• 화훼연구
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• 제19권1호
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• pp.1-7
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• 2011

본 연구는 나리 하계 고온기 고품질 절화생산 및 경영비 절감을 위한 도입 소구의 비대증식에 유리한 환경조건을 찾아내기 위해 수행하였다. 종구비 절감을 위해 소구를 도입하여 양구하는데 효과적인 환경조건을 찾아내고자 재배형태를 비가림, 망실, 무피복으로 나누고 다시 절화 재배시 많이 사용하는 30% 차광처리와 무처리로 구분하여 시험하였다. 모든 처리구에서 비가림 재배가 우수하였고 차광의 효과도 다소 있었다. 특히 양구에 있어서는 대관령 등의 고랭지에서 주간과 야간온도의 차이가 커서 동화산물의 전류 및 축적이 많아 평지에 비해 구비대가 유리하여 시비 및 관수방법에 따라 보통 3년 정도인 양구 기간을 단축할 수도 있을 것으로 기대된다.

• 비교문화연구
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• 제48권
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• pp.253-287
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• 2017

이 글의 목적은 본 연구자가 에티오피아 아셀라 타운에서의 현지조사를 통해 수집한 자료를 토대로, 종족 현상을 다층적 맥락에서 살펴보는 데 있다. 생태학적 조건, 양대 종족의 숫자상 균형, 빈번한 종족 외혼 및 '젖 먹이기'라는 사회문화적 관행의 영향 등으로 인해, 이 타운에서는 집단적 수준의 종족 갈등이 거의 발생하지 않았다. 하지만 이러한 관행의 긍정적인 영향에도 불구하고, 아셀라에서는 지배 종족에 의한 차별과 위협이 지속적으로 발생해 온 것으로 파악되었다. 대개의 제보자는 종족 외혼이 종족 집단 및 공동체 구성원의 유대를 강화하고, 상이한 종족 문화를 습득하고, 사람들 간의 관용 정신을 배양하고, 혼종적(다중적) 종족 정체성을 가진 우수한 2세를 생산하는 데 기여한다고 여기고 있었다. 그러나 일부 제보자는 종족 외혼이 그 당사자의 이기적인 선택에 불과할 뿐만 아니라 종족 정체성을 손상시키므로, 결코 바람직한 일이 아니라는 입장을 견지했다. 상당수의 제보자는 현재 진행 중인 오로모화가 지극히 당연한 현상이라 여기고 있는 반면, 일부 제보자는 오로모화를 강제성, 피상성 및 생존 전략의 맥락에서 파악될 필요가 있다고 역설했다.

• 국제지역연구
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• 제13권3호
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• pp.551-581
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• 2009

이 연구는 중국의 공항 중 인천의 허브화 전략의 경쟁공항인 베이징공항(수도), 상하이공항(푸동)을 대상으로 지분매각, 지배구조, 공항운영 및 시설확충 등에 관한 사례를 분석한다. 세계 주요공항의 전략적 허브화 경쟁이 가속화되면서, 인천공항은 급변하는 경영환경에 대처하고 무한경쟁에서 생존하기 위하여 경영 패러다임의 전환이 시급하다. 그 일환으로 공항에 대한 대내외적 혁신요구에 적극 대응하는 새로운 소유구조와 지배구조 및 운영효율화 방안을 모색하여야 한다. 공항의 일반적인 민영화 방안에는 기업거래(trade sale), 기업공개(IPO), 영업허가, 경영위탁, 프로젝트 파이낸싱의 5가지가 있다. 세계 공항산업의 동향과 함께 중국의 경쟁공항의 민영화와 관련하여 지분매각 및 이후의 지배구조에 초점을 맞추어 인천공항의 일부 지분매각과 지배구조, 공항개발 및 운영 등의 주요 의사결정에 대한 시사점을 도출한다. 인천공항이 동북아허브로서 성장하기 위해서는 공항시설 확충을 위한 재원을 조달하여야 하며, 운영 효율성의 강화가 필요하다. 공공성의 보장을 위해 공기업 형태를 유지하되, 민영화의 장점을 살리기 위해, 정부가 51% 이상의 지분을 보유하는 부분 민영화를 하되, 기업 가치를 극대화하기 위해 기업거래와 기업공개를 함께 활용하되 전략적으로 그 속도와 시기를 결정하여야 한다.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.541-547
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• 2019

