• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.13 no.5
• /
• pp.147-157
• /
• 2003

We often use cryptographic systems on small devices such as mobile phones, smart cards and so on. But such devices are delicate against the tlreat of key exposure of secret keys. To reduce the damage caused by exposure of secret keys stored on such devices, the concept of forward security is introduced. In this Paper, we present a new forward secure signature scheme based on Gap Diffie-Hellman groups. Our scheme achieves security against chosen-message attacks under the computational Diffie-Hellman assumption in the random oracle model.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.21 no.5
• /
• pp.161-168
• /
• 2011

In 2009, Jeon et al proposed the lightweight strong authentication and strong privacy protocol, where the tag requrires only simple bitwise operations and random number generator. JK-RFID authentication protocol provides strong security: eavesdropping, replay, spoofing, Location tracking, DoS attack and forward security. Nevertheless, this paper points out the vulnerability of the forward security and improve the process of key updating. As a result, proposes an enhanced JK-RFID authentication protocol providing forward security and verify its satisfaction. In addition, a security and an efficiency of the proposed scheme analyze. Since partial adjustments of the key updating operation in JK-RFID authentication protocol, our protocol improve the forward security.

• Journal of International Academy of Physical Therapy Research
• /
• v.11 no.4
• /
• pp.2229-2236
• /
• 2020

Background: Few comparative studies have been conducted on strengthening the anterior and posterior muscles of the trunk via lumbar stabilization exercises. Objectives: To compare the effects of forward leaning exercise and supine bridging exercise in stability exercise. Design: Randomized controlled clinical trial (single blind). Methods: Thirty subjects with spondylolisthesis were participated in this study. Fifteen subjects performed the bridging exercises and fifteen subjects performed the forward leaning exercises. Each exercise was held for ten seconds per repetition, and four repetitions were considered one sub-session. A total of four sub-sessions were performed in one full exercise session. The full exercise session required thirty minutes, including rest time. Trunk strength and range of motion and Oswestry disability index were measured. Results: Two weeks later, trunk flexion strength and trunk extension range of motion were significantly increased in the forward leaning exercise group than in the supine bridging group, trunk extension strength were significantly increased in the supine bridging exercise group than in the forward leaning group. After two weeks, the pain score was significantly lower in the forward leaning exercise group than in the supine bridging group. Conclusion: This study has shown that stabilization exercises are effective in increasing range of motion and strength in spondylolisthesis subjects. It was especially confirmed that the method of strengthening the anterior muscles of the trunk is more effective than the standard stabilization exercise method.

• Current Optics and Photonics
• /
• v.6 no.3
• /
• pp.313-322
• /
• 2022

Remote-sensing optical payloads, especially hyperspectral imagers, have particular issues with stray light because they often encounter high-contrast target/background conditions, such as sun glint. While developing an optical payload, we usually apply several stray-light analysis methods, including forward and backward analyses, separately or in combination, to support lens design and optomechanical design. In addition, we often characterize the stray-light response over a full field to support calibration, or when developing an algorithm to correct stray-light errors. For this purpose, we usually use forward analysis across the entire field, but this requires a tremendous amount of computational time. In this paper, we propose a sequence of forward-backward-forward analyses to more effectively investigate the through-field response of stray light, utilizing the combined advantages of the individual methods. The application is an airborne hyperspectral imager for creating hyperspectral maps from 900 to 1700 nm in a 5-nm-continuous band. With the proposed method, we have investigated the through-field response of stray light to an effective accuracy of 0.1°, while reducing computation time to 1/17^th of that for a conventional, forward-only stray-light analysis.

