Distance is a fundamental definition in fields such as geometry, mathematics, and physics. Because it is a very fundamental metric, it is not easy to create a new definition. In this study, we analyze existing distance definition and propose to generalize Euclidean distance and Manhattan distance, which are mainly used distance metric in existing distance definition. We analyze the definition of Minkowski distance, which is previously used as a concept of generalization along with Chebyshev distance, and the disadvantages of using this distance metric. By introducing a new perspective that interprets the existing Manhattan distance as a distance measured in four axes rather than simply adding the distances in each axis direction, this research introduces a new distance metric in two dimensions. This is a metric that generalizes the Euclidean distance and the Manhattan distance, and the proposed distance metric is derived from a geometrical aspect and an algorithm for calculating it is presented. We applied the existing distance definition and compared the differences through the results of generating a Voronoi area by the shortest distance from randomly distributed points in two dimensions. It is expected that the proposed method can be applied and expanded to the field of various graphics algorithms that use the distance metric.

Devices with negative differential transconductance (NDT) and negative differential resistance (NDR) have shown a strong potential for digital electronics with high information density due to their N-shaped current–voltage (I–V) characteristics leading to multiple threshold voltages ( Vths). The 2D materials, such as graphene, hBN, MoS2, WS2, etc., offer an attractive platform to achieve NDT and NDR because of the absence of dangling bonds on the surface, leading to a high-quality interface between the layers. The 2D materials' unique property of the weak van der Waals (vdW) interactions without dangling bonds on the heterostructure devices shows the way for the applications more than-Moore devices. This review holds a well-timed overview of 2D materials-based devices to develop future multi-valued logic (MVL) circuits exhibiting high information density. Notably, the recent advances in emerging 2D materials are reviewed to support the directions for future research on MVL applications.

Molybdenum disulfide ( MoS2) has been one of the most promising members of transition-metal dichalcogenides materials. Attributed to the excellent electrical performance and special physical properties, MoS2 has been broadly applied in semiconductor devices, such as field effect transistors (FETs). At present, the exploration of further improving the performance of MoS2- based FETs (such as increasing the carrier mobility and scaling) has encountered a bottleneck, and the application of high-κ gate dielectrics has become an effective approach to change this situation. Atomic layer deposition (ALD) enables high-quality integration of MoS2 and high-κ gate dielectrics at the atomic level. In this review, we summarize recent advances in the fabrication of two-dimensional MoS2 FETs using ALD high-κ materials as gate dielectrics. We first briefly discuss the research background of MoS2 FETs. Second, we expound the electrical and other essential properties of high-κ gate dielectrics, which are essential to the performance of MoS2 FETs. Finally, we focus on the advances in fabricating MoS2 FETs with ALD high-κ gate dielectrics on MoS2, as well as the optimized ALD processes. In addition, we also look forward to the development prospect of this field.

Background: Considering the kinetic chain of the lower extremity, a pronated foot position (PFP) can affect malalignment of the lower extremity, such as a dynamic knee valgus (DKV). Although the DKV during several single-leg movement tests has been investigated, no studies have compared the differences in DKV during a single-leg step down (SLSD) between subjects with and without PFP. Objects: The purpose of this study was to compare the DKV during SLSD between subjects with and without PFP. Methods: Twelve subjects with PFP (9 men, 3 women) and 15 subjects without PFP (12 men, 3 women) participated in this study. To calculate the DKV, frontal plane projection angle (FPPA), knee-in distance (KID), and hip-out distance (HOD) during SLSD were analyzed by twodimensional video analysis software (Kinovea). Results: The FPPA was significantly lower in PFP group, compared with control group (166.4° ± 7.5° and 174.5° ± 5.5°, p < 0.05). Also, the KID was significantly greater in PFP group, compared with control group (12.7 ± 3.9 cm and 7.3 ± 2.4 cm, p < 0.05). However, the HOD not significantly differed between two groups (12.7 ± 1.7 cm and 11.4 ± 2.5 cm, p > 0.05). Conclusion: The PFP is associated with lower FPPA and greater KID. When assess the DKV during SLSD, the PFP should be considered as a crucial factor for occurrence of DKV.

