in width and 38cm in height. (2) Sizes of laboratory tables: The small size is 120cm in length, 86cm in width, and 60cm in height. The large size is 120cm in length, 86cm in width, and 60cm in height. The large size is 120cm in length, 86cm in width, and 65cm in height. (3) Size of science laboratory: The optimal science laboratory for 48-60 elementary school students, which can install the 12 laboratory tables, is 12m in length and 10m in width.

• BMB Reports
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• 제42권6호
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• pp.344-349
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• 2009

Angiogenesis is crucial for solid tumor growth. By secreting angiogenic factors, tumor cells induce angiogenesis. However, targeting these angiogenic factors for cancer therapy is not always successful, suggesting that other factors may be involved in tumor angiogenesis. This work shows that 25 protein spots were differentially expressed by two-dimensional gel electrophoretic analysis when HepG2 cells induced endothelial cell differentiation to tube in vitro, and most of them were upregulated. Twenty-one proteins were identified with MALDITOF-MS, and the other four were identified by LTQ-MS/MS. Keratins were identified as one class of these upregulated proteins. Further study indicated that the expression of keratin 17 in cultured endothelial cells is likely microenvironment regulated, because its expression can be induced by HepG2 cells and bFGF as well as serum in culture media. Increased expression of keratins in endothelial cells, such as keratin 17, may contribute to the angiogenesis induced by HepG2 cells.

• Nuclear Engineering and Technology
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• 제52권5호
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• pp.937-946
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• 2020

The aim in the present work is to simulate accident scenarios of AP1000 during the small-break loss-of-coolant accident (SBLOCA) and investigate the performance and behavior of automatic depressurization system (ADS) during accidents by using MIDAC (The Module In-vessel Degradation severe accident Analysis Code). Four types of accidents with different hypothetical conditions were analyzed in this study. The impact on the thermal-hydraulic of the reactor coolant system (RCS), the passive core cooling system and core degradation was researched by comparing these types. The results show that the RCS depressurization becomes faster, the core makeup tanks (CMT) and accumulators (ACC) are activated earlier and the effect of gravity water injection is more obvious along with more ADS valves open. The open of the only ADS1-3 can't stop the core degradation on the basis of the first type of the accident. The open of ADS1-3 has a great impact on the injection time of ACC and CMT. The core can remain intact for a long time and the core degradation can be prevent by the open of ADS-4. The all results are significant and meaningful to understand the performance and behavior of the ADS during the typical SBLOCA.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1304-1317
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• 2020

The tubes in a heat exchanger, such as a steam generator (SG), are subjected to crossflow, and interaction between tubes and supports can happen, which can cause fretting wear of tubes. Although many experiments and models have been established, some detailed mechanisms are still not sufficiently clear. In this work, more attention is paid to obtain the regulation of impact and sliding in the complex process and many factors, such as excitation forces and clearances. The responses and contact forces were analyzed to obtain clear understanding of the influences of these factors. Room temperature tests in the air were established. The results show that the effect of clearance on the normal work rate is not monotonous and instead has two peaks. The force ratio can influence the normal work rate by changing the distribution of contact angles, which can result in higher sliding in the contact process. Fretting wear tests are conducted, and the wear surfaces are analyzed by a scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDX). The results of this work can serve as a reference for impactsliding contact analysis between AVBs and tubes in steam generators.

• Membrane and Water Treatment
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• 제7권3호
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• pp.209-221
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• 2016

As a highly hydrophilic fibrillar mineral in nature, attapulgite (ATP) is a promising new additive for preparation of ultrafiltration (UF) hybrid membrane. In this work, ATP particles, which were grafted with a new Gemini surfactant of Ethyl Stearate-di(octadecyl dimethyl ammonium chloride) to detach the crystal bundles to single crystal and enhance the uniform dispersion in an organic polymer matrix, were incorporated into poly(vinylidene fluoride) (PVDF) matrix, and PVDF/Gemini-ATP hybrid membranes for adsorptive removal of Ni(II) ions from aqueous solution were prepared via a phase inversion method. Chemical composition, crystalization and morphology of the modified ATP were characterized by Fourier transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and X-ray diffraction (XRD), respectively. The morphology of the hybrid membrane was characterized by Scanning electron microscopy (SEM), the performance of permeability, hydrophilicity and adsorption of Ni(II) ions were studied, and the adsorption kinetics of the PVDF/ATP hybrid membranes were particular concerned. The results showed that the hybrid membrane displayed a good thermal stability and hydrophilicity. Comparing with PVDF membrane, the hybrid membrane possessed good adsorption capacity for Ni(II) ions, and the adsorption kinetics fit well with Lagergren second-order equation.

• Nuclear Engineering and Technology
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• 제52권5호
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• pp.897-907
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• 2020

The flow characteristics of reactor fuel assembly always intrigue the designers and the experimentalists among the myriad phenomena that occur simultaneously in a nuclear core. In this work, the visual experimental method has been developed on the basis of refraction index matching (RIM) and particle image velocimetry (PIV) techniques to investigate the detailed flow characteristics in China fast reactor fuel subassembly. A 7-rod bundle of simulated fuel subassembly was fabricated for fine examination of flow characteristics in different subchannels. The experiments were performed at condition of Re=6500 (axial bulk velocity 1.6 m/s) and the fluid medium was maintained at 30℃ and 1.0 bar during operation. As for results, axial and lateral flow features were observed. It is shown that the spiral wire has an inhibitory effect on axial flow and significant intensity of lateral flow mixing effect is induced by the wire. The root mean square (RMS) of lateral velocity fluctuation was acquired after data processing, which indicates the strong turbulence characteristics in different flow subchannels.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권6호
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• pp.3230-3253
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• 2017

Android malware steals users' private information, and embedded unsafe advertisement (ad) libraries, which execute unsafe code causing damage to users. The majority of such traffic is HTTP and is mixed with other normal traffic, which makes the detection of malware and unsafe ad libraries a challenging problem. To address this problem, this work describes a novel HTTP traffic flow mining approach to detect and categorize Android malware and unsafe ad library. This work designed AndroCollector, which can automatically execute the Android application (app) and collect the network traffic traces. From these traces, this work extracts HTTP traffic features along three important dimensions: quantitative, timing, and semantic and use these features for characterizing malware and unsafe ad libraries. Based on these HTTP traffic features, this work describes a supervised classification scheme for detecting malware and unsafe ad libraries. In addition, to help network operators, this work describes a fine-grained categorization method by generating fingerprints from HTTP request methods for each malware family and unsafe ad libraries. This work evaluated the scheme using HTTP traffic traces collected from 10778 Android apps. The experimental results show that the scheme can detect malware with 97% accuracy and unsafe ad libraries with 95% accuracy when tested on the popular third-party Android markets.