• Convergence Security Journal
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• v.21 no.1
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• pp.55-62
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• 2021

Recently, the use of sensor devices is gradually increasing. As various sensor device emerge and the related technologies advance, there has been a dramatic increase in the interest in heterogeneous wireless sensor networks (WSNs). While sensor device provide us many valuable benefits, automatically and remotely supported services offered and accessed remotely through WSNs also exposes us to many different types of security threats. Most security threats were just related to information leakage and the loss of authentication among the involved parties: users, sensors and gateways. An user authentication protocol for wireless sensor networks is designed to restrict access to the sensor data only to user. In 2019, Chen et al. proposed an efficient user authentication protocol. However, Ryu et al. show that it's scheme still unstable and inefficient. It cannot resist offline password guessing attack and session key attack. In this paper, we propose an improved protocol to overcome these security weaknesses by storing secret data in device. In addition, security properties like session-key security, perfect forward secrecy, known-key security and resistance against offline password attacks are implied by our protocol.

• The Journal of Korean Medical History
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• v.34 no.2
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• pp.89-96
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• 2021

This research aims to find a way to utilize the literature to select the herbs to be added or subtracted according to the condition of the patient after determining the basic prescription to be used for the patient. The study is based on data concerning the herbal composition and application of prescriptions described in the Donguibogam. The composition herbs was expressed as a weight ratio, the standard deviation of the weight ratio was calculated for each prescription, and the case where the weight ratio was greater than the base value (highest weight ratio - standard deviation) was designated as a principal herb. The various expressions of applications were changed to representative terms by the researcher and used to calculate the frequency. Of the 4,373 prescriptions for Donguibogam, 3,307 were able to be expressed in terms of weight ratios with 640 prescriptions using Rehmannia glutinosa, Cnidium officinale, Angelica gigas and Paeonia lactiflora as the principle herb. Of the 640 prescriptions, 508 prescriptions included applied information. Rehmannia glutinosa can also be used for symptoms such as fetal leakage(胎漏), short ingestion(食少), fever(發熱), dazed expression(眼花). Cnidium officinale can also be used for symptoms such as migraine(偏頭痛), stroke(中風癱瘓), tetanus(破傷風). Angelica gigas can also be used for symptoms such as forgetfulness(健忘), incontinence of urination(小便不通), palpitations(驚悸). Paeonia lactiflora can also be used for symptoms such as heart pain and abdominal pain(心腹痛), cough(咳嗽).

• Journal of Trauma and Injury
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• v.32 no.1
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• pp.26-31
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• 2019

Purpose: Rhabdomyolysis (RB) is a syndrome characterized by the decomposition of striated muscles and leakage of their contents into the bloodstream. Acute kidney injury (AKI) is the most significant and serious complication of RB and is a major cause of mortality in patients with RB. Severe RB (creatine kinase [CK] ${\geq}5,000$) has been associated with AKI. However, early prediction is difficult because CK can reach peak levels 1-3 days after the trauma. Hence, the aim of our study was to identify predictors of severe RB using initial patient information and parameters. Methods: We retrospectively analyzed 1,023 blunt trauma patients admitted to a single tertiary hospital between August 2011 and March 2018. Patients with previously diagnosed chronic kidney disease were excluded from the study. RB and severe RB were defined as a CK level ${\geq}1,000U/L$ and ${\geq}5,000U/L$, respectively. The diagnosis of AKI was based on RIFLE criteria. Results: The overall incidence of RB and severe RB was 31.3% (n=320) and 6.2% (n=63), respectively. On multivariable analysis, male sex (odds ratio [OR] 3.78, 95% confidence interval [CI] 1.43 to 10.00), initial base excess (OR 0.85, 95% CI 0.80 to 0.90), initial CK (OR 2.07, 95% CI 1.67 to 2.57), and extremity abbreviated injury scale score (OR 1.78, 95% CI 1.39 to 2.29) were found to predict severe RB. The results of receiver operating characteristic analysis showed that the best cutoff value for the initial serum CK level predictive of severe RB was 1,494 U/L. Conclusions: Male patients with severe extremity injuries, low base excess, and initial CK level >1,500 U/L should receive vigorous fluid resuscitation.