본 논문에서는 정전기 흡착패드를 구성하는 곡면형 전극의 기하학적 엄밀성을 고려하기 위해 정전기 문제에 대하여 CAD에서 사 용하는 NURBS 기저함수를 직접 사용하는 아이소-지오메트릭 해석 기법을 도입하였다. 정전기 흡착력을 곡선 접촉면에서 구하는데 법선 벡터의 영향이 크므로 엄밀한 기하형상을 고려하는 아이소-지오메트릭 해석이 강점을 갖는다. 수치 예제를 통해 곡면과 평면에서 반복 구조의 유무에 따른 파라메터 연구를 수행하여 곡면형 전극의 흡착력이 좋은 성능을 가짐을 보였다. 정전기 흡착력의 성분을 분석하였을 때 정전기 흡착력의 차이는 법선 성분 전기장의 증가로 인한 것으로 파악되었다. 결론적으로 곡면형 전극에서도 전극 사이 거리가 가까워지는 아래로 볼록인 경우가 가장 성능이 좋고, 위로 볼록인 경우에는 성능이 가장 낮음을 보였다.

In this study, photocatalytic degradation of ammonia in petrochemical wastewater is investigated by solar light photocatalysis. Two-dimensional ultra-thin atomic layer structured MoS2 are synthesized via a simple hydrothermal method. We examine all prepared samples by means of physical techniques, such as SEM-EDX, HRTEM, FT-IR, BET, XRD, XPS, DRS and PL. And, we use fullerene modified MoS2 nanosheets to enhance the activity of photochemically generated oxygen (PGO) species. Surface area and pore volumes of the MoS2-fullerene samples significantly increase due to the existence of MoS2. And, PGO oxidation of MB, TBA and TMST, causing its concentration in aqueous solution to decrease, is confirmed by the results of PL. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the PGO effect increase in the case with modified fullerene. The experimental results show that this heterogeneous catalyst has a degradation of 88.43% achieved through visible light irradiation. The product for the degradation of NH3 is identified as N2, but not NO2−or NO3−.

Interest in eco-friendly materials with high efficiencies is increasing significantly as science and technology undergo a paradigm shift toward environment-friendly and sustainable development. MXenes, a class of two-dimensional inorganic compounds, are generally defined as transition metal carbides or nitrides composed of few-atoms-thick layers with functional groups. Recently MXenes, because of their desirable electrical, thermal, and mechanical properties that emerge from conductive layered structures with tunable surface terminations, have garnered significant attention as promising candidates for energy storage applications (e.g., supercapacitors and electrode materials for Li-ion batteries), water purification, and gas sensors. In this review, we introduce MXenes and describe their properties and research trends by classifying them into two main categories: transition metal carbides and nitrides, including Ti-based MXenes, Mo-based MXenes, and Nb-based MXenes.