최근 자동화 되는 해킹 및 분석 기술의 발전으로 인하여 수많은 소프트웨어 보안 취약점이 빠르게 발표되고 있다. 대표적인 취약점 데이터베이스인 NVD(National Vulnerability Database)에는 2010년부터 2015년까지 보안 취약점(CVE: Common Vulnerability Enumeration) 약 8만 건이 등록되었으며, 최근에도 점차 증가하고 있는 추세이다. 보안 취약점은 빠른 속도로 증가하고 있는 반면, 보안 취약점을 분석하고 대응하는 방법은 전문가의 수동 분석에 의존하고 있어 대응 속도가 느리다. 이런 문제점을 해결하기 위해 자동화된 방법으로 보안 취약점을 탐색하고, 패치하여 악의적인 공격자에게 공격 기회를 줄 수 있는 보안 취약점을 사전에 대응 할 수 있는 기술이 필요하다. 본 논문에서는 복잡도 분석을 통해 취약점 탐색 대상 바이너리의 특징을 추출하고, 특징에 적합한 취약점 탐색 전략을 선정하여 취약점을 자동으로 탐색하는 기술을 제안한다. 제안 기술은 AFL, ANGR, Driller 도구와 비교 검증 하였으며 코드 커버리지는 약 6% 향상, 크래시 개수는 약 2.4배 증가, 크래시 발생율 약 11% 향상 효과를 볼 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권6호
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• pp.874-880
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• 2019

Objective: Ozone is considered a strong antimicrobial agent with numerous potential applications in the food industry. However, its high oxidizing potential can induce alterations in foods by acting on the unsaturated fatty acids. The aim of this study was to investigate the effect of ozonation on the oxidative stability of chicken breast meat obtained from animals subjected to different feeding strategies. Methods: Samples were obtained from commercial hybrid chickens (ROSS 508), some of which were nourished with a feed enriched with fats of animal origin, while the lipid source was vegetal for the remaining birds. Samples of meat belonging to both groups were treated with ozone and then analysis was performed to evaluate alterations in physical properties, lipid content, fatty acid profile, and oxidation stability. Results: Ozone induced a significant reduction in drip loss in meat samples obtained from animals nourished with vegetable fats; this nutritional strategy also produced meats leaner and richer in polyunsaturated fatty acids. Thiobarbituric acid reactive substances, useful for the assessment of lipid oxidation, were higher in samples obtained from animals fed with vegetable fats with respect to diet based on the addition of animal fats. Conclusion: The ozone treatment improved the physical parameters of meat samples obtained from animals fed with vegetable fats, however the same samples showed a higher lipid oxidation compared to what observed in the case of the dietary intake of animal fats, probably as a consequence of the marked increase in polyunsaturated fatty acids which are more susceptible to peroxidation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2496-2512
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• 2021

The requirements for powerful computing capability, high capacity, low latency and low energy consumption of emerging services, pose severe challenges to the fifth-generation (5G) network. As a promising paradigm, mobile edge networks can provide services in proximity to users by deploying computing components and cache at the edge, which can effectively decrease service delay. However, the coexistence of heterogeneous services and the sharing of limited resources lead to the competition between various services for multiple resources. This paper considers two typical heterogeneous services: computing services and content delivery services, in order to properly configure resources, it is crucial to develop an effective offloading and caching strategies. Considering the high energy consumption of 5G base stations, this paper considers the hybrid energy supply model of traditional power grid and green energy. Therefore, it is necessary to design a reasonable association mechanism which can allocate more service load to base stations rich in green energy to improve the utilization of green energy. This paper formed the joint optimization problem of computing offloading, caching and resource allocation for heterogeneous services with the objective of minimizing the on-grid power consumption under the constraints of limited resources and QoS guarantee. Since the joint optimization problem is a mixed integer nonlinear programming problem that is impossible to solve, this paper uses deep reinforcement learning method to learn the optimal strategy through a lot of training. Extensive simulation experiments show that compared with other schemes, the proposed scheme can allocate resources to heterogeneous service according to the green energy distribution which can effectively reduce the traditional energy consumption.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.148-163
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• 2021

Timely fault identification is important for safe and reliable operation of the electric valve system. Many research works have utilized different data-driven approach for fault diagnosis in complex systems. However, they do not consider specific characteristics of critical control components such as electric valves. This work presents an integrated shallow-deep fault diagnostic model, developed based on signals extracted from DN50 electric valve. First, the local optimal issue of particle swarm optimization algorithm is solved by optimizing the weight search capability, the particle speed, and position update strategy. Then, to develop a shallow diagnostic model, the modified particle swarm algorithm is combined with support vector machine to form a hybrid improved particle swarm-support vector machine (IPs-SVM). To decouple the influence of the background noise, the wavelet packet transform method is used to reconstruct the vibration signal. Thereafter, the IPs-SVM is used to classify phase imbalance and damaged valve faults, and the performance was evaluated against other models developed using the conventional SVM and particle swarm optimized SVM. Secondly, three different deep belief network (DBN) models are developed, using different acoustic signal structures: raw signal, wavelet transformed signal and time-series (sequential) signal. The models are developed to estimate internal leakage sizes in the electric valve. The predictive performance of the DBN and the evaluation results of the proposed IPs-SVM are also presented in this paper.

• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.37-44
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• 2022

Plug-in Hybrid electric vehicles (PHEV) show great potential to reduce gas emission, improve fuel efficiency and offer more driving range flexibility. Moreover, PHEV help to preserve the eco-system, climate changes and reduce the high demand for fossil fuels. To address this; some basic components and energy resources have been used, such as batteries and proton exchange membrane (PEM) fuel cells (FCs). However, the FC remains unsatisfactory in terms of power density and response. In light of the above, an electric storage system (ESS) seems to be a promising solution to resolve this issue, especially when it comes to the transient phase. In addition to the FC, a storage system made-up of an ultra-battery UB is proposed within this paper. The association of the FC and the UB lead to the so-called Fuel Cell Battery Electric Vehicle (FCBEV). The energy consumption model of a FCBEV has been built considering the power losses of the fuel cell, electric motor, the state of charge (SOC) of the battery, and brakes. To do so, the implementing a reinforcement-learning energy management strategy (EMS) has been carried out and the fuel cell efficiency has been optimized while minimizing the hydrogen fuel consummation per 100km. Within this paper the adopted approach over numerous driving cycles of the FCBEV has shown promising results.

• Wind and Structures
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• 제35권4호
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• pp.269-285
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• 2022

The pressure-mitigating effects of a high-speed train passing through a tunnel with a partially reduced cross-section are investigated via the numerical approach. A compressible, three-dimensional RNG k-ε turbulence model and a hybrid mesh strategy are adopted to reproduce that event, which is validated by the moving model test. Three step-like tunnel forms and two additional transitions at the tunnel junction are proposed and their aerodynamic performance is compared and scrutinized with a constant cross-sectional tunnel as the benchmark. The results show that the tunnel step is unrelated to the pressure mitigation effects since the case of a double-step tunnel has no advantage in comparison to a single-step tunnel, but the excavated volume is an essential matter. The pressure peaks are reduced at different levels along with the increase of the excavated earth volume and the peaks are either fitted with power or logarithmic function relationships. In addition, the Arc and Oblique-transitions have very limited gaps, and their pressure curves are identical to each other, whereas the Rec-transition leads to relatively lower pressure peaks in C_Pmax, C_Pmin, and ΔC_P, with 5.2%, 4.0%, and 4.1% relieved compared with Oblique-transition. This study could provide guidance for the design of the novel railway tunnel.

• Journal of Korea Trade
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• 제26권3호
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• pp.23-44
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• 2022

Purpose - Recent issues such as vessel enlargement, strengthening of environmental regulations, and port smartization are expected to increase costs and intensify competition in the port industry. In the new normal era, when external growth has reached its limit, the efficient operation of ports is becoming indispensable for achieving sustainable growth. This study aims to identify the determinants of inefficiency by examining the cost structure and efficiency of container terminals in Korea and furthermore propose the political implications to derive the maximization of efficiency. Design/methodology - This study estimates the cost function of container terminal operators and identifies the efficiency of container terminals using stochastic cost frontier (SCF) in the first stage. In the second step, the SCF results are compared with the data envelopment analysis (DEA). Last, this paper proposes efficiency determinants on container terminal operation to establish appropriate strategies. Out of the 29 container terminal operators in South Korea, 13 operators participated in the survey. The translog cost function was estimated utilizing a total of 116 observations collected over the 2007-2017 period. Findings - Empirical analysis shows that economies of scale exist in Korea's container ports, which provides a rationale for the government's policy to establish the global terminal operator by integrating small terminal operators to enhance competitiveness. In addition, as a result of the determinants analysis, container throughput, weight of direct employment costs, and labour cost share have positive effects on improving cost efficiency, while inefficiency increases as the length of quay increases. More specifically, cost efficiency improves as the proportion of direct employment costs to outsourcing service costs increases. Originality/value - This study contributes to analyzing the inefficiency factors of container terminals through efficiency analysis with respect to a cost function. In addition, this study proposes the practical and political implications, such as establishing a long-term manpower pool, the application of the hybrid liner terminal system, and the construction of a statistical data system, to improve the cost inefficiency of terminal operators.