PURPOSES : In this study, drone highway route alternatives were evaluated using the analytic hierarchy process (AHP) technique to investigate any difficulties or improvements while designing drone highway routes. METHODS : Based on the literature review and AHP analysis, 39 road and airport experts were surveyed to evaluate two alternate drone highway routes that connect the Seoul train station and Jamsil park near Gangnam business district. RESULTS : The AHP analysis results revealed that the environmental aspect was the most critical factor in designing a drone highway route, followed by social and technological factors. Among the investigated factors, noise and life-environment showed the highest geometric mean value of 0.21. This mean should be considered when developing plans and policies for drone highway design. CONCLUSIONS : Environmental and social agreement is more crucial than the technological and economic aspects when designing drone highway routes. Laws and policies should be updated and followed to support the drone highway system, which is vital in logistics.

In order to understand the tide and current around the sea route of Jinhae and Masan passages, tide measurement and 2D numerical model experiments of tidal current and residual flow were carried out. Tide is composed of 84% of semi-diurnal tide, 11% of diurnal tide and 4% of shallow water tide, respectively. Phase lags of the major components for the tide around the study area have little differences. The flows are reversing on the whole, but have rotational form around Jamdo Island, south of Masan passage in spring tide and Ungdo Island, north of Masan passage in middle and neap tide. Current flows the speed of 50 cm/s in the sea areas near small islands, 5 cm/s in Jinhae harbor, Hangam bay and near Jinhae industrial complex and 20-30 cm/s in Jinhae passage, Budo channel and Masan passage. Tide-induced topographical eddies are formed near small islands, but few eddies exist and the flow rate of less than 5 cm/s tidal residual current formed in Jinhae and Masan passages. The flows in Jinhae and Masan passage give a good condition for a passage into Jinhae and Masan harbor.

To meet the increased performance and cost requirements of commercial supercapacitor, a N and O self-doped hierarchical porous carbon is fabricated via a green and simple self-activation route utilizing leaves of wild hollyhock as raw materials. Comparing to commercial activated carbon, the reported material exhibits some marked merits, such as simple and green fabrication process, low cost, and superior capacitance performance. The specific surface area of the obtained N and O codoped hierarchical porous carbon arrives 954 m2 g−1, and the content of the self-doped nitrogen and oxygen reaches 2.64 at.% and 7.38 at.%, respectively. The specific capacitance of the obtained material reaches 226 F g− 1 while the specific capacitance of the symmetric supercapacitor arrives 47.3 F g− 1. Meanwhile, more than 90.3% of initial specific capacitance is kept under a current density of 20 A g− 1, and no arresting degradation is observed for capacitance after 5000 times cycle, perfectly demonstrating the excellent cycle and rate capability of the obtained material. The obtained N and O co-doped hierarchical porous carbon are expected to be an ideal substitution for commercial activated carbon.

The bone cement used for vertebroplasty must be sufficiently injectable. The introduction of granules reduces the amount of liquid required for liquefaction, implying that higher fluidity is achieved with the same amount of liquid. By employing β-tricalcium phosphate granules with an average diameter of 50 μm, changes in injectability are observed based on the paste preparation route and granular fraction. To obtain acceptable injectability, phase separation must be suppressed during injection, and sufficient capillary pressure to combine powder and liquid must work evenly throughout the paste. To achieve this, the granules should be evenly distributed. Reduced injection rates are observed for dry mixing and excessive granular content, owing to phase separation. All these correspond to conditions under which the clustered granules weakened the capillary pressure. The injected ratio of the paste formed by wet mixing displayed an inverted U-type shift with the granular fraction. The mixture of granules and powder resulted in an increase in the solid volume fraction, and a decrease in the liquid limit. This resulted in the enhancement of the liquidity, owing to the added liquid. It is inferred that the addition of granules improves the injectability, provided that the capillary pressure in the paste is maintained.

