• Journal of Electrochemical Science and Technology
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• 제11권3호
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• pp.220-237
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• 2020

Modern electrochemical energy devices involve generation and reduction of fuel gases through electrochemical reactions of water splitting, alcohol oxidation, oxygen reduction, etc. Initially, these processes were executed in the presence of noble metal-based catalyst that showed low overpotential and high current density. However, its high cost, unavailability, corrosion and related toxicity limited its application. The search for alternative with high stability, durability, and efficiency led scientists towards carbon nanoparticles supported catalysts which has high surface area, good electrical conductivity, tunable morphology, low cost, ease of synthesis and stability. Carbon nanoparticles are classified into two groups based on morphology, one and zero dimensional particles. Carbon nanoparticles at zero dimension, denoted as carbon dots, are less used carbon support compared to other forms. However, recently carbon dots with improved electronic properties have become popular as catalyst as well as catalyst support. This review focused on the recent advances in electrocatalytic activities of carbon dots. The mechanisms of common electrocatalytic reactions and the role of the catalysts are also discussed. The review also proposed future developments and other research directions to overcome current limitations.

• Archives of Metallurgy and Materials
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• 제65권4호
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• pp.1323-1327
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• 2020

In this paper, we have studied the evolution of morphology and brazing behavior of Ag-28Cu alloy filler processed by high energy ball milling. The milling of the powder mixture was carried out for 40 h. The structural and morphological analyses were performed by the X-ray diffraction and scanning electron microscopy. The melting temperature of the braze filler was determined by differential thermal analysis. The filler wetting properties were assessed from the spread area ratio measurements on various Ti substrates. The results indicate that the ball milling can effectively depress the filler melting point and enhance the brazeability. The milled powder mixture showed Ag(Cu) solid solution with a crystallite size of 174-68 nm after 40 h. It was shown that the high energy ball milling can be a potential method to develop low temperature brazing fillers for advanced microjoining applications.

• Animal Systematics, Evolution and Diversity
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• 제39권4호
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• pp.264-271
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• 2023

The edible jellyfish Rhopilema esculentum occurs in waters throughout northeastern Asia, including in Korea, China, and Japan. In Korean waters, R. esculentum has appeared in two regions (Gangwha and Muan). Based on the appearance of young medusae and coastal distribution records, these two regions may be key R. esculentum breeding sites. In the present study, we investigate and compare the genetic structure of R. esculentum in the two regions using mitochondrial sequences (16S ribosomal RNA and cytochrome c oxidase subunit I). The genetic diversity of the R. esculentum population at Ganghwa exceeded that of the population at Muan. Despite considerable geographic separation (400 km) between the two regions(Gangwha and Muan), our haplotype network suggests that the Gangwha and Muan populations of R. esculentum are related. The simple and monotonous genetic structure of the Muan population shows that R. esculentum emergence is relatively recent. In contrast, the Gangwha population shows evolution. Moreover, jellyfish of the Gangwha population are genetically diverse and remain constant despite environmental fluctuations in the Han River. The Gangwha area is considered to be the old origin of R. esculentum in Korea.

• 농촌지도와개발
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• 제5권1호
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• pp.45-59
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• 1998

Regional agricultural research has been activated since the mid of 1980s by the government`s integrated rural development policy based on regional unit(kun). It is called upon to meet the challenges which the agriculture confronts in the general evolution of the society. However, regretfully it seems this new approach has not succeeded in developing its own theoretical tools for the diagnostic analysis of regional agriculture. So, this study would introduce the french agrarian system theory which has been developed by the interdisciplinary research groups of the France`s National Agricultural Research Institute, which is now filtering outside the country to various parts of the world. It attempts also to apply the above theory to analyse one of agricultural regions located in the province Cheollabukdo, so as to see its theoretical pertinency and efficiency in the regional agricultural development planning which constitute the main part of the regional planning.

• Animal Systematics, Evolution and Diversity
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• 제30권2호
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• pp.59-64
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• 2014

Three species of the genus Sciota Hulst, 1888 are recognized from Northeast China: Sciota cynicella (Christoph, 1881), Sciota fumella (Eversmann, 1844), and Sciota adelphella (Fischer von R$\ddot{o} $slerstamm, 1836), of which Sciota cynicella (Christoph, 1881) is reported for the first time from China. This species can be distinguished from congeners by the gray color of basal area, the straight antemedial line and the distinct postmedial line on the forewing; by the stout aedeagus in male genitalia. In this study, a key to Northeastern Chinese species of genus Sciota is presented, and the illustrations of adults and genitalia are also provided.