• Journal of Korean Neurosurgical Society
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• v.64 no.1
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• pp.110-119
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• 2021

Objective : Preoperative prediction of the arachnoid membrane descent in pituitary surgery is useful for achieving gross total removal and avoiding cerebrospinal fluid leakage resulting from tearing of the arachnoid membrane in the chiasmatic cistern. In this study, we analyzed the patterns of arachnoid membrane descent during or after pituitary tumor surgery and identified the factors related to this descent. Methods : Analysis was restricted to pituitary macroadenomas not extending into the third ventricle or over the internal carotid artery. To minimize confounding factors, patients who underwent revision surgery, those who had a torn arachnoid during operation or small medial diaphragma sellae (DS) opening, and subtotal resections were excluded. We enrolled 41 consecutive patients in this retrospective analysis. The degree of arachnoid descent was categorized using intraoperative videos. Preoperative magnetic resonance findings, including tumor height, suprasellar extension, and variables including DS area and medial opening size, tumor composition, and displacement of the pituitary stalk and gland were evaluated to determine their correlations with arachnoid membrane descent. Results : Arachnoid membrane descent was significantly correlated with DS area and medial opening size. Based on T2-weighted images (T2WI) magnetic resonance (MR) images, tumor composition was significantly associated with arachnoid membrane descent. Other factors were not significantly correlated with arachnoid membrane descent. Conclusion : T2WI of tumor composition and preoperative MR imaging of DS area and medial opening provided valuable information regarding arachnoid membrane descent. These parameters may serve as fundamental measures to facilitate complete resection of pituitary macroadenomas.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.51-61
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• 2021

In the era of the 4th industrial revolution symbolized by the Internet of Things, big data and artificial intelligence, various embedded devices are increasing exponentially. These devices have communication functions despite their low specifications, so the possibility of personal information leakage is increasing, and security threats are also increasing. Embedded devices can have security issues at most levels, from hardware to services over the network. In addition, it is difficult to apply general security techniques because it has characteristics of resource constraints such as low specifications and low power, and the related technology has not been standardized. In this study, we present vulnerabilities and possible problems and considerations in applying SDN to embedded devices in consideration of structural characteristics and real-world discovered cases. This study presents vulnerabilities and possible problems and considerations when applying SDN to embedded devices. From a hardware perspective, we consider the problems of Wi-Fi chips and Bluetooth, the problems of open flow implementation, SDN controllers, and examples of structural properties. SDN separates the data plane and the control plane, and provides a standardized interface between the two, enabling efficient communication control. It can respond to the security limitations of existing network technologies that are difficult to respond to rapid changes.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.12
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• pp.321-332
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• 2020

Decentralized approaches are extensively researched by academia and industry in order to cover up the flaws of existing systems in terms of data privacy. Blockchain and decentralized learning are prominent representatives of a deconcentrated approach. Blockchain is secure by design since the data record is irrevocable, tamper-resistant, consensus-based decision making, and inexpensive of overall transactions. On the other hand, decentralized learning empowers a number of devices collectively in improving a deep learning model without exposing the dataset publicly. To motivate participants to use their resources in building models, a decent and proportional incentive system is a necessity. A centralized incentive mechanism is likely inconvenient to be adopted in decentralized learning since it relies on the middleman that still suffers from bottleneck issues. Therefore, we design an incentive model for decentralized learning applications by leveraging the Ethereum smart contract. The simulation results satisfy the design goals. We also outline the concerns in implementing the presented scheme for sensitive data regarding privacy and data leakage.

• Journal of Trauma and Injury
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• v.34 no.1
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• pp.39-43
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• 2021

