관광자의 수단선택 행위에 관한 연구

Rizwan,윤재웅,박웅진 대한교통학회 2019 대한교통학회 학술대회지 Vol.80 No.-

하늘공원, 태종대 등 산책하기 좋은 환경을 조성하여 도보 그 자체에 목적을 두게 하는 관광지들이 많이 생겨나고 있다. 이러한 관광지들은 교통약자들이 전체 코스를 도보로 완주하기엔 다소 어려움이 발생할 수 있어, 일정 구간 혹은 전체 구간에 대해 교통수단을 제공하고 있다. 본 연구에서는 관광지의 교통수단 선택행위가 통행시간 및 요금수준에 의해 얼마나 크게 좌우되는 지 알아보고자 한다. 분석은 다항로짓모형을 통해 진행하며, 최종적으로 도출된 관광지에서의 시간가치가 일반적인 상황에서의 시간가치와 얼마나 차이를 나타내는 지 알아본다. 최종적으로 관광단지 교통수단의 적정요금수준을 판단할 수 있는 근거 제시가 주요 목적이다.

Computer based estimation of backbone curves for hysteretic Response of reinforced concrete columns under static cyclic lateral loads

M. Rizwan,M.T.A. Chaudhary,M. Ilyas,Raja Rizwan Hussain,T.R. Stacey 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.2

Cyclic test of the columns is of practical relevance to the performance of compression members during an earthquake loading. The strength, ductility and energy absorption capabilities of reinforced concrete (RC) columns subjected to cyclic loading have been estimated by many researchers. These characteristics are not normally inherent in plain concrete but can be achieved by effectively confining columns through transverse reinforcement. An extensive experimental program, in which performance of four RC columns detailed according to provisions of ACI-318-08 was studied in contrast with that of four columns confined by a new proposed technique. This paper presents performance of columns reinforced by standard detailing and cast with 25 and 32 MPa concrete. The experimentally achieved load-displacement hysteresis and backbone curves of two columns are presented. The two approaches which work in conjunction with Response 2000 have been suggested to draw analytical back bone curves of RC columns. The experimental and analytical backbone curves are found in good agreement. This investigation gives a detail insight of the response of RC columns subjected to cyclic loads during their service life. The suggested analytical procedures will be available to the engineers involved in design to appraise the capacity of RC columns.

Effect of Annealing on the Conversion of ZnS to ZnO Nanoparticles Synthesized by the Sol-gel Method Using Zinc Acetate and Thiourea

Rizwan Wahab,S. G. Ansari,김영순,M. S. Dhage,서형기,송민우,신형식 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.3

A systematic study is presented on the conversion of zinc sulfide to zinc oxide nanoparticles as a function of annealing temperature. Zinc acetate dihydrate (Zn(CH3COO)2.2H2O) and thiourea (NH2CSNH2) are used as precursors to synthesize ZnS and then ZnO. The aqueous solution of the precursor was refluxed at 90 °C for over 12 h. The synthesized complex was then annealed at 300 °C, 500 °C, 700 °C, and 900 °C in air for one hour. From elemental analyses, it was found that the as-synthesized powder is a mixture of ZnS and ZnO, which annealing later converts to the zinc oxide phase only. The morphological observations revealed spherical particles of various sizes (20 nm to 300 nm) while increasing the annealing temperatures. A drastic change in the vibration bands is noticed with annealing. Photoelectron peaks related to sulfur and carbon are observed for synthesized powder, whereas, these peaks disappeared when annealed at 500 °C. A systematic study is presented on the conversion of zinc sulfide to zinc oxide nanoparticles as a function of annealing temperature. Zinc acetate dihydrate (Zn(CH3COO)2.2H2O) and thiourea (NH2CSNH2) are used as precursors to synthesize ZnS and then ZnO. The aqueous solution of the precursor was refluxed at 90 °C for over 12 h. The synthesized complex was then annealed at 300 °C, 500 °C, 700 °C, and 900 °C in air for one hour. From elemental analyses, it was found that the as-synthesized powder is a mixture of ZnS and ZnO, which annealing later converts to the zinc oxide phase only. The morphological observations revealed spherical particles of various sizes (20 nm to 300 nm) while increasing the annealing temperatures. A drastic change in the vibration bands is noticed with annealing. Photoelectron peaks related to sulfur and carbon are observed for synthesized powder, whereas, these peaks disappeared when annealed at 500 °C.

Effect of As-Mold Rapid Cooling of Core Region on Shrinkage & Crystallinity of Injection Molded Parts Using Microcellular Foaming Process

Rizwan Zafar,차성운(Cha Sung Woon) 한국정밀공학회 2008 한국정밀공학회 학술발표대회 논문집 Vol.2008 No.6월

Effect of Refluxing Time on the Morphology of Pencil like Zinc Oxide Nanostructures Prepared by Solution Method

Rizwan Wahab,김영순,신형식 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.5

This paper presents the fabrication of pencil like zinc oxide nanorods by solution method using precursor zinc acetate di-hydrate (Zn(Ac)2.2H2O) and alkali sodium hydroxide (NaOH) at a very low refluxing temperature (75 °C) for different ageing/ refluxing (12 h, 24 h, 36 h, 48 h and 60 h) time intervals. The morphological observation was carried out by using Field Emission Scanning Electron Microscopy (FESEM). The FESEM revealed that as the aging/refluxing time increased, the size (length and diameter) of the zinc oxide nanorods also increased. Furthermore, the morphology and crystallinity of the products grown were also confirmed by Transmission Electron Microscopy (TEM), high-resolution TEM, and Selected Area Electron Diffraction (SAED) patterns, which indicated that grown pencils grew along a [0001] direction with an ideal lattice fringe distance of ~0.52 nm. The optical properties of the grown pencil-like zinc oxide nanorods were characterized by using UV-vis spectroscopy. Strong absorbance peaks were observed at ~375 nm to 378 nm,which is the characteristic peak for the wurtzite hexagonal phase of ZnO. The FTIR spectroscopic measurement showed a standard peak of zinc oxide in the range of 428 cm−1to 520 cm−1. Additionally, on the basis of chemical and morphological analysis, we have also proposed a possible growth mechanism for pencillike zinc oxide nanostructures.