국내외적으로 유해물질의 통합 노출에 대한 관심은 높아지고 있다. 이러한 흐름에 따라 다양한 경로를 통해 노출될 수 있는 중금속에 대한 통합 노출 연구가 필요하다. 카드뮴과 납은 각각 신장 독성과 인지 장애 등 다양한 독성을 나타낼 수 있으며 또한 발암 물질로 알려져있다. 따라서 본 연구에서는 카드뮴과 납의 노출량 추정 및 통합 위해성 평가를 진행하였다. 2016, 2017년의 7기 국민건강 영양조사에 참여한 10,733명의 식품, 물, 흡연과 간접흡연, 호흡, 화장품, 여성용 위생용품을 통한 중금속 노출 추정량을 계산하였다. 결과적으로 카드뮴과 납 모두 식품을 통한 노출이 제일 높게 나타났다. 이외에도 흡연은 카드뮴의 주요한 노출원이었으며, 납은 화장품을 통해 높은 농도로 노출되었다. 통합 위해평가에서도 식품이 가장 큰 영향을 미쳤다. 지역적 특성의 차이는 노출 추정량의 차이를 보이지 못하였으나, 연령 별, 성별 간 노출 추정량은 큰 차이를 보였다. 특히, 월경 중인 성인 여성의 경우 카드뮴, 월경 중이지 않은 여성은 납의 노출 추정량이 더 높으며 신체 대사를 고려하였을 때, 그 위험성이 더 클 수 있음을 암시하였다. 결론적으로 노출량 추정 및 통합 위해평가 모두 식품이 주요 노출원이었다. 다만, 잠재적 위험을 방지하기 위해 다른 경로에 대한 노출량 추정 및 위해평가가 요구된다.

The Kra Canal is a mega-project that provide a new maritime route that would connect the Gulf of Thailand with the Andaman Sea, linking the Indian and Pacific Oceans. The idea of building the Kra Canal has widely gained attention from policy-makers, legislators, maritime activities, shipping and seaport operators due to advantages such as big cost savings, higher levels of safety and security, shortened distance and time compared to the voyage through the Straits of Malacca and Singapore. This waterway will likely challenge the present maritime business activities in ASEAN region. Therefore, the aim of this article is considering the pros and cons of the Kra Canal project to political, economic, sociological, legal, environmental, maritime security, and safety aspects by using the thematic analysis combined with PESETLM method. It is note that the new Canal will be beneficial for Vietnam in all aspects, especially maritime economy. Therefore, this article is pioneer research to a comprehensive analysis of the trend of the Vietnamese maritime industry awaiting to advantages of the Kra canal. Given the inherent strengths of the geographical features, the novel maritime business strategies are proposed to boost and reshape the Vietnam maritime economy, for instance the best policy to enhance co-operation and trade growth with other countries and regions; a variety of investigations of maritime business in strategy regions; enhancing Cai Mep - Thi Vai ports as hub port of Vietnam; the development of deep-water seaports and logistics services in Hon Khoai Island and long-term planning for main bunker compliance fuel supply or energy source for vessels; policies to enhance management and surveillance, and enforcement of the law, the innovation of administrative procedures in seaports, deep-water seaport electronic services, and electronic customs in the digital era.

This paper proposes a methodology for gantry route optimization in order to maximize the productivity of a odd-type surface mount device (SMD). A odd-type SMD is a machine that uses a gantry to mount electronic components on the placement point of a printed circuit board (PCB). The gantry needs a nozzle to move its electronic components. There is a suitability between the nozzle and the electronic component, and the mounting speed varies depending on the suitability. When it is difficult for the nozzle to adsorb electronic components, nozzle exchange is performed, and nozzle exchange takes a certain amount of time. The gantry route optimization problem is divided into the mounting order on PCB and the allocation of nozzles and electronic components to the gantry. Nozzle and electronic component allocation minimized the time incurred by nozzle exchange and nozzle-to-electronic component compatibility by using an mixed integer programming method. Sequence of mounting points on PCB minimizes travel time by using the branch-and-price method. Experimental data was made by randomly picking the location of the mounting point on a PCB of 800mm in width and 800mm in length. The number of mounting points is divided into 25, 50, 75, and 100, and experiments are conducted according to the number of types of electronic components, number of nozzle types, and suitability between nozzles and electronic components, respectively. Because the experimental data are random, the calculation time is not constant, but it is confirmed that the gantry route is found within a reasonable time.