• International Journal of Computer Science & Network Security
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• 제23권11호
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• pp.169-177
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• 2023

Network security is now more crucial than ever for consumers, companies, and military clients. Security has elevated to the top of the priority list since the Internet's creation. The evolution of security technology is now better understood. The area of community protection as a whole is broad and dynamic. News from the days before the internet and more recent advancements in community protection are both included in the topic of observation. Recognize current research techniques, previous Defence strategies that were significant, and network attack techniques that have been used before. The security of various domain names is the subject of this article's description of bibliographic research.

• 한국주거학회논문집
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• 제11권1호
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• pp.37-44
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• 2000

The purpose of this research is to examine the evolution of low-cost sales housing and give suggestions for the future housing for the 21st century. This paper investigates the trends of low-cost suburban housing since world War II, as examplified by the Levitt housing in the Northeastern regions of the States. This research analyzes the trends of 14 variables including total floor area. lot size, living room size, kitchen size, mean bedroom size, master bedroom size, number of bedrooms, number of bathrooms, family room, garage, number of story, appliances and features, values, and values per sq ft. Nine entry-level houses were chosen as cases for comparative purpose at different points in time from 1940's to 1990's. This research finds that house sizes have been grown until 1960s, but this trend has reversed with shrinking economy and changing family lifestyles. The trend for smaller housing equipped with several features and convenient equipments will be continued for the next decades to come.

• 인터넷정보학회논문지
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• 제13권4호
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• pp.53-62
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• 2012

객체분할은 영상처리와 컴퓨터비전분야의 상당히 어려운 연구대상이다. 그레이스케일 영상에 대한 영상분할은 매우 많은 방법이 발표되었으며 다양한 영상특징과 처리방법이 제시되었다. 이러한 방법들은 대개 자연상태의 칼라 영상에 적용되기 어렵다. 본 논문에서는 기하학적인 Active Contour 모델의 수정된 형태, 즉 거리정규화레벨셋(distance regularized level set evolution: DRLSE)을 이용한 방법을 제시하여 스피드 함수가 이러한 칼라요소를 반영하도록 하였으며 실험결과 정확성과 시간효율성에 있어서 우수한 결과를 보여주었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.285-285
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• 2016

Resistive random access memory devices have been widely studied due to their high performance characteristics, such as high scalability, fast switching, and low power consumption. However, fluctuation in operational parameters remains a critical weakness that leads to device failures. Although the random formation and rupture of conducting filaments (CFs) in an oxide matrix during resistive switching processes have been proposed as the origin of such fluctuations, direct observations of the formation and rupture of CFs at the device scale during resistive switching processes have been limited by the lack of real-time large-area imaging methods. Here, a novel imaging method is proposed for monitoring CF formation and rupture across the whole area of a memory cell during resistive switching. A hybrid structure consisting of a resistive random access memory and a light-emitting diode enables real-time monitoring of CF configuration during various resistive switching processes including forming, semi-forming, stable/unstable set/reset switching, and repetitive set switching over 50 cycles.

• 한국세라믹학회지
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• 제37권5호
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• pp.479-490
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• 2000

The microstructure of Ni-YSZ composite as an anode of SOFC was investigated as a function of Ni content(10-70 vol%) in order to examine the correlation between microstructural-and electrical property. Image analysis based on quantitative microscopy theory was performed to quantify the microstructural property. We could get the informations about the size and distribution, contiguity and interfacial area of each phase or between the phases from the image analysis. According to the image analysis, contiguity between the same phae was mainly dependent on the amount of the phase while the contiguity between different phases was additionally influenced by the microstructural changes, especailly by the coarsening of the Ni phase. The whole length of pores perimeter was increased as Ni content increased, which indicated the overall microstructural evolution was mostly related with the coarsening of Ni phase. Ni-Ni interfacial area was also gradually increased as Ni content increased but controlled by pore phase at low Ni content region and by YSZ phase at intermediate Ni content region. These quantified microstructural properties were used to characterize the electrical properties of Ni-YSZ composite.