• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.6
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• pp.802-808
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• 2020

The IoT(Internet of Things) is based on the development of sensor technology and high-speed communication infrastructure, and the number of IoT connected to the network is increasing more than the number of people, and the increase is also very fast. In the field of defense, IoT is being deployed in various fields such as operations, military, base defense, and informatization, and the need is also increasing. Unlike the existing PC/server information protection system, cyber threats are also increasing as IoT sensors, which are vulnerable to information protection, are increasing in the network, so it is necessary to study the platform to protect the defense information and communication network. we investigated the case of connecting wired and wireless IoT to the defense network, and presented an efficient interlocking design method of the IoT integrated independent network with enhanced security by minimizing the contact point with the defense network.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.1-8
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• 2023

Power transmission shafts in rotary wing aircraft use a hollow shaft to reduce weight. We can apply linear elastic fracture mechanics to predict crack propagation behavior. This paper predicted crack growth life of a hollow shaft with a circumferential through-type crack by finite element analysis. A 2D finite element model was created by applying a torsion and forming elements considering cracks. We defined the initial crack length and performed the finite element analysis by increasing the crack length to derive stress intensity factor at crack tips. We defined the length just prior to the stress intensity factor exceeding the fracture toughness as the crack limit length. We calculated the crack limit length using a handbook and numerically integrated the crack growth rate equation to derive growth life of each crack. The growth life of each crack was compared to verify the proposed finite element analysis method.

• Composites Research
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• v.32 no.1
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• pp.65-70
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• 2019

The aircraft composites wing parts are usually integrated with adhesive or fastener. These laminated composites have weak interlaminar strength, which can lead to delamination. In order to compensate the disadvantages of laminated composites, it is possible to improve the strength, durability, shock and fatigue resistance by reinforcing the fiber in the thickness direction. In addition, using a single structure near-net-shape saves the manufacturing time and the number of fasteners, thus can reduce the overall cost of the composite parts. In this study, compression test, tensile test and open-hole tensile test are carried out for three structural architecture of 3D (three-dimensional) textile preforms: orthogonal(ORT), layer-to-layer(LTL) and through-the-thickness(TTT) patterns. Among these, the orthogonal textile composite shows the highest Young's modulus and strength in tensile and compression. The notch sensitivity of the orthogonal textile composite was the smallest as compared with UD (unidirectional) and 2D (two-dimensional) fabric laminates.

• The Journal of Internal Korean Medicine
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• v.41 no.6
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• pp.1245-1254
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• 2020

Introduction: The aim of this study was to report the effect of Korean medicine treatments on a stroke patient with acute cerebral infarction. Method: A 63-year-old male with anterior and middle cerebral artery infarction had symptoms of dizziness and disorientation. The patient was treated with Korean medicine therapy, including the herbal medicine "Sunghyuangjunggi-san-gamibang." Treatment progress was assessed using the Korean version of the Modified Barthel Index (K-MBI) and the Korean dizziness handicap inventory (K-DHI). Results: After 14 days of treatment, the K-DHI score decreased from 78 to 7 and the K-MBI score increased from 18 to 24. The patient's main symptoms were improved after the treatment, and no side effects were observed. Conclusion: Korean medicine treatment, including Sunghyuangjunggi-san, might be a recommended therapeutic option for dizziness and disorientation in stroke patients.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.172-178
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• 2021

In the ship repair market, interest in maintenance and repair is steadily increasing due to the reinforcement of prevention of environmental pollution caused by ships and the reinforcement of safety standards for ship structures. By reflecting this effect, the number of requests for repairs by foreign shipping companies increases to repair shipbuilders in the Southwest Sea. However, because most of the repair shipbuilders in the southwestern area are small and medium-sized companies, it is difficult to lead to the integrated synergy effect of the repair shipbuilding companies. Moreover, the infrastructure is not integrated; hence, using the infrastructure jointly is a challenge, which acts as an obstacle to the activation of the repair shipbuilding industry. Floating docks are indispensable to operating the repair shipbuilding business; in addition, most of them are operated through renovation/repair after importing aging caisson docks from overseas. However, their service life is more than 30 years; additionally, there is no structure inspection standard. Therefore, it is vulnerable to the safety field. In this study, the finite element analysis program of ANSYS was used to evaluate the structural safety of the modified caisson dock and obtain additional structural reinforcement schemes to solve the derived problems. For the floating docks, there are classification regulations; however, concerning structural strength, the regulations are insufficient, and the applicability is inferior. These insufficient evaluation areas were supplemented through a detailed structural FE-analysis. The reinforcement plan was decided by reinforcing the pontoon deck and reinforcement of the side tank, considering the characteristics of the repair shipyard condition. The final plan was selected to reinforce the side wing tank through the structural analysis of the decision; in addition, the actual structure was fabricated to reflect the reinforcement plan. Our results can be used as reference data for improving the structural strength of similar facilities; we believe that the optimal solution can be found quickly if this method is used during renovation/repair.