• 한국농촌건축학회논문집
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• 제22권2호
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• pp.26-34
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• 2020

This study is to find a way that improves the pedestrian environment in the main street in rural areas. The main streets of five local governments in Jeollanam-do, general towns and bases seat of a myeon office, were studied. The research results are as follows. First, all three groups under investigation required multi-purpose activities on main street. This is thought to be due to the maintenance of the main street with vehicle-centered maintenance, thereby revising the walking space around essential activities. Second, the simple size of the sidewalk width is not closely related to the safety of pedestrians, and it is judged that the pedestrian space should be maintained considering the size of the floating population, acceptable activities, and proper sidewalk width. Third, the center where pedestrian space and streetscape are maintained has spatial constraints on sidewalks and lanes, so there should be spatial flexibility. Also, it is necessary to find a way to minimize the occupancy of pedestrian roads due to ground parking lots in relation to pedestrian continuity. Fourth, improvement of walking environment should involve community activities other than physical improvement.

• 대한전기학회논문지:전력기술부문A
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• 제49권4호
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• pp.161-167
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• 2000

This paper presents a new methodology that can evaluate transfer capability of composite power systems from the adequacy point of view in power system planning stages. First of all, to evaluate practical load supplying capability, nonlinear optimization problems of maximum load supplying capability(MLSC) and economic load supplying capability(ELSC) are formulated and solved by nonlinear primal-dual interior point method. Here, physical constraints considered in the optimization problems are the limits of bus voltage, line overloading, and real & reactive power generation. Also, an evaluation method of transfer capability is presented based on margins calculated by the MLSC and ELSC. Especially, to evaluate transfer capability flexibly, simple indices such as expected MLSC, transfer capability margin, and power not supplied are respectively proposed by considering (N-1) line outage probability. Numerical results on IEEE RTS 24, IEEE 118, and IEEE 300 bus system show that the proposed algorithm is effective and useful for power system planning stages.

• 천문학논총
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• 제30권2호
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• pp.99-101
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• 2015

Massive stars are some of the most influential objects in the Universe, shaping the evolution of galaxies, creating chemical elements and hence shaping the evolution of the Universe. However, the processes by which they form and how they shape their environment during their birth processes are not well understood. We use $NH_3$ data from "The $H_2O$ Southern Galactic Plane Survey" (HOPS) survey to define the positions of dense cores/clumps of gas in the southern Galactic plane that are likely to form stars. Then, using data from "The Millimetre Astronomy Legacy Team 90 GHz" (MALT90) survey, we search for the presence of infall and outflow associated with these cores. We subsequently use the "3D Molecular Line Radiative Transfer Code" (MOLLIE) to constrain properties of the infall and outflow, such as velocity and mass flow. The aim of the project is to determine how common infall and outflow are in star forming cores, and therefore to provide valuable constraints on the timescales and physical process involved in massive star formation. Preliminary results are presented here.

• 천문학논총
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• 제30권2호
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• pp.113-114
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• 2015

Recent high-resolution, high-sensitivity observations of protostellar jets have shown many to possess an underlying 'wiggle' structure. HH 211 is one such example where recent sub-mm observations revealed a clear reflection-symmetric wiggle. An explanation for this is that the HH211 jet source is moving as part of a protobinary system. Here we test this assumption by simulating HH211 through 3D hydrodynamic simulations using the pluto code with a molecular chemistry and cooling module, and initial conditions based on an analytical model derived from SMA observations. Molecular chemistry allows us to accurately plot synthetic molecular emission maps and position-velocity diagrams for direct comparison to observations, enabling us to test the observational assumptions and put constraints on the physical parameters of HH211. Our preliminary results show that the reflection-symmetric wiggle can be recreated through the assumption of a jet source being part of a binary system.

• 천문학논총
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• 제30권2호
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• pp.633-636
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• 2015

KaVA (KVN and VERA Array) is a new combined VLBI array composed of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). Here, we report the following two issues. (1) We review the initial results of imaging observations of M87 at 23 GHz following Niinuma et al. (2014). The KaVA images reveal extended outflows including complex substructures such as knots and limb-brightening, in agreement with previous VLBI observations. KaVA achieves a high dynamic range of ~1000, more than three times better than that achieved by VERA alone. (2) Based on subsequent observations and discussions led by the KaVA AGN SubWorking Group, we set monitoring observations of Sgr $A^{\ast}$ and M87 as our Key Science Project (hereafter KSP) because of the closeness and largeness of their central super-massive black holes. The main science goals of the KSP are (i) testing the magnetically-driven-jet paradigm by mapping velocity fields of the M87 jet, and (ii) obtaining tight constraints on physical properties of the radio emitting region in Sgr $A^{\ast}$. Towards KSP, we show the first preliminary images of M87 at 23 GHz and Sgr $A^{\ast}$ at 43 GHz with the bandwidth of 256 MHz.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.445-452
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• 2002

