We propose a novel stripping solution containing acids (HCl and HNO3), an oxidant [(NH4)2S2O8], and complexing agents (NaCl and citric acid) to remove surface passivation layers from 14K gold alloys fabricated using an investment casting process. The optimized solution employing only HCl acid is determined by varying molar fractions of HCl and HNO3 on 14K yellow gold samples. Stripping properties are also identified for red and white gold alloy samples under the optimized stripping conditions. The removal of passivation layers, weight loss, and microstructure evolution are characterized using Raman spectroscopy, a precision scale, and optical microscopy. The proposed stripping solution effectively removes passivation layers more rapidly than conventional cyanide stripping. Weight loss increases linearly for up to 5 min for all 14K gold alloys. Red gold exhibits the greatest weight loss, followed by yellow gold and white gold. The results of microstructural analysis reveal that the conformal stripping occurs according to time. These results imply that the proposed oxidative chloride stripping might replace conventional cyanide stripping.

본 논문에서는 건물, 교량 및 해양구조물에 많이 적용되는 기본적인 형상인 벽면에 부착되어 있는 사각실린더 주변의 유동에 대해, 3개의 난류모델(v2-f 모델, k-ω 모델, k-ε 모델)을 적용하여 URANS 수치해석을 각각 수행하고, 그 결과를 비교하였다. 이 유동 은 물체의 모서리에서 발생하는 칼만와(karman vortex) 때문에 본질적으로 강한 비정상성을 가지고 있으며, 물체의 후류 영역에서도 매우 복잡한 유동구조를 가지고 있다고 알려져 있다. 3개의 난류모델이 적용된 수치해석으로부터 예측되는 평균 유동장과 지배적인 유동 의 주파수를 Wang et al.(2004; 2006)의 실험결과와 비교하였다. 비교 결과, v2-f 모델이 적용된 URANS 결과가 실험결과와 가장 유사한 결과를 보여주었고, k-ω 모델도 우수한 결과를 보인 반면, k-ε 모델은 본 대상 유동에 적용하기에 부족함을 확인하였다. 따라서 강한 박리가 존재하는 유동의 해석 시에는 v2-f 모델은 좋은 선택이다. 그리고 유동의 박리 제어를 위한 연구에 활용될 것으로 기대된다.

Heteroatoms in situ-doped hierarchical porous hollow-activated carbons (HPHACs) have been prepared innovatively by pyrolyzation of setaria viridis combined with alkaline activation for the first time. The micro-morphology, pore structure, chemical compositions, and electrochemical properties are researched in detail. The obtained HPHACs are served as outstanding electrode materials in electrochemical energy storage ascribe to the particular hierarchical porous and hollow structure, and the precursor setaria viridis is advantage of eco-friendly as well as cost-effective. Electrochemical measurement results of the HPHACs electrodes exhibit not only high specific capacitance of 350 F g−1 at 0.2 A g−1, and impressive surface specific capacitance (Cs) of 49.9 μF cm−2, but also substantial rate capability of 68% retention (238 F g−1 at 10 A g−1) and good cycle stability with 99% retention over 5000 cycles at 5 A g−1 in 6 M KOH. Besides, the symmetrical supercapacitor device based on the HPHACs electrodes exhibits excellent energy density of 49.5 Wh kg−1 at power density of 175 W kg−1, but still maintains favorable energy density of 32.0 Wh kg−1 at current density of 1 A g−1 in 1-ethy-3-methylimidazolium tetrafluoroborate ( EMIMBF4) ionic liquid electrolyte, and the excellent cycle stability behaviour shows the nearly 97% ratio capacitance retention of the initial capacitance after 10,000 cycles at current density of 2 A g−1. Overall, the results indicate that HPHACs derived from setaria viridis have appealing electrochemical performances thus are promising electrode materials for supercapacitor devices and large-scale applications.

