Sunghyun Cho

This article introduces various handover scenarios in multihop cellular networks. In addition, this article presents handover schemes where relay stations are located either inside a cell or on the boundary between two adjacent cells and investigates the effects of the deployment position of relay stations to handover performance. The simulation results show that multihop cellular networks for both deployment scenarios can achieve 90 percent throughput increase over single-hop cellular networks.

Vehicular ad-hoc networks (VANETs) have several security issues such as privacy preservation, secure authentication, and system reliability. In the VANET, a vehicle communicates with other vehicles or infrastructures using broadcasting messages. These messages contain not only normal traffic information, but also identification information of sender. In general, the identification information remains encrypted to ensure privacy. However, the conventional centralized system can decrypt the identi

Desalination is one of the most effective methods of supplying industrial water. Desalination has evolved into a feasible water supply alternative that allows the use of ocean water, and desalination plants operate in many countries, including in arid areas. Therefore, a large amount of desalination wastewater is generated, which is discharged into the sea. Since highly concentrated mineral ions in desalination wastewater are useful substitutes for carbon dioxide (CO2) and sulfur oxide (SOx) uti

Blockchain is a distributed ledger technology that provides data integrity to enable patient-centered health information exchange and access control. PIE systems integrate and manage fragmented patient EMRs through blockchain and protect users from security threats during the data exchange process among users. To increase safety and efficiency in the EMR-sharing process, we used access control using security levels, data encryption based on re-encryption, and a distributed data-sharing scheme.

A network composed of lightweight devices such as IoT has problems due to limited resources such as lack of storage space and low computing performance. These issues pose significant challenges in the application of robust security technologies, which reduces network security performance. The blockchain with strong security is a suitable technology to solve IoT problems with weak security. As a result, various research is being carried out to increase security, lightness, and efficiency of the I

Bluetooth low-energy–based beacons have two different roles: “broadcasting” (by beacon device) and “receiving” (by sensing devices). It allows devices to receive information over a short distance. Thus, many researchers are actively investigating positioning methods that use beacons. However, the distance value of positioning in the existing methods is not always accurate. This article proposes a novel three-dimensional positioning system using Bluetooth low-energy–based beacons. While the conve

Recently, cybercrimes that exploit the anonymity of blockchain are increasing. They steal blockchain users' assets, threaten the network's reliability, and destabilize the blockchain network. Therefore, it is necessary to detect blockchain cybercriminal accounts to protect users' assets and sustain the blockchain ecosystem. Many studies have been conducted to detect cybercriminal accounts in the blockchain network. They represented blockchain transaction records as homogeneous transaction graphs

Device-to-Device (D2D) communication technology has become a key factor in wireless sensor networks to form autonomous communication links among sensor nodes. Many research results for D2D have been presented to resolve different technical issues of D2D. Nevertheless, the previous works have not resolved the shortage of data rate and limited coverage of wireless sensor networks. Due to bandwidth shortages and limited communication coverage, 3rd Generation Partnership Project (3GPP) has introduce

Fluidized bed incinerators are more efficient and safe for treating explosive waste than previous methods because they can emit nitrogen oxide (NOx) concentrations below the standard value (90 ppm). However, a limitation is that they have only focused on optimizing the operating conditions to minimize NOx emission concentrations till now. In this situation, it is crucial to balance NOx and process costs. Therefore, this study designed an explosive waste incineration process and performed multi-o

Ensuring the security and usability of electronic health records (EHRs) is important in health information exchange (HIE) systems that handle healthcare records. This study addressed the need to balance privacy preserving and data usability in blockchain-based HIE systems. We propose a searchable blockchain-based HIE system that enhances privacy preserving while improving data usability. The proposed methodology includes users collecting healthcare information (HI) from various Internet of Medic

We consider hard handoff scheme based on uplink and downlink signals in IEEE 802.16e systems. To exploit the channel reciprocity in TDD systems, the proposed scheme triggers handoff initiation process using uplink signal. A serving base station monitors uplink traffic signal and triggers handoff process when the uplink signal strength or SINR becomes less than the predetermined level. This process can prevent mobile stations from periodically monitoring and reporting downlink signals of neighbor

Wireless multimedia sensor networks (WMSNs) have been improved with the increase of multimedia data. In WMSNs, a centralization problem can occur because of large-size multimedia data. It is necessary to consider device-to-device (D2D) communication. We focus on D2D WMSN based on cellular networks. Sensors in the D2D WMSN can non-orthogonally use a cellular link, which is a wireless communication channel between a sensor and an aggregator, and a D2D link, which is the channel between sensors. As