• Journal of Astronomy and Space Sciences
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• 제38권1호
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• pp.55-63
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• 2021

The universe is well known to be consists of dark energy, dark matter and the standard model (SM) particles. The dark matter dominates the density of matter in the universe. The dark matter is thought to be linked with dark photon which are hypothetical hidden sector particles similar to photons in electromagnetism but potentially proposed as force carriers. Due to the extremely small cross-section of dark matter, a large amount of data is needed to be processed. Therefore, we need to optimize the central processing unit (CPU) time. In this work, using MadGraph5 as a simulation tool kit, we examined the CPU time, and cross-section of dark matter at the electron-positron collider considering three parameters including the center of mass energy, dark photon mass, and coupling constant. The signal process pertained to a dark photon, which couples only to heavy leptons. We only dealt with the case of dark photon decaying into two muons. We used the simplified model which covers dark matter particles and dark photon particles as well as the SM particles. To compare the CPU time of simulation, one or more cores of the KISTI-5 supercomputer of Nurion Knights Landing and Skylake and a local Linux machine were used. Our results can help optimize high-energy physics software through high-performance computing and enable the users to incorporate parallel processing.

• Membrane and Water Treatment
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• 제7권4호
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• pp.341-353
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• 2016

Papermaking reconstituted tobacco is an important strategy for recycling the waste tobacco residues. To indentify the influences of the inorganic components on harmful components delivery in cigarette smoke, a self-made electrodialysis stack was assembled to desalt the tobacco extract. The influences of the applied current and extract content on the removal rate of the inorganic ions were investigated. Results indicated that the applied current was a dominant impact on the desalination performance. High currents lower than the limiting current density could accelerate the desalting efficiency but cause higher energy consumption. A current of 2 A, or current density of ${\sim}11mA{\cdot}cm^{-2}$, was an optimal choice by considering both the energy consumption and desalting efficiency. A 20% tobacco extract was an appropriate content for the electrodialysis process. More than 90% of inorganic ions could be removed under the optimum condition. The preliminary result indicated that removal of inorganic components was beneficial to decrease the harmful component delivery in cigarette smoke. Naturally, ED is an environmentally friendly and high-effective technology for desalting the tobacco extract.

• 한국표면공학회지
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• 제56권6호
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• pp.412-419
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• 2023

Anion exchange membrane electrolysis is considered a promising next-generation hydrogen production technology that can produce low-cost, clean hydrogen. However, anion exchange membrane electrolysis technology is in its early stages of development and requires intensive research on electrodes, which are a key component of the catalyst-system interface. In this study, we optimized the pressure conditions of the hot-pressing process to manufacture cobalt oxide electrodes for the development of a high uniformity and high adhesion electrode production process for the oxygen evolution reaction. As the pressure increased, the reduction of pores within the electrode and increased densification of catalytic particles led to the formation of a uniform electrode surface. The cobalt oxide electrode optimized for pressure conditions exhibited improved catalytic activity and durability. The optimized electrode was used as the anode in an AEMWE single cell, exhibiting a current density of 1.53 A cm^-2 at a cell voltage of 1.85 V. In a durability test conducted for 100 h at a constant current density of 500 mA cm^-2, it demonstrated excellent durability with a low degradation rate of 15.9 mV kh^-1, maintaining 99% of its initial performance.

• 대한영양사협회학술지
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• 제12권1호
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• pp.10-17
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• 2006

The purpose of this study was to examine the correlation between nutrient intakes and bone mineral density in female university students. A total 27 female university students were measured the anthropometric characteristics, dietary intake and the bone mineral density of carpus using DEXA. The average age, height, weight, % body fat, WHR, and BMI of the subjects were 22.7 years, 161.5 cm, 57.0 kg, 29.9%, 0.8, 21.8 kg/$m^2$, respectively. Bone mineral density of ultradis and distal carpus as T-value were -1.5 and -0.4, respectively. The daily energy intake of the subjects was 1589.0kcal. And the intakes of energy, calcium, iron, zinc, vitamin $B_2$, and folic acid did not meet the Korean RDAs. The daily total food intake of the subjects was 1011.0g and food intake from cereals and vegetables was high. The major food groups of mineral intake were vegetables/cereals/milks/fishes for calcium, cereals/meat/vegetables/fishes for phosphorus, cereals/vegetables/meats for iron, seasonings/vegetables/cereals for sodium, vegetables/cereals/seasonings for potassium, and cereals/meats for zinc. The body weight and body mass index were significantly positive correlated to the bone mineral density of average carpus, respectively. The intakes of animal calcium and vitamin $B_2$ were significantly negative correlated to the bone mineral density of average carpus, respectively. In conclusion, bone mineral density in carpus and nutrient intakes of some female university students were low. Therefore, health management and the study on relation between bone mineral density in various site and long-term intakes of nutrients in many subjects are required.