In the field of civil and geotechnical engineering, students conduct a variety of soil tests to fulfill undergraduate soil mechanics course requirement. There is a range of problems in soil laboratory instruction, such as, some students not getting hands on experience of conducting tests because of inadequate number of apparatus, time constraints and inability in exciting students to seriously conduit the experiments, However when these laboratory soil tests are simulated with multimedia interaction ann visualization techniques, the students conceptual understanding of soil mechanics is enhanced. The simulation program for website teaching is a computer based instructional package intended to complement, and potentially replace, some physical testing in a real soil laboratory. The overall aim of this project is to develop an experimental simulation program toward active learning and development of critical thinking skills, including data interpretation, understanding of the precesses and influential factors, and problem solving. Therefore enable students to access website to team experimental procedure at any time or place.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.2805-2826
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• 2021

In most cases, the routing policy of networks shows a preference for a static one-to-one mapping of communication pairs to routing paths, which offers adversaries a great advantage to conduct thorough reconnaissance and organize an effective attack in a stress-free manner. With the evolution of network intelligence, some flexible and adaptive routing policies have already proposed to intensify the network defender to turn the situation. Routing mutation is an effective strategy that can invalidate the unvarying nature of routing information that attackers have collected from exploiting the static configuration of the network. However, three constraints execute press on routing mutation deployment in practical: insufficient route mutation space, expensive control costs, and incompatibility. To enhance the availability of route mutation, we propose an OpenFlow-based route mutation technique called Polymorphic Path Transferring (PPT), which adopts a physical and virtual path segment mixed construction technique to enlarge the routing path space for elevating the security of communication. Based on the Markov Decision Process, with considering flows distribution in the network, the PPT adopts an evolution routing path scheduling algorithm with a segment path update strategy, which relieves the press on the overhead of control and incompatibility. Our analysis demonstrates that PPT can secure data delivery in the worst network environment while countering sophisticated attacks in an evasion-free manner (e.g., advanced persistent threat). Case study and experiment results show its effectiveness in proactively defending against targeted attacks and its advantage compared with previous route mutation methods.

• Journal of Smart Tourism
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• 제1권2호
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• pp.37-46
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• 2021

The travel-related applications on a smartphone help tourists make a reservation before their trip conveniently; use a map, direction guidance, and translation services during the travel; evaluate and recommend travel services communicating with others after their journey. This study examines the relationships among affordances and constraints provided by the mini-program, users' perceived value, and travel-related mini-program (TRMP) usage by analyzing the structural equation modeling. An online questionnaire was developed from the available scales in the published literature. A total of 651 TRMP users responded to the survey, and 448 valid responses were included for analysis. Affordance, including physical, cognitive, sensory, and functional affordance, significantly influenced the hedonic value of TRMP; utilitarian value except for cognitive affordance. There were negative relationships between unfamiliarity and both types of value. The utilitarian and hedonic value of TRMP significantly influenced both the exploitative and explorative use of TRMP. Travel-related mobile applications are dramatically increased in the tourism field. This research sheds light on TRMP usage, as a new and smart device, from a user's perspective based on the affordance theory. This study represents a valuable direction regarding the emerging travel-related online platforms in tourism.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제8권1호
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• pp.9-16
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• 2019

스마트폰은 휴대용 컴퓨터로서 자리매김하고 있다. 이에 따라 가장 민감한 금융 응용 서비스조차 스마트폰을 통해 언제 어디서나 사용할 수 있게 되었다. 스마트폰은 일반 PC에 비해 무선인터넷, 이동통신망을 비롯하여 블루투스, NFC 등 근거리 통신망 등 다양한 경로를 통하여 외부와 통신하고 있으며 매우 다양한 앱이 제공되고 있어 취약점이 존재할 경우, 공격의 피해가 발생할 가능성이 높아진다. 본 논문에서는 여러 가지 물리적 제약점이 있는 스마트폰의 은행앱에서 로그인에 사용되는 동적 가상키보드의 취약점에 대하여 분석하고, 그 대응방안을 제시한다.

• Safety and Health at Work
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• 제10권2호
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• pp.188-195
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• 2019

Background: Mine workers in South Africa face challenges relating to poor health and safety, including fatigue risks, and poor socioeconomic and living conditions. Fatigue results in impaired mental and physical performance. The aim of this study was to assess contributors to fatigue of mine workers in South Africa. Methods: Data collection took place at four gold mines and one platinum mine in South Africa. A total of 21 focus groups were held with individuals in management, union representatives, and mine workers, and 564 questionnaires were completed by mine workers to gather information about fatigue and potential contributors to fatigue at these mines. Results: Qualitatively (through focus groups), fatigue was attributed to extended working hours, harsh working conditions, high workloads, production pressure, and resource constraints, along with aspects relating to demographic and socioeconomic factors, living conditions, lifestyle, health, and wellness. Greater fatigue was significantly associated with younger age, indebtedness, a lack of exercise, poor nutrition, less sleep, increased alcohol use, poor self-reported health, more sick leave, higher stress, and lower job satisfaction. Conclusion: The aim of the study was achieved; numerous work-, sociodemographic-, lifestyle-, and wellness-related factors were linked to fatigue in the participating mine workers. Contributors to fatigue should be addressed to improve health, safety, and sustainability in the industry.