사람들에게 가장 일상적인 시각 대상이었던 대지와 하늘, 바닷가와 강가의 산과 모래밭, 그리고 숲속의 오솔길, 그 길가에 여기저기 서 있는 크고 작은 나무들, 개울에 흐르는 잔잔한 물소리, 가끔은 크고 작은 자갈에 부딪히는 소리들은 우리에게 맑은 숨을 쉬게 하고 작은 힘을 솟게 해주었다. 겨울 산과 여름 산의 정서가 다름은 우리가 자주 느끼는 일이다. 바다에 있는 산은 작게 보이고 강가에 있는 산은 크게 보인다. 사람이 서서 볼 수 있는 거리 때문이겠지만 우리에게 주는 정서 역시 제각기 다르 다. 특히 여름철 해질 무렵 연한 보랏빛 석양에서부터 검 짙은 갈색으로 변할 때까지 지켜본다는 것도 자연의 일부분을 충분히 경험하는 방법이라고 생각했다. 그러나 지금은 아파트로 둘러 싸여 있어 그런 기억들이 2차원의 공간에서만 볼 수 있는 먼 추억이 되어버렸다. 2차원 공간? 우리는 3차원에서 생활하고 있기 때문에 2차원 공간이 생소하다. 그러나 실제로 우리는 생활 속에서 2차원 공간을 많이 사용하고 있다. 책, 사진, 문서, 벽면 등등. 그러나 지금 내가 하고 싶은 말은 그런 것도 중요하지만 3차원의 세계에서 살고 있는 우리가 생홣 밖의 일도 저지를 수 있다는 것이다. 상상, 공상, 환상, 망상, 그리고 창의적 발상의 요람이 될 수 있다는 것이다. 그것을 표현하는 방법은 각자 다를 수 있다. 이를테면 글자로 쓰는 것, 선으로 그리는 것, 색으로 칠하는 것 등등. 최초의 원시인도 기계문명시대에 사는 현대인도 하기 힘든, ‘인류의 유산’으로 남겨놓은 것들을 우리는 알고 있고 볼 수도 있다. 암각화, 벽화, 골각화 등등. 캄캄한 동굴 안에, 거대한 암석에 그러한 그림들을 그린 이유가 무엇이었을까, 무슨 도구를 사용했으며 누구를 향한 절규였을까. 필경 목숨을 걸고 그런 일을 했다면, 생각할수록 더 궁금해지지 않을 수 없다. 그런데 필자가 이런 이야기를 하는 것을 나이가 많아서 할 일이 없기 때문이라고 생각해도 괜찮다. 왜냐 하면 우리나라 사람 대부분은 이러한 역사적이거나 철학적인 얘기를 꺼내면 밥 맛 없는 소리 한다고 치부 하는 경우가 많기 때문이다. 자기 자신을 잘 모르고, 우리 역사를 잘 모르고, 인류의 역사를 잘 몰라도 우리는 잘 먹고 잘 살고 있기 때문인 것 같다. 철학에 물리적 실체가 있다면 아마 예술이라는 걸로 표현될 것이다. 어떤 모습, 무슨 색깔, 무슨 구상이 든 그것을 표현하는 것은 오롯이 작가 자신일 것이다. 관람객이 작품을 그저 쓱 쳐다본다면 그 작품은 같은 위치와 같은 장면만 보여준다. 관람객의 사회적 위치나 시선과는 상관없이 민 낮의 정서로 그 사람 과 마주친다. 그러면 관람객은 그림 속의 사심을 자기의 마음으로 하나씩 벗겨낸 다음 맨 마지막으로 보 통 이렇게 이야기 한다. “이게 뭐야? 나도 할 수 있겠다!” 그러고는 종종걸음으로 작품 앞을 떠난다. 동일한 시간에 올실 안의 풍경과 문 밖 강가의 풍경이 다를지라도 생명의 리듬은 같다는 것을 우리는 알고 있다. 물풀에 잠시 앉아 있는 까만 잠자리나 빨간 고추잠자리가 하는 일은 같을지도 모른다. 그래서 지구상에 모든 생명은 ‘질서’라는 카테고리 안에서 잘 살고 있는지도 모른다.

산업화와 기후 변화는 깨끗한 식수에 대한 수요 증가를 초래하였다. 막분리공정을 이용한 해수담수화는 물의 수요에 대한 요구를 채울 수 있는 경제적으로 실현 가능한 대안 중 하나이다. 막분리공정에서 2차원 재료들은 기존 역삼투분리막 (reverse osmosis membrane) 기반의 폴리아마이드 박막복합막(TFC-PA)과 비교하였을 때 막의 강도를 높여주고 투수성을 용이하게 하며 높은 염제거율 및 높은 선속률과 선택성을 보여준다. 이 리뷰 논문에서는 재료, 합성, 특징, 해수담수화 과정을 기반으로 다양한 2차원 재료로 구성된 복합막들을 소개하고 있다.

The flow analysis of two dimensional transient flow over the obstacles with rectangular cross sections was performed. And 190 velocity distributions for each aspect ratio were imaged to provide input data for convolutional neural network learning. The classification and regression methods were used in estimating the aspect ratio from given velocity distributions. As a result the classification method was more exact than the regression method. But both the classification and regression methods gave relatively accurate prediction of the defined aspect ratio judging from the imaged velocity distributions. This confirms that the deep learning technique is applicable to the flow analysis.

