• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1017-1023
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• 2013

With the growing use of smartphones, many secure applications are performed on smartphones such as banking, payment, authentication. To provide security services, cryptographic algorithms are performed on smartphones' CPU. However, smartphone's CPU has no considerations against side-channel attacks including Electromagnetic Analysis (EMA). In DesignCon 2012, G. Kenworthy introduced the risk of cryptographic algorithms operated on smartphone against EMA. In this paper, using improved experimental setups, we performed EMA experiments on androin smartphones' commercial secure applications. As a result, we show that the weakness of real application. According to the experimental setups, we picked up the operation of w-NAF scalar multiplication from the operation of Google's Play Store application using radiated EM signal. Also, we distinguished scalar values (0 or not) of w-NAF scalar multiplication.

• Korean journal of applied entomology
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• v.4
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• pp.25-28
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• 1965

The study was carried on a new disease of rice seedling which named 'Black rot of rice seedling'. None of papers on this disease was reported recently. The symptom of this disease was quite different from other seedling rot of rice plant. Submerged mycelial growth in water was black colored and it was surrounded whole surface of seed. Soil on which diseased seedlings were placed was black colored by this disease and the seedlings, finally stopped to grow within 3 em in height, and appeared with black rot symptom. Sporulation of the pathogen does not occurred under both of natural and artificial conditions. The mycelium appeared in dark color and with distinguished septation under the microscope. With those results it is easily recognized that the pathogen does not belong to those which causal organism:; of other seedling rot of rice plant like as Phycomycetes or Fusarium species. The study should be continued on identification of the causal organism. Favorable environments for the disease did not differ from other seedling rot of rice plant, and varietal resistance also did not significantly differ among the varieties used in this experiment. Dissemination of the disease was carried out not by planted seeds but by infected soil.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.1
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• pp.59-68
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• 2016

For comparison of tetracycline-resistant ($Tc^R$) genes, we obtained 21 and 14 $Tc^R$ Staphylococcus spp. from marine environment and human patient, respectively. Although all isolates from human were identified as Staphylococcus aureus, higher proportion of $Tc^R$ isolates (12 out of 14) from human were utilizing tet(M) gene compared to that of $Tc^R$ isolates (6 out of 21) from marine environment. Additionally, collaborated utilization of tet(M) and erm(A) in $Tc^R-Em^R$ S. aureus in human patient, but not in $Tc^R$ Staphylococcus spp. isolates from marine environment was also characterized. Based on the nucleotide sequence of transposon related to $Tc^R$ gene, we confirmed the origin of tet(M) gene in $Tc^R$ Staphylococci isolated from marine environments and human are derived from Tn916/1545-like and Tn5801 transposon, respectively. It is the first report showing the presence of Tn5801 in all $Tc^R$ S. aureus carrying tet(M) in human patient. Alignment of the fully sequenced tet(M) from marine environmental isolates was also agreed with the determined transposons by showing the genomic mosaic structure composed with three genomic parts from Tn916/1545 and unknown transposons. Genetic characteristics of these tet(M) in environmental isolates were similar to each other but different from those in isolates from human showing only tet(M) from Tn916/5801 type. It may imply the presence of less dramatic communication of antibiotic resistant genes between Staphylococci isolated from marine environment and human.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.586-594
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• 2013

This paper proposes a new coupling element of microwave slot coupler for designing waveguide slot array which can reduce the effect of undesired higher order mode coupling between coupling and radiating slots in the branch waveguide. The proposed device is composed of a centered longitudinal shunt-series coupling slot at the center of broad wall shared by two crossed rectangular waveguides and an asymmetric compound iris that excites the coupling slot. We first have obtained scattering parameters for the proposed coupler by use of EM S/W tool HFSS and then extracted the parameters of T- network equivalent circuit for the coupling slot. We also have analyzed the resonant properties such as resonant length and normalized admittance by changing the geometrical dimensions. The measured results for the fabricated coupler with short-circuited block ${\lambda}_g/4$ away from the coupling slot are well agreed with the simulated ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1031-1039
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• 2015