• 공업화학
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• 제23권3호
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• pp.247-252
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• 2012

전기자동차, 하이브리드 자동차의 필요성과 스마트 IT 기기의 급속한 발전으로 인한 고용량 고출력 전지의 수요가 급증하고 있다. 현재 상용화 된 리튬이온전지는 기술적 문제에 의해 제한된 에너지 밀도만이 이용되고 있어서 보다 높은 에너지 밀도를 갖는 리튬-황 및 리튬-공기전지 개발이 주목 받고 있다. 새로운 Li 배터리 시스템의 양극물질인 황과 산소는 유사한 물리화학적 특성을 갖고 풍부한 자원 매장량으로 상용화가 어렵지 않을 것으로 전망한다. 따라서 본 총설에서는 리튬-황 및 리튬-공기 전지 시스템의 다공성 구조 양극개발, 양극과 전해질의 계면반응 최적화 및 높은 내구성이 있는 리튬음극 개발과 같은 공통 이슈를 해결하고자 하는 비전을 제시하고자 한다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(3)
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• pp.213-218
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• 1996

Characteristics of high density U-Mo alloy powder prepared by centrifugal atomization have been examined. The results indicate that the majority of the atomized U-Mo alloy particles has a smooth surface and frequently near-perfect spheroidal shape with few satellites attached. The size distribution of atomized U-Mo alloy powder shows the mono-modal size distribution seen in ligament disintegration mechanism. All phases of atomized alloy powder below 150$\mu\textrm{m}$ irrespectively to particle size are found to be ${\gamma}$-U (cubic structure) phases with isotropic structure and not to be U$_2$Mo phase at all. The microstructure of atomized U-Mo alloy particulates has micro-crystalline structure with non-dendritic gram supersaturated with Mo element. Also the grain size of ${\gamma}$ -U tends to decrease with the decrease of the powder diameter.

• 한국군사과학기술학회지
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• 제6권3호
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• pp.86-102
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• 2003

Polynitrogen molecules are of great interest as potential high energy-density materials, and hence such structures of various isomers of nitrogen clusters have been calculated using molecular modeling techniques by the researchers from various sectors of scientific institutions. In this article, the predicted meta-stable structures of these hypothetical molecules have been thoroughly reviewed.

• 한국분말재료학회지
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• 제30권6호
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• pp.509-515
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• 2023

Lead-free perovskite ceramics, which have excellent energy storage capabilities, are attracting attention owing to their high power density and rapid charge-discharge speed. Given that the energy-storage properties of perovskite ceramic capacitors are significantly improved by doping with various elements, modifying their chemical compositions is a fundamental strategy. This study investigated the effect of Zn doping on the microstructure and energy storage performance of potassium sodium niobate (KNN)-based ceramics. Two types of powders and their corresponding ceramics with compositions of (1-x)(K,Na)NbO₃-xBi(Ni_2/3Ta_1/3)O₃ (KNN-BNT) and (1-x)(K,Na)NbO₃-xBi(Ni_1/3Zn_1/3Ta_1/3)O₃ (KNN-BNZT) were prepared via solid-state reactions. The results indicate that Zn doping retards grain growth, resulting in smaller grain sizes in Zn-doped KNN-BNZT than in KNN-BNT ceramics. Moreover, the Zn-doped KNN-BNZT ceramics exhibited superior energy storage density and efficiency across all x values. Notably, 0.9KNN-0.1BNZT ceramics demonstrate an energy storage density and efficiency of 0.24 J/cm³ and 96%, respectively. These ceramics also exhibited excellent temperature and frequency stability. This study provides valuable insights into the design of KNN-based ceramic capacitors with enhanced energy storage capabilities through doping strategies.

• 대한영양사협회학술지
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• 제8권3호
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• pp.240-249
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• 2002

The purpose of this study was to investigate the effects of alcohol intake on nutritional intake status among the college students. The subjects were divided three groups; no-alcohol group(n=78), alcohol group(n=113), and high-alcohol group(n=82) according to intake and frequency of alcohol. And they were observed characteristics of alcohol drinking, dietary behavior and attitude, and nutrient intakes using questionnaires. The frequency of skipping meals in breakfast in high-alcohol group were higher than in other two groups(p<0.01). There were no significant differences in frequency of skipping meals of lunch and supper, reason why skipped meals, and total score of dietary attitude among three groups. However, the score of dietary attitude about no heavy drinking and smoking in high-alcohol group was higher than in other two groups(p<0.01). There were significant difference in vitamin B2 intake, alcohol intake, and energy intakes from carbohydrate, lipid, and alcohol among three groups(p<0.05, p<0.05, p<0.01, p<0.05, p<0.05). Compared energy intake of high-alcohol group with other two groups, intake from carbohydrate was low and intakes from lipid and alcohol were high. In the nutrient density, plant protein and carbohydrate in no-alcohol group, lipid and vitamin B2 in alcohol group, and animal lipid in high-alcohol group were highest among three groups. NAR and MAR were not significant difference among three groups except that NAR of P in alcohol group is highest among three groups(p<0.05). In conclusion, students high consuming alcohol have unhealty dietary behaviors in the light of high frequency of skipping breakfast, undesirable dietary attitude of alcohol drinking and smoking, and low energy inake from diet. Therefore, this results should be considered in meal management and nutritional education for student of high alcohol consumption.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권3호
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• pp.356-363
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• 2014

In this paper, we propose a new memristor-based crossbar array architecture, where a single memristor array and constant-term circuit are used to represent both plus-polarity and minus-polarity matrices. This is different from the previous crossbar array architecture which has two memristor arrays to represent plus-polarity and minus-polarity connection matrices, respectively. The proposed crossbar architecture is tested and verified to have the same performance with the previous crossbar architecture for applications of character recognition. For areal density, however, the proposed crossbar architecture is twice better than the previous architecture, because only single memristor array is used instead of two crossbar arrays. Moreover, the power consumption of the proposed architecture can be smaller by 48% than the previous one because the number of memristors in the proposed crossbar architecture is reduced to half compared to the previous crossbar architecture. From the high areal density and high energy efficiency, we can know that this newly proposed crossbar array architecture is very suitable to various applications of analog neuromorphic computing that demand high areal density and low energy consumption.