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A Derivation of Potential Korean Exports to Africa
김흥종,Youngho Park 대외경제정책연구원 2002 East Asian Economic Review Vol.6 No.2
The aim of the paper is to derive potential Korean exports to major African countries. Park (2001) adopted conventional RCA and MCA techniques to evaluate the relative performance of Korean exports to draw up a list of recommendable exports to Africa. We improve Park's results in two ways; first, we develop a new indicator reflecting the characteristics of the African market, which was ignored in the former analysis, and second, we derive the RCA and MCA values of Chinese and Japanese exports to Africa and compare them with those of Korean products. The final list of Korea's potential exports to the African market is carefully derived and we find that competing with Japanese exports rather than Chinese ones is a more appropriate strategy for amending Korea's record of underperforming exports to Africa.
Kwon, Soon Jik,Kim, Tae Geun,Park, Youngjun,Kwon, Ohseok,Cho, Youngho The Ecological Society of Korea 2015 Journal of Ecology and Environment Vol.38 No.4
This study was performed to provide important basic data for the preservation and management of Scopura laminata, a species endemic to Korea, by elucidating the spatial characteristics of its present, potential, and future distribution areas. Currently, this species is found in the Odaesan National Park area of South Korea and has been known to be restricted in its habitat due to its poor mobility, as even fully grown insects do not have wings. Utilizing the MaxEnt model, 20 collection points around Odaesan National Park were assessed to analyze and predict spatial distribution characteristics. The precision of the MaxEnt model was excellent, with an AUC value of 0.833. Variables affecting the potential distribution area of S. laminata by more than 10% included the range of annual temperature, seasonality of precipitation, and precipitation of the driest quarter, in order of greatest to least impact. Compared to the current potential distribution area, no significant difference in the overall habitable area was predicted for the 2050s or 2070s. It was, however, demonstrated that the potential habitable area would be reduced in the 2050s by up to 270.3 km from the current area of 403.9 km; further, no potential habitable area was anticipated by the 2070s according to our predictive model. Taken together, it is anticipated that this endemic species could be significantly affected by climate changes, and hence effective countermeasures are strongly warranted for the preservation of habitats and species management.
A Secure Incentive Scheme for Vehicular Delay Tolerant Networks Using Cryptocurrency
Park, Youngho,Sur, Chul,Rhee, Kyung-Hyune Hindawi Limited 2018 Security and communication networks Vol.2018 No.-
<P>One remarkable feature of vehicular ad hoc networks is characterized by an opportunistic communications by means of store-carry-forward message relaying which requires the cooperation of vehicles on the networks. However, we cannot be sure that all vehicles willingly contribute their computing resources to the networks for message forwarding with no rewards for their efforts in real-world scenarios. In addition, unfortunately, there may exist some selfish and greedy node which may not help others but tend to take their own gain. To cope with this challenge, incentive mechanisms are generally considered as the promising solution. In this paper, we design a Bitcoin-based secure and reliable incentive scheme for cooperative vehicular delay tolerant networking services. Bitcoin is the well-known worldwide cryptocurrency and digital payment system whose implementation relies on cryptographic techniques, which makes it possible to develop a practical credit-based incentive scheme on the vehicular networks at a low cost. We also implement Bitcoin transaction scripts to handle our proposed incentive scheme.</P>
Secure and Scalable Key Aggregation Scheme for Cloud Storage
Park, YoHan,Park, YoungHo Korea Society of Industrial Information Systems 2015 한국산업정보학회논문지 Vol.20 No.2
As the communication technology and mobile devices develop, the need for the efficient and secure remote storage is required. And recently, many companies support cloud storages to meet the requirements of the customers. Especially in the business field where various companies collaborate, data sharing is an essential functionality to enhance their work performance. However, existing researches have not fully satisfied the requirement either efficiency and security. This paper suggests efficient and secure data sharing scheme for cloud storage by using secret sharing scheme. Proposed scheme can be applied to business collaborations and team projects.
A SECURE DYNAMIC SOURCE ROUTING PROTOCOL CONCURRENT WITH KEY EXCHANGE
Youngho Park,Kyung-Hyune Rhee 한국멀티미디어학회 2006 한국멀티미디어학회 국제학술대회 Vol.2006 No.-
Ad hoc routing is a very fundamental operation of ad hoc network management, and hence it has been a main target of an attacker to disrupt an ad hoc network. Therefore, not only secure communication among nodes but also exchanging some special messages for the purpose of security operations, such as key distribution in ad hoc networks, cannot help relying on secure routing protocol. In this paper, we raise a question about key management for existing secure routing protocols and, as one solution to this question, we propose a secure ad hoc routing protocol concurrent with key exchange using ID-based public keys. We focus on providing authentication mechanism to Dynamic Source Routing protocol combined with Diffie-Hellman key exchange. The main advantage of the proposed protocol is that establishing a route and a session key between the source and the destination node can be performed at the same time in a secure manner during the routing discovery protocol.
Secure Private Key Revocation Scheme in Anonymous Cluster -Based MANETs
Park, YoHan,Park, YoungHo Korea Multimedia Society 2015 멀티미디어학회논문지 Vol.18 No.4
Security supports are a significant factor in the design of mobile ad hoc networks. In the dynamic topology where the node changes frequently, private key generation and revocation for newly joining and leaving nodes must be considered. In addition, the identities of individual nodes must be protected as well in mobile networks to avoid personal privacy concerns. This paper proposes ID-based private key revocation scheme and non-interactive key agreement scheme in anonymous MANETs. The proposed scheme provides the user privacy using pseudonyms and private key generation and revocation schemes with consideration of dynamic user changes. Therefore, our schemes can be applied in dynamic and privacy-preserving MANETs which are helpful to share multimedia data.
Effects of Grain Size Distribution on the Mechanical Properties of Polycrystalline Graphene
Park, Youngho,Hyun, Sangil The Korean Ceramic Society 2017 한국세라믹학회지 Vol.54 No.6
One of the characteristics of polycrystalline graphene that determines its material properties is grain size. Mechanical properties such as Young's modulus, yield strain and tensile strength depend on the grain size and show a reverse Hall-Petch effect at small grain size limit for some properties under certain conditions. While there is agreement on the grain size effect for Young's modulus and yield strain, certain MD simulations have led to disagreement for tensile strength. Song et al. showed a decreasing behavior for tensile strength, that is, a pseudo Hall-Petch effect for the small grain size domain up to 5 nm. On the other hand, Sha et al. showed an increasing behavior, a reverse Hall-Petch effect, for grain size domain up to 10 nm. Mortazavi et al. also showed results similar to those of Sha et al. We suspect that the main difference of these two inconsistent results is due to the different modeling. The modeling of polycrystalline graphene with regular size and (hexagonal) shape shows the pseudo Hall-Petch effect, while the modeling with random size and shape shows the reverse Hall-Petch effect. Therefore, this study is conducted to confirm that different modeling is the main reason for the different behavior of tensile strength of the polycrystalline structures. We conducted MD simulations with models derived from the Voronoi tessellation for two types of grain size distributions. One type is grains of relatively similar sizes; the other is grains of random sizes. We found that the pseudo Hall-Petch effect and the reverse Hall-Petch effect of tensile strength were consistently shown for the two different models. We suspect that this result comes from the different crack paths, which are related to the grain patterns in the models.