Experimental Investigation of Laser Assisted Machining of AZ91 Magnesium Alloy

Rizwan Abdul Rahman Rashid,Gui Wang,Shoujin Sun,Matthew Simon Dargusch 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

The demand for magnesium alloys has been increasing over the past decade due to the push towards weight reduction in fuel efficient automobiles, cheap electronics, and biodegradable medical implants. However, magnesium has limited deformation systems available as a result of its HCP crystal structure which makes plastic deformation difficult. In this research, a laser is applied to heat the surface of the AZ91 magnesium alloy to activate additional deformation systems and reduce the cutting forces during machining. It has been shown that both the main cutting force and the feed force are reduced during laser assisted machining when compared with conventional (un-assisted) machining.

Experimental study of surface wettability and electric field effect on liquid flow

Rizwan Ul Hassan,Jaehyun Lee,Doyoung Byun 한국가시화정보학회 2020 한국가시화정보학회 학술발표대회 논문집 Vol.2020 No.11

Effect of metal and metal oxide nanoparticles on growth and physiology of globally important food crops: A critical review

Rizwan, Muhammad,Ali, Shafaqat,Qayyum, Muhammad Farooq,Ok, Yong Sik,Adrees, Muhammad,Ibrahim, Muhammad,Zia-ur-Rehman, Muhammad,Farid, Mujahid,Abbas, Farhat Elsevier 2017 Journal of hazardous materials Vol.322 No.1

<P><B>Abstract</B></P> <P>The concentrations of engineered metal and metal oxide nanoparticles (NPs) have increased in the environment due to increasing demand of NPs based products. This is causing a major concern for sustainable agriculture. This review presents the effects of NPs on agricultural crops at biochemical, physiological and molecular levels. Numerous studies showed that metal and metal oxide NPs affected the growth, yield and quality of important agricultural crops. The NPs altered mineral nutrition, photosynthesis and caused oxidative stress and induced genotoxicity in crops. The activities of antioxidant enzymes increased at low NPs toxicity while decreased at higher NPs toxicity in crops. Due to exposure of crop plants to NPs, the concentration of NPs increased in different plant parts including fruits and grains which could transfer to the food chain and pose a threat to human health. In conclusion, most of the NPs have both positive and negative effects on crops at physiological, morphological, biochemical and molecular levels. The effects of NPs on crop plants vary greatly with plant species, growth stages, growth conditions, method, dose, and duration of NPs exposure along with other factors. Further research orientation is also discussed in this review article.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metal and metal oxide nanoparticles (NPs) are widely used worldwide. </LI> <LI> NPs has both positive and negative effects of crop plants. </LI> <LI> NPs toxicity decreased growth, biomass and yield of food crops. </LI> <LI> This review discussed the NPs effects and toxicity mechanisms in food crops. </LI> </UL> </P>

Novel Bipolar Soft Rough-Set Approximations and Their Application in Solving Decision-Making Problems

Rizwan Gul 한국지능시스템학회 2022 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.22 No.3

The rough set (RS) theory is a successful approach for studying the uncertainty in data. Incontrast, the bipolar soft sets (BSS) can deal with the uncertainty, as well as bipolarity ofthe data in many situations. In 2018, Karaaslan and C¸ agman proposed bipolar soft rough ˘sets (BSRSs), a hybridization of RS and BSS. However, certain shortcomings with BSRSviolate Pawlak’s RS theory. To overcome these shortcomings, the concept of the modifiedbipolar soft rough set (MBSRS) has been proposed in this study. Moreover, this idea hasbeen investigated through illustrative examples, where the important properties are inspecteddeeply. Furthermore, certain significant measures associated with MBSRS are also provided. Finally, an application of the MBSRS to multi-attribute group decision-making (MAGDM)problems is proposed. In addition, among various alternatives, an algorithm for decisionmaking accompanied by a practical example is presented as the optimal alternative . A briefcomparative analysis of the proposed approach with some existing techniques is also providedto indicate the validity, flexibility, and superiority of the suggested MAGDM model.

Online Condition Monitoring and Leakage Current Effect Based on Local Area Environment

Rizwan Ahmed,김태용,이윤정,전성호,이준신,최인혁,손주암,구자빈 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.2

High voltage outdoor insulator plays a pivotal role in safety and reliability of power transmission system.Contamination severely infl uences the performance of outdoor insulator. To asses contamination severity on insulator surface and to predict flashovers, leakage current monitoring is required. The amount of leakage current fl owing on the surface of insulator indicates insulation safety. Increase in leakage current generates high voltage peaks at insulator dead ends. The voltage may be as high as 1000–5000 volts, mainly depends on certain weather conditions, results in enormous amount of power losses and threat to public safety. The insulator performance depends on amount and type of pollution and wetting mechanism. Leakage current is important tool to investigate insulator electrical surface activity. The scope of this paper is to review leakage current effect based on local area conditions. Leakage current importance for insulators and different techniques used to measure leakage current in lab and at fi eld, special focus on online leakage current monitoring.