• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.653-663
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• 2002

The signature-then-encryption based on RSA scheme provides forward secrecy, but requires 4 modulo exponentiation operations in total, and the signcryption scheme proposed by Zheng simultaneously fulfills both the functions of digital signature and symmetric key encryption in a logically single step, and with a computational cost significantly smaller than that required by the current standard signature-then-encryption, but it can not provide forward secrecy. In this paper, we propose an enhanced signcryption scheme which can provide forward secrecy with lower computational cost and lower communication overhead comparing with those of the signature-then-encryption based on RSA, and with a similar communication overhead of Zheng's scheme. The proposed scheme can be also easily modified to the direct signature verification scheme by the recipient without using the recipient's private key. Additionally, we suggest a new design protocol with server-supported signatures which solves the CRLs(Certificate Revocation Lists) burden and provides non-repudiation of origin. This protocol with server-supported signatures also can be applied to the original signcryption scheme proposed by Zheng in order to improve security.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.1-10
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• 2007

The purpose of this study was to examine the differences of lower limbs muscle activities depending on three walking speeds of 2.5km/h, 5.0km/h and 7.5km/h during forward walking and backward walking making 14 students the subjects of this study. To achieve this aim, surface electrodes for factor analysis of EMG were adhered to rectus femoris, biceps femoris, tibialis anterior and gastrocnemius medial head of right lower limbs. The conclusions through this study are as follows. 1) The muscle activity of rectus femoris was higher in backward walking group than in forward walking group and it was the highest at 7.5km/h walking speed. 2) The muscle activity of biceps femoris was higher in forward walking group than in backward walking group. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed. 3) The muscle activity of tibialis anterior was higher in backward walking group than in forward walking group. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed. 4) The muscle activity of gastrocnemius medial head was higher in backward walking group than in forward walking group except P2. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed.

• Journal of the Korea Society of Computer and Information
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• v.28 no.8
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• pp.87-93
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• 2023

In this paper, we propose a system that accurately and efficiently determines forward head posture based on network learning by analyzing the user's skeletal posture. Forward head posture syndrome is a condition in which the forward head posture is changed by keeping the neck in a bent forward position for a long time, causing pain in the back, shoulders, and lower back, and it is known that daily posture habits are more effective than surgery or drug treatment. Existing methods use convolutional neural networks using webcams, and these approaches are affected by the brightness, lighting, skin color, etc. of the image, so there is a problem that they are only performed for a specific person. To alleviate this problem, this paper extracts the skeleton from the image and learns the data corresponding to the side rather than the frontal view to find the forward head posture more efficiently and accurately than the previous method. The results show that the accuracy is improved in various experimental scenes compared to the previous method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.36-43
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• 2011

The forward collision of vehicles in high speed can cause a chain collisions and high fatality rate. Most of the forward collisions are caused by insufficient braking distance due to detection time of driver and safe distance. Also, accumulated detection time of driver is cause of chain collisions after the forward collision. The FVCWS prevents the forward collision by maintaining the safety distance inter-vehicle and reducing detection time of driver. However the FVCWS can cause chain collisions because the system that interacts only forward vehicle has accumulated detection time of driver. In this paper, we analyze forward and chain collisions of normal vehicles and FVCWS vehicles on static traveling scenario. And then, we analyze and compare V2V based FVCWS with them after explaining the system. The V2V FVCWS reduces detection time of driver alike FVCWS as well as remove accumulated detection time of driver by broadcasting emergence message to backward vehicles at the same time. Therefore, the system decrease possibility of forward and chain collisions. All backward normal vehicles and 3~4 backward FVCWS vehicles have possibility of forward and chain collisions in result of analysis. However V2V FVCWS vehicles almost do not chain collisions in the result.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.795-807
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• 2020

The more liquid the capital market, the more attractive it will be for investors to place their money in the capital market. Therefore, the purpose of this study is to investigate the factors that influence stock liquidity of manufacturing sector companies listed on the stock exchange in Indonesia. The independent variables used in this study are forward-looking information disclosure, institutional ownership, foreign ownership, and board activity with information asymmetry as an intervening variable and stock liquidity as the dependent variable. The population of this study is manufacturing sector companies listed on the Indonesian stock exchange (IDX). Samples are selected based on the random sampling method, and the number of samples is calculated based on the Slovin formula. The sample was 59 manufacturers, and data was annual reports (for 2 years) and stock transactions from 2016 to 2017. The results of the study showed that forward-looking information disclosure had a significant effect on information asymmetry. Information asymmetry and foreign ownership have a significant impact on stock liquidity, whereas information asymmetry mediates the relationship between forward-looking disclosures and stock liquidity. Furthermore, the accuracy of information about the certainty of business activity both now and in the future can instill confidence in stakeholders in interacting and cooperating.