After decades of vigorous development, data mining technology has achieved fruitful theoretical and application results. As a highly applicable subject, data mining technology has penetrated into various fields of the national economy, and has aroused great attention from academia and industry. A large amount of chart data is stored in the electronic chart database, and its application is very extensive, providing a valuable decision basis for managers in all walks of life. It is of great significance to establish a complete data management mechanism based on data mining technology. The traditional data analogy extraction technology, because of the data association index and the poor ability of data association, leads to the difference between the extraction data and the target data. Therefore, the application of data mining technology on electronic chart data management is studied. Data mining technology uses rough set to obtain the basic information of electronic chart data management according to similarity function, mining electronic chart data management association rules; through the comprehensive evaluanon data system of electronic chart data management, building rule base, setting up the evaluation index of electronic chart data management, achieving the similarity evaluation of the mining results. Experimental test results: compared with the traditional data analogy extraction technology, the results obtained by data mining technology have higher similarity with the target data and meet the requirements of electronic chart data management acquisition. It can be seen that this technology is more suitable for the application of electronic chart data management

The UNCLOS regulates complex balance of rights and duties among State parties. Its text was deliberately left vague as a result of compromise between the negotiating parties. To develop the legal norms, judges and arbitrators have referred to other rules of international law through systematic integration, rules of reference, and broad applicable law. However, judicial practice has expanded subject-matter jurisdiction beyond the UNCLOS, causing antinomy between Articles 288, on jurisdiction, and 293 of UNCLOS, on applicable law. Part XV of the UNCLOS has created an invisible community that would ideally lead the UNCLOS Tribunals to develop and follow a pragmatic approach as to the limits of their subject-matter jurisdiction in order to provide for judicial coherence. When interpreting the treaty, the establishment of genuine links between disputes and substantive rules under the UNCLOS is necessary, by which other rules of international law are firmly anchored to the interpreted texts under the UNCLOS.

The aim of this paper to provide grounds for Jeju 4.3 Human Rights educational activities to students. We have 2015 Revised Social Studies Curriculum Basic Direction - Goals and Contents of Korean History - Goals of Korean History (Revised July 27, 2018). It helps students to grasp the process of pre-modern Korean history, and use it as the basis for understanding self-identity and tradition comprehensively and systematically. Through the in-depth understanding of modern and contemporary history in Korea, students develop the ability to gain insight into the historical problems of modern Korean society. Through the process of exploring and interpreting various historical materials, students develop their ability to think critically with a critical mind and identify the historical roots of the problems faced by modern Korean society and their relevance to the world, and jointly seek ways to solve problems that can be realized at the learner level.

Chlorella gloriosa (Chlorellaceae, Trebouxiophyceae) was isolated from seawater off the coast of the Dokdo Islands in Korea. An axenic culture was established using the streak-plate method on f/2 agar media supplemented with antibiotics, allowing identification of the isolate by morphological, molecular, and physiological analyses. The morphological characteristics observed by light and electron microscopy revealed typical morphologies of C. gloriosa species. The molecular phylogenetic inference drawn from the small-subunit 18S rRNA sequence verified that the microalgal strain belongs to C. gloriosa. Additionally, gas chromatography-mass spectrometry analysis showed that the isolate was rich in nutritionally important omega-3 and -6 polyunsaturated fatty acids and high-performance liquid chromatography analysis revealed that the high-value antioxidants lutein and violaxanthin were biosynthesized as accessory pigments by this microalga, with arabinose, galactose, and glucose as the major monosaccharides. Therefore, in this study, a Korean marine C. gloriosa species was discovered, characterized, and described, and subsequently added to the national culture collection.

Spherical Li3V2(PO4)3 (LVP) and carbon-coated LVP with a monoclinic phase for the cathode materials are synthesized by a hydrothermal method using N2H4 as the reducing agent and saccharose as the carbon source. The results show that single phase monoclinic LVP without impurity phases such as LiV(P2O7), Li(VO)(PO4) and Li3(PO4) can be obtained after calcination at 800 oC for 4 h. SEM and TEM images show that the particle sizes are 0.5~2 μm and the thickness of the amorphous carbon layer is approximately 3~4 nm. CV curves for the test cell are recorded in the potential ranges of 3.0~4.3 V and 3.0~4.8 V at a scan rate of 0.01 mV s–1 and at room temperature. At potentials between 3.0 and 4.8 V, the third Li+ ions from the carbon-coated LVP can be completely extracted, at voltages close to 4.51 V. The carbon-coated LVP exhibits an initial specific discharge capacity of 118 mAh g–1 in the voltage region of 3.0 to 4.3 V at a current rate of 0.2 C. The results indicate that the reducing agent and carbon source can affect the crystal structure and electrochemical properties of the cathode materials.

