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Automatic Fortified Password Generator System Using Special Characters
Jeong, Junho,Kim, Jung-Sook Korean Institute of Intelligent Systems 2015 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.15 No.4
The developed security scheme for user authentication, which uses both a password and the various devices, is always open by malicious user. In order to solve that problem, a keystroke dynamics is introduced. A person's keystroke has a unique pattern. That allows the use of keystroke dynamics to authenticate users. However, it has a problem to authenticate users because it has an accuracy problem. And many people use passwords, for which most of them use a simple word such as "password" or numbers such as "1234." Despite people already perceive that a simple password is not secure enough, they still use simple password because it is easy to use and to remember. And they have to use a secure password that includes special characters such as "#!($^*$)^". In this paper, we propose the automatic fortified password generator system which uses special characters and keystroke feature. At first, the keystroke feature is measured while user key in the password. After that, the feature of user's keystroke is classified. We measure the longest or the shortest interval time as user's keystroke feature. As that result, it is possible to change a simple password to a secure one simply by adding a special character to it according to the classified feature. This system is effective even when the cyber attacker knows the password.
Development of a fast-stabilized fuel injection system using a solenoid actuator
Junho Jeong,김근영,장병국,박기수 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10
A new fuel injection system with a solenoid actuator was developed to reduce jet stabilization times and was compared to a conventional fuel injection system using a fastacting valve. The jet stabilization time was examined from free-jet images obtained using a flow visualization technique. Using a supersonic wind tunnel, the jet establishment image and trajectory for supersonic flows were obtained. The jet stabilization times were obtained at fuel tank pressures of 500, 700, and 900 kPa and injection orifice diameters of 1 and 2 mm. For all cases, the jets were stabilized at 4-12 ms, which was shorter than the stabilization time (approximately 300 ms) of the conventional system. The injection pressure measurements and jet trajectory comparison showed that the new system could inject fuel at the target pressure more effectively than the conventional fuel system.
Junho Jeong,Kiwan Jang,HoSueb Lee,SoungSoo Yi,JungHyun Jeong,JongHo Park,Changdae Kim 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.6
KSrPO4:Eu2+x, Mn2+y and KSr(1-x-y)PO4:Eu2+x, Mn2+y phosphors (x = 0.01 and y = 0, 0.01, 0.02 and 0.03) were prepared using a solid state reaction method by taking non-stoichiometric and stoichiometric amounts, respectively, of Eu2+ and Mn2+ ions. The photoluminescence (PL) properties and the energy transfer Eu2+ → Mn2+ of the prepared samples were investigated for UV-based white-light-emitting diodes (UV-based LEDs). The emission spectrum shows an intense blue emission at 430 nm (λex = 356 nm) with a full width at half maximum (FWHM) of 40 nm for the KSrPO4:Eu2+x (x = 0.01) phosphor and at 427 nm (λex = 356 nm) with a FWHM of 31 nm for the KSr(1-x)PO4:Eu2+x (x = 0.01) phosphor. The efficiency of the energy transfer Eu2+ →Mn2+ of KSr(0.99-y)PO4:Eu2+0.01, Mn2+y (y = 0.01, 0.02 and 0.03) was very low. The observed results are discussed in connection with the occupation of sites by Eu2+ ions and the KSrPO4:Eu2+x phosphor prepared by using the non-stoichiometric doping method has been suggested to be more efficient for white-light UV-based LEDs.
Effect of outliers on the variable selection by the regularized regression
Jeong, Junho,Kim, Choongrak The Korean Statistical Society 2018 Communications for statistical applications and me Vol.25 No.2
Many studies exist on the influence of one or few observations on estimators in a variety of statistical models under the "large n, small p" setup; however, diagnostic issues in the regression models have been rarely studied in a high dimensional setup. In the high dimensional data, the influence of observations is more serious because the sample size n is significantly less than the number variables p. Here, we investigate the influence of observations on the least absolute shrinkage and selection operator (LASSO) estimates, suggested by Tibshirani (Journal of the Royal Statistical Society, Series B, 73, 273-282, 1996), and the influence of observations on selected variables by the LASSO in the high dimensional setup. We also derived an analytic expression for the influence of the k observation on LASSO estimates in simple linear regression. Numerical studies based on artificial data and real data are done for illustration. Numerical results showed that the influence of observations on the LASSO estimates and the selected variables by the LASSO in the high dimensional setup is more severe than that in the usual "large n, small p" setup.
Jeong, Junho,Kim, Seungkeun,Suk, Jinyoung Elsevier 2017 Acta astronautica Vol.141 No.-
<P><B>Abstract</B></P> <P>In order to overcome the limited range of GPS-based techniques, vision-based relative navigation methods have recently emerged as alternative approaches for a high Earth orbit (HEO) or deep space missions. Therefore, various vision-based relative navigation systems use for proximity operations between two spacecraft. For the implementation of these systems, a sensor placement problem can occur on the exterior of spacecraft due to its limited space. To deal with the sensor placement, this paper proposes a novel methodology for a vision-based relative navigation based on multiple position sensitive diode (PSD) sensors and multiple infrared beacon modules. For the proposed method, an iterated parametric study is used based on the farthest point optimization (FPO) and a constrained extended Kalman filter (CEKF). Each algorithm is applied to set the location of the sensors and to estimate relative positions and attitudes according to each combination by the PSDs and beacons. After that, scores for the sensor placement are calculated with respect to parameters: the number of the PSDs, number of the beacons, and accuracy of relative estimates. Then, the best scoring candidate is determined for the sensor placement. Moreover, the results of the iterated estimation show that the accuracy improves dramatically, as the number of the PSDs increases from one to three.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A sensor placement methodology is proposed for vision-based relative navigation. </LI> <LI> Multiple PSDs/beacons are used for relative navigation of satellite formation. </LI> <LI> Farthest point optimization (FPO) is applied to configure sensor locations. </LI> <LI> The methodology is comprised of the FPO and constrained Extended Kalman filter. </LI> <LI> The performance of relative navigation are analyzed depending on sensor locations. </LI> </UL> </P>
Automatic Fortified Password Generator System Using Special Characters
Junho Jeong,Jung-Sook Kim 한국지능시스템학회 2015 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.15 No.4
The developed security scheme for user authentication, which uses both a password and the various devices, is always open by malicious user. In order to solve that problem, a keystroke dynamics is introduced. A person’s keystroke has a unique pattern. That allows the use of keystroke dynamics to authenticate users. However, it has a problem to authenticate users because it has an accuracy problem. And many people use passwords, for which most of them use a simple word such as “password” or numbers such as “1234.” Despite people already perceive that a simple password is not secure enough, they still use simple password because it is easy to use and to remember. And they have to use a secure password that includes special characters such as “#!(*)ˆ”. In this paper, we propose the automatic fortified password generator system which uses special characters and keystroke feature. At first, the keystroke feature is measured while user key in the password. After that, the feature of user’s keystroke is classified. We measure the longest or the shortest interval time as user’s keystroke feature. As that result, it is possible to change a simple password to a secure one simply by adding a special character to it according to the classified feature. This system is effective even when the cyber attacker knows the password.