• The Journal of Korean Physical Therapy
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• v.29 no.4
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• pp.153-157
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• 2017

Purpose: The purpose of this study was to investigate the effect of self-postural control on foot pressure in subjects with forward head posture. Methods: Forty-two healthy adults were recruited in this study. Participants were divided into two groups: The forward-head postural (FHP) group (craniovertebral angle<$53^{\circ}$, n=22) and the control group (craniovertebral angle${\geq}53^{\circ}$, n=20). In the FHP group, foot pressure was measured using three different standing postures: Comfortable standing posture (CSP), subjective neutral standing posture (SNSP), and neutral standing posture with visual feedback (NSP-VP). Each position was performed in random order. In the control group, foot pressure was measured only using the comfortable standing posture. Results: With respect to CSP and SNSP, there was a significant difference on heel pressure between the two groups (p<0.05). Regarding NSP-VP, however, there was no significant differences on heel pressure between the two groups (p>0.05). Conclusion: We suggest that cervical posture control using visual feedback has a positive effect on the distribution of foot pressure in subjects with forward head posture.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.464-469
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• 2001

This work provides the biomechanical evaluations of a manual wheelchair with a bi-directional driving system. The new propulsion strategy can be accomplished by employing a special gear system that converts the oscillatory motion of a handrim into the unidirectional output motion of a wheel. A main feature of the forward. backward propulsion is to supply continuous driving torque without break. Motion. analysis has been performed through 2-dimensional image processing for measuring the kinematic properties of the upper arm and fore arm. Then, the inverse dynamics analysis has been done for obtaining the joint torques, the handrim forces and input/output powers. Results show that the output power by the forward. reverse propulsion is almost twice as much as that by conventional propulsion. Also, the new propulsion is expected to reduce the fatigues and injuries at arm joints by employing more muscle groups for movement. In conclusion, the forward. reverse propulsion can greatly improve the performances of manual wheelchairs by providing better mobility as well as by guaranteeing several advantages from a biomechanical viewpoint. Future development of a manual wheelchair optimized for the bi-directional propulsion will further improve the propulsion performances.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.63-68
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• 2017

This paper reviews the learning model of a forward slip ratio in order to improve the mass-flow stability and strip qualities in the hot strip finishing mill process. Firstly, it is shown, from mathematical analysis, that the significant parameters of the forward slip ratio are the tension, looper angle, and roll velocity. Secondly, a discrete-time learning model of the forward slip ratio is proposed from these parameters, which is identified by an instrumental variable (IV) identification algorithm. Finally, it is shown from computer simulation that the proposed learning model is more effective than the existing learning model.

• The Journal of Korean Physical Therapy
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• v.28 no.5
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• pp.292-296
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• 2016

Purpose: This study was conducted to investigate the effects of modified cervical exercise on respiratory functions in smartphone users with forward head posture. Methods: Thirty-three smartphone users with forward head posture participated in this study. Subjects were divided into three groups that performed modified cervical exercise one time a day (A group), two times a day (B group), and three times a day (C group). All subjects performed the exercise for four weeks, during which time respiratory functions were measured. Results: There were significant differences in respiratory functions such as forced vital capacity, forced expiratory volume at one second, and maximal voluntary ventilation in the C group after four weeks (p<0.05). Moreover, the forced vital capacity differed among groups, and the post hoc test revealed a significant difference between A group and C group (p<0.05). Conclusion: The results of this study confirmed that modified cervical exercise improved respiratory functions in smartphone users with forward head posture. These findings indicate that smartphone users with forward head posture should perform modified cervical exercise to build correct posture and respiratory functions.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.3
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• pp.1-9
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• 2016

PURPOSE: The purpose of this study was to identify the effects on flexibility of bridge and plank exercises using sling suspension on an unstable surface. METHODS: The subjects of this study were 20 healthy adults in their 20s (plank=10, bridge=10). Both types of exercise were performed three times per week for a period of four weeks. Each exercise was performed in the front and side direction. Exercise intensity was altered through the use of a sling, which was placed at the knee and ankle. Flexibility at trunk forward flexion and backward extension was measured. The trunk forward flexion was measured at sitting position. The trunk backward extension was measured at prone position. The data were analyzed by Two-way ANOVA. RESULTS: There were significant differences in the pre- and post-test for both the bridge and plank exercise groups. In the bridge exercise, significant differences were shown in the trunk forward flexion and the trunk backward extension (p<.05). In the plank exercise, a significant difference was shown in the trunk backward extension (p<.05). No significant differences were noted in interaction effect or the main effects in either group. CONCLUSION: Bridge and plank exercises on an unstable surface improve flexibility. The bridge exercise improves the flexibility of the forward and backward muscles of the trunk. The plank exercise improves the flexibility of the forward muscles of the trunk. This information would be useful in the development of exercise programs including bridge and plank exercises for improving flexibility and core stability.