우리나라 무궁화 품종 이름에 대한 자료를 찾아 정리하면서 수정하고 개선해야 할 사항을 발견하였으며 그 결과를 요약하면 다음과 같다. 첫 번째, 1979년대와 1980년대에 명명한 무궁화 품종 중 외국의 품종 이름을 우리말로 개명하여 부르는 것들은 원래 이름으로 바꾸어 주어야 할 것이다. 두 번째, 2000년 이후 공공기관 외 회사, 개인 등이 신품종 등록을 할 수 있게 됨에 따라 매우 많은 품종들이 등록되고 있는데 기존 품종들과의 구별이 쉽지 않은 문제를 야기하고 있다. 세 번째, 일본 품종의 경우 일본식 한자로 명명되어 있는데 도입 이후 품종명을 한국식 한자로 발음하고 명명, 명찰을 부착하여 한국품종으로 오해 할 수 있기 때문에 이를 개선하기 위해서는 한국식 한자가 아닌 원래 일본 품종명으로 적고, 일본식 이름으로 불러 주어야 할 것이다. 네 번째, 우리나라 무궁화는 학명으로 Hibiscus syriacus 인데, H. syriacus와는 이종인 H. sino-syriacus(대륜목근), H. paramutabilis(노산부용), H. mutabilis(부용) 등과 교배한 후대 들을 무궁화(H. syriacus)로 통합하여 부르고 있으나 이는 종간 잡종으로 구분, H. x hybrida로 구분해서 한다. 마지막으로, 1968년부터 외국에서 도입된 무궁화가 265품종에 달하는데 이 들 중 동일한 이름으로 중복 도입된 품종이 많아 적절한 명명 관리가 필요하다.

Recently, K-pop is leading the development of Korean pop culture. And it has established itself as a culture that is accepted and maintained voluntarily by the public worldwide. Cultural development in a region is important because it is a product of the social quality of society. With the debut of ‘Seo Taiji and Boys’ in 1992, the idol group music began in Korea. At present, BTS has formed a global fandom and has become one of the most successful cases among Hallyu content. Therefore, for the development of Korean pop music industry, this study analyzes in various ways what strategies of BTS have made them successful.

In order to investigate the applicability of ohmic heating in the blanching and heat sterilization process of vegetable foods, various electrical properties and heating characteristics were studied using intact potato. The electrical conductivity of potato with cell structure was 0.025 S/m, which was lower than that of starch and protein gel, and was increased linearly with increasing temperature. The temperature of ohmic heating was sharply increased from 8 min at 60 V, reaching 90°C after 10 min. The temperature rise was rapid at 60°C which was due to the increase of current flow by structural change related to the gelatinization of starch. The increase of temperature was faster when the frequency was increased, such as from 500 Hz to 1000 Hz. When potato was heated by ohmic heating at 60- 90 V and 40-120 Hz, rapid and uniform heat generation was possible. Thus, commercial utilization of ohmic heating can be applied for various types of vegetable foodstuff with ohmic heating was observed.

The photovoltaic properties of TiO2 used for the electron transport layer in perovskite solar cells(PSCs) are compared according to the particle size. The PSCs are fabricated and prepared by employing 20 nm and 30 nm TiO2 as well as a 1:1 mixture of these particles. To analyze the microstructure and pores of each TiO2 layer, a field emission scanning electron microscope and the Brunauer–Emmett–Teller(BET) method are used. The absorbance and photovoltaic characteristic of the PSC device are examined over time using ultraviolet-visible-near-infrared spectroscopy and a solar simulator. The microstructural analysis shows that the TiO2 shape and layer thicknesses are all similar, and the BET analysis results demonstrate that the size of TiO2 and in surface pore size is very small. The results of the photovoltaic characterization show that the mean absorbance is similar, in a range of about 400-800 nm. However, the device employing 30 nm TiO2 demonstrates the highest energy conversion efficiency(ECE) of 15.07 %. Furthermore, it is determined that all the ECEs decrease over time for the devices employing the respective types of TiO2. Such differences in ECE based on particle size are due to differences in fill factor, which changes because of changes in interfacial resistance during electron movement owing to differences in the TiO2 particle size, which is explained by a one-dimensional model of the electron path through various TiO2 particles.