One- and two-dimensional carbon nanomaterials were tested as adsorbents for the elimination of two anionic dyes, reactive red 2 and methyl orange, and the cationic dye methylene blue from aqueous solutions under the same conditions. Carbon nanomaterials performed well in the removal of dyes. Surface oxygenated groups in the nanomaterials improved the cationic dyes’ adsorption, but not the adsorption of the anionic dye. The interactions between nanomaterials and dyes were verified by infrared and Raman spectroscopy. The pseudo-second order kinetic model was better fitted to the kinetic experimental data than the Elovich and pseudo-first order models. The equilibrium adsorption data were best fitted by the Langmuir model. The dimensions and morphology of the carbon nanomaterials play an important role in the adsorption of the three dyes. The main mechanism of adsorption of anionic dyes is by the interactions of the aromatic rings of the dye structures and π delocalized electrons on carbon nanostructures; the adsorption of cationic dye is mainly due to electrostatic interactions.

Effect of the nonuniform grid on the two-dimensional transport equation was investigated in terms of theoretical analysis and finite difference method (FDM). The nonuniform grid having a typical structure of the numerical weather forecast model was incorporated in the vertical direction, while the uniform grid was used in the zonal direction. The staggered and non-staggered grid were placed in the vertical and zonal direction, respectively. Time stepping was performed with the third-order Runge Kutta scheme. An error analysis of the spatial discretization on the nonuniform grid was carried out, which indicated that the combined effect of the nonuniform grid and advection velocity produced either numerical diffusion or numerical adverse-diffusion. An analytic function is used for the quantitative evaluation of the errors associated with the discretized transport equation. Numerical experiments with the non-uniformity of vertical grid were found to support the analysis.

범용유한요소프로그램인 Abaqus의 확장유한요소법(XFEM)의 사용성 검증을 위하여 2차원 모델에 적용하여 수치해석을 수행하였다. 기존의 연구에 많이 사용되었던 응집요소(cohesive element) 모델은 균열 경로를 예측하고 요소를 삽입하여야 하는 단점 때문에 실제 균열을 모사하는데 한계가 있다. 이러한 이유로 응력의 방향성 및 특이성을 바탕으로 균열의 경로를 예측하는 확장유한요소법(XFEM)이 균열 해석에 있어서 더 발전된 방법으로 이용되어 왔다. 이번 연구에서는 균열의 경로가 자명한 2차원 모델에 사용하여 응집요소해석과 XFEM에 응집요소의 물성을 적용한 해석을 비교하고 XFEM 적용의 타당성을 확인하였다. 수치해석으로 균열 발생 직전의 응력분포 및 응력 특이성을 확인하고 실제 균열 발생경로와의 비교를 한다. 본 연구를 바탕으로 몇 가지의 한계를 극복하면 실제 복잡한 모델의 실제 균열진전해석을 수행하여 균열을 모사할 수 있을 것으로 기대된다.

For several decades, attribute classification methods using the asymmetrical relationship between an attribute performance and the satisfaction of that attribute have been explored by numerous researchers. In particular, the Kano model, which classifies quality attributes into 5 elements using simple questionnaire and two-dimensional evaluation table, has gained popularity: Attractive, One-dimensional, Must-be, Indifferent, and Reverse quality. As Kano's model is well accepted, many literatures have introduced categorization methods using the Kano's evaluation table at attribute level. However, they applied different terminologies and classification criteria and this causes confusion and misunderstanding. Therefore, a criterion for quality classification at attribute level is necessary. This study is aimed to suggest a new attribute classification method that sub-categorizes quality attributes using 5-point ordinal point and Kano's two-dimensional evaluation table through an extensive literature review. For this, the current study examines the intrinsic and extrinsic problems of the well-recognized Kano model that have been used for measuring customer satisfaction of products and services. For empirical study, the author conducted a comparative study between the results of Kano's model and the proposed method for an e-learning case (33 attributes). Results show that the proposed method is better in terms of ease of use and understanding of kano's results and this result will contribute to the further development of the attractive quality theory that enables to understand both the customers explicit and implicit needs.