• Journal of the Korean Society of Physical Medicine
• /
• v.16 no.2
• /
• pp.1-8
• /
• 2021

PURPOSE: This study examined the effects of changes in the head direction (forward, upward 10° and downward 10°) on the quadriceps, center of pressure (COP), and foot pressure during squat exercises. The aim was to determine if the head direction could better activate the quadriceps muscle and provide a safer and stable squat posture during squat exercise. METHODS: Fifteen healthy college students were asked to stand on a Zebris, and three electrodes for sEMG were attached to their vastus medialis oblique (VMO), vastus lateralis (VL), and rectus femoris (RF) muscles. The participants then performed squatting exercises under three head directions (forward, upward 10°, and downward 10°). Surface electrodes were then used to record the EMG data during exercise. The Zebris FDM-SX was used to measure the foot pressure and COP of the participants. RESULTS: In squat exercise, the upward head direction group showed significantly higher VL activation than the downward head direction group (p < .05). The upward head direction group showed a significant backward change in the deviation of the COP than the downward and forward groups (p < .05). The upward head direction group showed a significant decrease in forefoot pressure than the downward and forward groups (p < .05) and an increase in the hindfoot pressure compared to the downward and forward groups (p < .05). CONCLUSION: The head direction upward in squat exercise has a positive effect on the quadriceps.

• PNF and Movement
• /
• v.20 no.3
• /
• pp.331-340
• /
• 2022

Purpose: Thisstudy aimed to identify the effect of varying the expansibility of elastic tape on the onset time of muscle contraction during neck extension for forward head posture syndrome. Methods: Forty-five young adults with forward head posture syndrome volunteered to participate and were randomly assigned to one of three groups according to the expansibility of the elastic tape (25%, 50%, 75%). The onset time of muscle contraction for the neck extensor during neck extension was measured using an electromyographic system (Free EMG, BTS, Italy). Multivariate analysis of variance was employed to determine the effect of different expansibilities of elastic tape on the onset time of muscle contraction during neck extension for forward head posture syndrome. When there was a statistically significant difference by MANOVA, Scheffe was used as a post-hoc test. The level of significance was set at α=0.05. Results: In the comparison of the onset time of muscle contraction of varying elastic tape expansibilities and measurement times, there was a significant difference between the groups (Lt. UT, Lt. SCM, Rt. SCM) (p < 0.05), but there was no significant difference in the interaction between the measurement time and the group, between the measurement time (p > 0.05). Conclusion: In the neck extension, 75% of the tape extensibility in the Lt. UT and both SCM shortened the muscle contraction onset time.

• Journal of applied mathematics & informatics
• /
• v.25 no.1_2
• /
• pp.415-424
• /
• 2007

The generalized inverses have many important applications in the aspects of theoretic research and numerical computations and therefore they were studied by many authors. In this paper we get some necessary and sufficient conditions of the forward order law for {1}-inverse of multiple matrices products $A\;=\;A_1A_2{\cdots}A_n$ by using the maximal rank of generalized Schur complement.

• The Journal of the Acoustical Society of Korea
• /
• v.15 no.2E
• /
• pp.76-84
• /
• 1996

The experimental testing results of the large-scale version of a forward-looking ultrasound imaging catheter(FLUIC) are presented, along with the fabrication techniques used, experimental methods, and comparisons of the measured and simulated results. The transducer model is verified by measuring the electrical impedance of the transducer. The pulse width, beamwidth, and the dynamic range for both transmit and pulse-echo response of the fabricated FLUIC are also analyzed. The experimental results conformed its forward-looking imaging capability and the sources of discrepancies between the simulated and experimental beam profiles are addressed.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.242-246
• /
• 2001

The alternated forward multi resonant converter (AT forward MRC) is studied on the transient response and the measured loop gain for stability. The compensator is composed of the error amplifier with 3 poles and 2 zeros. This is optimized through the experiment with HP4194A network analyzer. We are initiated by the thinking of how to make the stabilization from the experimental results of loop gain curves. The loop gain, low frequency gain and gain margin are more improved through the experimental considerations. Also, the transient response is more enhanced effectively.

• The KSFM Journal of Fluid Machinery
• /
• v.4 no.1 s.10
• /
• pp.46-51
• /
• 2001

The revision is proposed for forward curved bladed fans in order to make the KS B 6326 established in 1987 in agreements with newly revised KS standards. This proposal includes modification of Aplication range, numbering system, classification based on performance, and allowing dimensions for specified sizes.