Purpose: Determining appropriate ways to assess health care quality within the National Health Insurance System is of interest to both the Korean government and the medical community. However, in the trauma field, the number of indicators used to evaluate surgical quality is limited. Using data collected over 5 years at Wonju Severance Christian Hospital Trauma Center in Korea, this study aimed to determine whether the unplanned reoperation rate in the field of trauma surgery could be used to assess the quality of an institution's surgical care. Methods: In total, 665 general surgical procedures were performed at the Trauma Center in 453 patients with abdominopelvic injuries from January 2015 to December 2019. Data were collected from the Trauma Center's data registry and medical records, and included information regarding patients' demographic characteristics, the type of index operation, and the reason for unplanned reoperations. Results: A total of 453 index operations were evaluated. The proportion of patients with an Injury Severity Score (ISS) >15 was 48-70% over the 5-year period, with an unplanned reoperation rate of 2.1-9.3%. Patients had an average ISS score of 17.5, while the average Abbreviated Injury Scale Score was 2.87. Unplanned reoperations were required in about 7% of patients. The most common complications requiring reoperation were recurrent bleeding (26.9%), wound problems (26.9%), intestinal infarction (15.4%), and anastomosis site leakage (7.7%). The procedures most frequently requiring unplanned reoperations were bowel surgery (segmental resection, primary repair, enterostomy, etc.) (24.5%) and preperitoneal pelvic packing (10.6%). Conclusions: The proportion of reoperations was confirmed to be affected by injury severity.

• Convergence Security Journal
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• v.20 no.4
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• pp.169-176
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• 2020

Recently, the era in which various services using smart devices are used is sometimes referred to as the so-called "smart era". Among these, Smart Home Service' have not only brought about significant changes in the residential environment and culture, but are evolving very rapidly. and The 'Smart Home Service' provides more convenient services to users through communication between various electronic products in general homes, and has a bright future in the future. In particular,'Smart Home Service' provides various services combined based on IoT(Internet of Things) technology and wired/wireless communication in connection between various devices. However, such a "smart home service" inherits the security vulnerabilities of the underlying technologies such as the Internet of Things and wired and wireless communication technologies, and accidents that lead to the leakage of personal information and invasion of privacy continue to occur. So, it is necessary to prepare a countermeasure and prevention against the weak factors of the underlying technologies. Therefore, this paper is expected to be used as basic data for future application technology development and countermeasure technology by examining various security vulnerability factors of 'Smart Home Service'.

• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.1-6
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• 2021

In this study, we developed AMI terminals of 1 (reader): N (small transmitter). Currently, the government is focusing on the Gas AMI demonstration project to advance the outdated metering system of the urban gas industry, led by the government-sponsored ministries. The supply of gas AMI meters has the advantage of resolving uncertainties in privacy violations and measurement information and preparing for consumer safety through gas leakage detection. In the case of existing AMI meters, readers and transmitters were 1:1 methods, while this technology can be extended to multiple generations with a 1:N method, and a technology that can extend battery life by implementing a low-power design is applied. We hope that this research will contribute to the gas AMI supply project in the future.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.790-798
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• 2008

Counter-rotating axial flow fan(CRF) consists of two counter-rotating rotors without stator blades. CRF shows the complex flow characteristics of the three-dimensional, viscous, and unsteady flow fields. For the understanding of the entire core flow in CRF, it is necessary to investigate the three-dimensional unsteady flow field between the rotors. This information is also essential to improve the aerodynamic characteristics and to reduce the aerodynamic noise level and vibration characteristics of the CRF. In this paper, experimental study on the three-dimensional unsteady flow of the CRF is performed at the design point(operating point). Flow fields in the CRF are measured at the cross-sectional planes of the upstream and downstream of each rotor using the $45^{\circ}$ inclined hot-wire. The phase-locked averaged hot-wire technique utilizes the inclined hot-wire, which rotates successively with 120 degree increments about its own axis. Three-dimensional unsteady flow characteristics such as tip vortex, secondary flow and tip leakage flow in the CRF are shown in the form of the axial, radial and tangential velocity vector plot and velocity contour. The phase-locked averaged velocity profiles of the CRF are analyzed by means of the stationary unsteady measurement technique. At the mean radius of the front rotor inlet and the outlet, the phase-locked averaged velocity profiles show more the periodical flow characteristics than those of the hub region. At the tip region of the CRF, the axial velocity is decreased due to the boundary layer effect of the fan casing and the tip vortex flow. The radial and the tangential velocity profiles show the most unstable and unsteady flow characteristics compared with other position of rotors. But, the phase-locked averaged velocity profiles of the downstream of the rear rotor show the aperiodic flow pattern due to the mixture of the front rotor wake period and the rear rotor rotational period.