• Journal of The Korean Association For Science Education
• /
• v.25 no.3
• /
• pp.346-352
• /
• 2005

The purpose of this study was to develop problem-solving experiments and investigate the effects of these experiments on student attitudes. According to results the experiments were effective in changing student attitude from 'dead reckoners' to 'empiricists'. In addition, these experiments effectively changed perceptions about experiments, especially in the sub-categories of difference recognition, degree of inquiry, and use of debate.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.12 no.3
• /
• pp.378-387
• /
• 2009

The shaped charge consists of the cast or pressed explosive and the metal liner. The pressure formed in detonation wave is so high that the liner is collapsed and the jet of high temperature, pressure and velocity is produced. The jet penetrates the target. In this paper, the simulation for optimization of flexible linear shaped charge(FLSC) was carried out by AUTODYNE program. Based on the results of simulation, we made a prototype of FLSC and evaluated penetration performance, flexibility and its application. The test result of prototype was compared with that of simulation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.2
• /
• pp.188-195
• /
• 2010

Unlike using a single sonar platform, using two different sonar platforms can lead to a considerable increase of acoustic aperture in Passive Ranging Sonar(PRS). Values measured from two sonar platforms shall be consistent in order to allow us to rely on such improved aperture. However, obtaining consistent values from a towed array and a frank array is not always simple due to the heading error occurring at towed array. The objective of this paper is to verify a new criterion analyzing the consistency in the measured values of towed array and frank array through computer simulations.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.3
• /
• pp.378-386
• /
• 2014

In this paper, safety evaluation method simulating battlefield environment was studied to verify military operability of commercial lithium secondary battery. Based on the MIL-STD-2105D and STANAG standards, safety tests of lithium secondary battery module were conducted, such as bullet impact, fragment impact, fast cook-off and slow cook-off. All results satisfied the safety evaluation criteria, founded on military standard. It suggests that the lithium secondary module has high potential to be applied in a military power source. The safety evaluation methods developed in this paper can be valuable to propose the new military standards for commercial lithium secondary batteries.

• Journal of Integrative Natural Science
• /
• v.1 no.3
• /
• pp.221-229
• /
• 2008

본 논문에서는 기존의 개인 식별 방법의 한계를 해결하는 대안으로 떠오르고 있는 생체인식 기술 중 인식률이 뛰어나고 신뢰성 있는 홍채인식 시스템을 구현하고자 한다. 구현을 위하여 신호처리 분야에서 주로 사용되는 wavelet변환으로 계수 특징 값 추출을 하였으며, 인식률을 알아보기 위하여 신경망 기법을 이용하고자 한다. 그러나 신경망 기법에서 주로 사용되는 비선형 최적화기법인 Scale Conjugate Gradient는 최적화 문제점을 해결하기에는 수렴속도가 느리기 때문에 적합하지 않다. 따라서 본 논문에서는 기존 Scale Conjugate Gradient를 보완한 Levenberg-Marquardt Back-Propagation을 홍채인식에 적용하여 구현함으로써 인식율을 높이고자 한다. 적용한 알고리즘 구현으로 해의 수렴정도, 변수 벡터의 변화정도에 따라 크기를 적절히 변화시킴으로써 수렴속도를 개선하고, 효율성과 안정성을 동시에 얻을 수 있었다.

• Journal of Integrative Natural Science
• /
• v.1 no.3
• /
• pp.247-249
• /
• 2008

자성 결정체인 $Fe_3O_4$ 나노 입자를 합성하기위하여 강한 극성 용매인 2-pyrrolidone을 연전도 반응매개체로 하여 용액 내에 $FeCl_3{\cdot}6H_2O$을 용해시켜 2-pyrrolidone의 비등점까지 나노 결정체 고온 열분해 방법을 이용하여 제조되었다. 고온 열분해 후, $Fe_3O_4$ 나노 입자는 methanol/diethyl ether (1:3)에 의해서 침전되어졌다. 합성된 $Fe_3O_4$ 나노 입자는 고결정도, 고자기성을 가지고 있으며, 수용성의 자성 나노 결정체이다. 합성된 $Fe_3O_4$ 나노 입자의 크기와 결정도는 transmission electron microscope (TEM, Tecnai F20)를 이용하여 특성 분석하였으며, area electron diffraction (SAED) pattern과 HRTEM을 이용하여 나노입자의 격자 패턴 (lattice fringes)을 확인하였다.

• The Journal of Natural Sciences
• /
• v.13 no.1
• /
• pp.65-71
• /
• 2003

Angiotensive I-converting enzyme inhibitory activity of various extracts from some rice brans were investigated with its optimal extraction conditions. Water extracts of Ilpumbyeo rice bran showed the highest ACE inhibitory activities of 7730%. ACE inhibitor from Ilpumbyeo rice bran was maximally extracted when its powder was treated with 10 times of distilled water for 12h at $30^{\circ}C$.

• The Journal of Natural Sciences
• /
• v.9 no.1
• /
• pp.169-175
• /
• 1997

In this study, it was investigated about dyeability, light-fastness, wash-fastness and tensile strength in PET fiber using the effective carrier solvent such as benzyl alcohol, benzaldehyde and acetophenone. As a results, dyeability in mixed solvent was better than that of single solvent. And dyeability in mixed solvents of benzyl aldehyde and acetophenone was of them. But effective carrier action was resulted in decrease of properties such as light-fastness and tensile strength of PET fiber after dyeing.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.339-340
• /
• 2008

전자계가 인체건강에 미치는 영향에 대해 막연한 불안감을 갖고 있는 실정이다. 그러나 최근까지도 국내외 주요 동물실험 결과에서 어떠한 과학적 근거도 입증할 수 없는 상태이며, 세계보건기구(WHO)의 연구결과는 국제가이드라인을 반드시 지킬 것을 권장하고 있으며, 과학적 사실에 주의를 기울이면서 관련 연구프로그램을 장려하고, 자의적으로 낮은 노출제한치를 적용하는 것은 정당하지 않다고 발표하였다. 본고에서는 주요 동물실험결과, WHO 연구결과, 국내 전력설비별 전자계 노출현황, 대국민 인식조사 및 소송사례에 대해 검토하고 전자계의 안전성에 대해 고찰하고자 한다.

• Journal of Urban Science
• /
• v.9 no.1
• /
• pp.61-68
• /
• 2020

Steps are very common features in our living environment. Unfortunately, the occurrence of accidents on steps is thus inevitable. A failed visibility to recognize a step remains the most common attribute in these accidents. In this research, sensory scales of step visibility were created in order to examine the effects of two factors on step visibility in sensory testing methods; observation height from floor and eye condition while viewing a step from the descending direction. Results of sensory tests revealed strong influence of eye condition on step visibility. Influence of visual characteristics of each step was also examined and clarified.