Present guided missiles are equipped with infrared seeker to find the infrared sources radiating from target plane and then chase, which results in an improvement of the hitting success rate when in striking target objects. To interrupt the chases from the guided missile, the target plane spreads the flare, avoiding the missile attracts. Our research is to develop a 2-color infrared identification technique to discern the flare and real thermal source from target plane. Considering flare radiation properties and EM atmosphere transmission rates, two channels were selected, in which main channel (MC) was in a range of 3.7 μm∼4.8 μm and auxiliary channel (AC) in 1.7 μm∼2.3 μm. A 2500K heat source was used for an artificial flare source, while a 570K heat source was utilized for airplane infrared source in experimental testing. Two infrared sensors detectable only at each chanel were employed in order to measure the voltage ratio from two channels, identifying the flare and real target plane via comparison the voltage ratio. Several experimental conditions were imported in order to prove that our proposed 2-color infrared identification technique is very efficient way to discern heat sources from aircraft and flare, demonstrating that our proposed technique is very promising means for our force’s InfraRed Counter Counter Measure (IRCCM) in order to countermeasure opposite force’s InfraRed Counter Measures (IRCM).

• Investigative Magnetic Resonance Imaging
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• v.24 no.3
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• pp.95-122
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• 2020

In this article, we evaluated the performance of radiofrequency (RF) coils in terms of the signal-to-noise ratio (S/N) and homogeneity of magnetic resonance images when used for ultrahigh-frequency (UHF) 7T magnetic resonance imaging (MRI). High-quality MRI can be obtained when these two basic requirements are met. However, because of the dielectric effect, 7T magnetic resonance imaging still produces essentially a non-uniform magnetic flux (|B₁|) density distribution. In general, heterogeneous and homogeneous RF coils may be designed using electromagnetic (EM) modeling. Heterogeneous coils, which are surface coils, are used in consideration of scalability in the |B₁| region with a high S/N as multichannel loop coils rather than selecting a single loop. Loop coils are considered state of the art for their simplicity yet effective |B₁|-field distribution and intensity. In addition, combining multiple loop coils allows phase arrays (PA). PA coils have gained great interest for use in receiving signals because of parallel imaging (PI) techniques, such as sensitivity encoding (SENSE) and generalized autocalibrating partial parallel acquisition (GRAPPA), which drastically reduce the acquisition time. With the introduction of a parallel transmit coil (pTx) system, a form of transceiver loop arrays has also been proposed. In this article, we discussed the applications and proposed designs of loop coils. RF homogeneous coils for volume imaging include Alderman-Grant resonators, birdcage coils, saddle coils, traveling wave coils, transmission line arrays, composite right-/left-handed arrays, and fusion coils. In this article, we also discussed the basic operation, design, and applications of these coils.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.1005-1018
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• 2017

This paper proposes an App Visualization (AppV) based on IoT Self-diagnosis Micro Control Unit (ISMCU) for accident prevention. It collects a current status of a vehicle through a sensor, visualizes it on a smart phone and prevents vehicles from accident. The AppV consists of 5 components. First, a Sensor Layer (SL) judges noxious gas from a current vehicle and a driver's driving habit by collecting data from various sensors such as an Accelerator Position Sensor, an O2 sensor, an Oil Pressure Sensor, etc. and computing the concentration of the CO collected by a semiconductor gas sensor. Second, a Wireless Sensor Communication Layer (WSCL) supports Zigbee, Wi-Fi, and Bluetooth protocol so that it may transfer the sensor data collected in the SL to ISMCU and the data in the ISMCU to a Mobile. Third, an ISMCU integrates the transferred sensor information and transfers the integrated result to a Mobile. Fourth, a Mobile App Block Programming Tool (MABPT) is an independent App generation tool that changes to visual data just the vehicle information which drivers want from a smart phone. Fifth, an Embedded Module (EM) records the data collected through a Smart Phone real time in a Cloud Server. Therefore, because the AppV checks a vehicle' fault and bad driving habits that are not known from sensors and performs self-diagnosis through a mobile, it can reduce time and cost spending on accidents caused by a vehicle's fault and noxious gas emitted to the outside.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.69-76
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• 2008

The biggest strength of the Internet is to enable to access information without any limitation of time and space. As the Internet and IT technologies have been developed, various kinds of teaching ways in education field such as remote lectures, video lectures, and CAI(Computer Adapted Instruction) have emerged. In terms of education, evaluation can be a basic foundation to help teach students in the next learning stage according to each student's level. In addition, it is able to give the information of students'abilities and provides proper learning programs to teach students on a case-by-case basis. The purpose of the paper is to establish evaluation system on the WWW(World Wide Web) that can reflect learning activities part of students in their evaluation scores based on the two important learning theories, Behaviorism and constructivism, which are mainly used in evaluation procedures to judge learning ability of students. This system will give information about learners, and analyze the learning interest of learners. The proposed system enables teachers to evaluate learning ability of students through various kinds of information of learners, and to execute level-based education.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.22-23
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• 2002