우리나라에서는 일제강점기 때 일본수산시험장에서 1932년 동해 해양조사에 따른 해류도를 사용하였다. 80여년이 지난 오늘날에 지구 온난화로 동해의 해류도 바뀌었을 것으로 예상하였다. 이사부함대의 항로를 중심으로 동해의 해류를 알아보고자 직접 고안한 해류병에 이사부해류병이라 명명하고, 2014년부터 2020년까지 해류병 2,020개를 투하하여 57개를 회수하여 동해 해류의 흐름을 알아보았다. 이사부 장군이 505년 실직 군주로 부임하여 ‘왜 7년 동안이나 실직에 있었을까?’ 이사부 장군은 하슬라에 입성하려고 하였으나 고구려의 잔존 세력들이 남아있어 하슬라로 갈 수 없어 적의 후방을 급습하는 수륙양동작전을 계획하면서 전선을 만들었다. 이사부함대는 실직항에서 만들어져 강릉 안인으로 이동하여 상륙작전으로 고구려 군사를 물리치고 우산국 정벌 준비를 하였다. 이사부 장군은 목우사자의 계책으로 우산국을 정벌하고, 이사부함대는 우산국 복속으로 동해의 제해권을 확보하고 신라 수군 진영인 울산항으로 가서 왜구의 침입에 대비하였다. 본고에서 해류병 실험을 통하여 이사부항로에서 해류가 어떻게 이동하는지와 이사부가 수륙양동작전을 감행한 흔적들을 찾아보고, 이사부함대가 이동한 경로를 알아보고자 하였다. 그리고 대한민국 국토 균형 발전과 해양력 강화 차원에서 동해의 중심인 삼척에 국립해양문화재연구소 동해문화재과 신설과 동해해양유물전시관 건립을 추진해야 한다.

Facile process for the fabrication of multi-layer graphene thin film (MLGF) is reported here. Multi-layer graphene dispersion prepared by liquid-phase exfoliation of graphite was sprayed on a glass substrate by spray pyrolysis method. The structural, optical and electrical properties of the deposited MLGF are investigated. The sheets of graphene are deposited uniformly on the substrate and distribution of small graphene sheets with size of 300–500 nm can be observed in SEM image. AFM and micro-Raman results ensured that the spray-coated graphene thin film is composed of multi-layer graphene sheets. Spray coated graphene thin film showed significant optical transparency of 57% in the visible region (400–550 nm). MLGF possessed the electrical conductivity in the order of 744 S/m with surface resistivity of 3.54 k Ω/sq. The prepared liquid-phase exfoliated graphene thin film showed superior photoelectric response. The results of this study provided a framework for fabricating an optimized MLGF using a spray pyrolysis route for optoelectronics devices.

PURPOSES : The purpose of this study is to estimate the reduction in traffic noise in a double-layered specific porous pavement at roadsides based on variations in traffic volume and driving speed. METHODS : A statistical pass-by (SPB) method was employed in this study to measure noise. Variations in the following parameters were measured: running speed, heavy traffic percentage, and traffic volume. RESULTS : Quantitative analysis revealed that the double-layered porous pavement reduced noise levels by 9.16 dB(A) at a 95% confidence level at the sides of roads. CONCLUSIONS : As a countermeasure of traffic noise, porous pavement has been recommended. This research quantitatively proved that double-layered porous pavement can reduce traffic noise by more than 9.0 dB(A) at roadsides

The automotive industry has focused on the development of metallic materials with high specific strength, which can meet both fuel economy and safety goals. Here, a new class of ultrafine-grained high-Mn steels containing nano-scale oxides is developed using powder metallurgy. First, high-energy mechanical milling is performed to dissolve alloying elements in Fe and reduce the grain size to the nanometer regime. Second, the ball-milled powder is consolidated using spark plasma sintering. During spark plasma sintering, nanoscale manganese oxides are generated in Fe-15Mn steels, while other nanoscale oxides (e.g., aluminum, silicon, titanium) are produced in Fe-15Mn-3Al-3Si and Fe-15Mn-3Ti steels. Finally, the phases and resulting hardness of a variety of high-Mn steels are compared. As a result, the sintered pallets exhibit superior hardness when elements with higher oxygen affinity are added; these elements attract oxygen from Mn and form nanoscale oxides that can greatly improve the strength of high-Mn steels.