Titanium은 높은 강도, 낮은 밀도, 부식에 대한 저항 등, 타 금속에 비해 월등히 뛰어난 성질을 가지고 있기 때문에 산업 전반에 거쳐 그 응용이 크게 증가하고 있으며, 특히 고온에서의 응용이 중요성을 띠게 됨에 따라 고온으로의 상전이 관계에 따른 구조적 규명이 필요하다. 순수한 titanium은 상온에서 조밀충진 육방정계의 α-상구조(a=2.953Å, c=4.683 Å, P6₃/mmc)를 이루고 있으나, 대략 880℃ 이상에서는 β-상의 체심입방정계 (a=3.320Å, Im3m)로 상전이가 되는 것으로 알려져 있다. 이에 대한 대부분의 연구가 kinetics와 thermodynamics에 관련되어 있으며, TEM을 이용한 직접가열실험은 거의 전무한 상태이다. 본 실험에서는 TEM 직접가열을 통하여 titanium의 고온에서의 상전이와 가열시 발생할 수 있는 산화층 형성을 연구하였다. TEM 시편은 순도 99.94％의 titanium foil(Alfa Aesar, ＃00360, 0.025mm thick)를 이용하였고, 분석 장비로는 에너지여과 기능이 있는 TEM(EM912 Omega, Carl Zeiss)과 Gatan사의 double-tilt heating holder를 사용하였다. Titanium의 상전이를 관찰하기 위해 900℃ 까지 분당 10℃ 의 속도로 가열을 하였다. 통계적 분석 오차를 줄이기 위해 서로 다른 4군데의 관찰영역을 선택하여, 상온 - 600℃ - 900℃ - 상온의 단계별로 회절패턴을 관찰 및 기록하였고, 발생 가능한 산화에 대해서는 동일한 장비를 사용하여 EDS 분석을 하였다. 상온에서의 서로 다른 영역의 회절패턴들은 결함의 존재에 상관없이, 온도가 증가함에 따라 그 결함수가 증가하게 된다. 특히 600℃ 에서는 쌍정과 관련된 회절점들이 본래의 회절점 주위에 형성되어있지만, 각 면들의 격자상수의 변화는 나타나지 않았다. 그러나 900℃ 에서는 쌍정에 의한 회절점의 수가 증가하며, 회절점 사이에 발달한 뚜렷한 막대모양의 강도분포와 격자상수의 변화를 관찰할 수 있었다. 다시 상온으로 냉각시킨 후 관찰한 각각의 회절패턴에서는 격자 상수의 감소와 함께 900℃에 보여진 막대 모양의 강도분포와 쌍정에 의한 회절점들이 여전히 남아있었다. EDS분석 결과 가열 실험을 통해 시편이 열적 산화가 되어 있음을 확인 할 수 있었다. 순수한 titanium의 α-상에서 β-상으로의 상전이를 파악할 수 있는 격자상수의 변화자체는 매우 작은 값이기 때문에 상온과 900℃ 에서 기록된 전자회절패턴 상에서의 면간거리와 면간각도의 측정만으로는 상전이 여부를 명확히 구별할 수 없었다. 그러나, 결함에 의한 상변화가 900℃ 에서 심하게 관찰되어지는 것은 상전이와 관계가 있는 것으로 볼 수 있다. 고온에서 상온으로의 가역적 반응을 관찰할 수 없었던 이유는 열적산화로 생긴 산화층의 산소원자들이 고온의 상전이 과정 중에 Ti 원자와 반응이 일어나 TiO/sub X/ 구조로 전이되었기 때문으로 추정하고 있다.

• Journal of Korean Society for Geospatial Information Science
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• v.3 no.2 s.6
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• pp.15-28
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• 1995

The GPS positioning involves not only 'natural' errors associated with the satellites position errors, refraction of EM wave in the ionosphere, etc., but also 'artificial' errors associated with the operation of S/A (Selective Availability). In this paper, we present the principles, accuracies and applicabilities of our personal DGPS method, which employs the position-correction method on the GPS positionings data collected at the reference and the remote sites. The essential requirement of our DGPS method is that two GPS receivers should utilize the identical Navstar satellites at the same time. The positioning error (1 drms) of the stand-alone GPS is of an order of a few tens meters, while that of horizontal position by our DGPS method is about 1m and that of vertical position is about 2m We applied out DGPS technique in positioning moving objects, and obtained satisfactory results in tracking the trajectories of a car on the road and the those of drifters in the sea.