RC 보의 프리텐션 보강 효과 검증을 위한 실험체 설계 및 제작

서동우 ( Seo¸ Dong-woo ),정규산 ( Jung¸ Kyu-san ),김건수 ( Kim¸ Kun-soo ) 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.24 No.2

본 연구는 기존 포스트텐션(외부강선) 공법이 갖는 문제점(예: 정착구 힘의 집중, 외부 돌출된 보강재의 지속적인 관리 등)들을 극복하고 보다 발전된 구조형식을 적용하고자 하였다. 노후화된 콘크리트 구조물을 대상으로 긴장재의 프리텐션을 이용하여 보수·보강이 동시에 가능하며, 우수한 미관을 제공하는 신개념의 시공 기술을 개발하고 성능을 평가하고자 한다. 본 기술은 기존 유지관리 공법들이 갖는 한계와 문제점을 극복하고 보다 효율적인 구조물 성능향상 공법을 개발하고자 한다. 또한, 본 기술은 노후된 콘크리트 거더교를 주 보강 대상으로 하지만, 인장 또는 전단균열이 발생한 벽체와 곡선 표면을 가진 콘크리트 구조물 등 대부분의 노후 콘크리트 보강에 적용 가능하고, 보강성능도 우수할 것으로 예상된다.

Specificational Pseudoclefts and a Negative Sensitive Item Connectivity Effect

Dongwoo Park(Dongwoo Park) 한국생성문법학회 2023 생성문법연구 Vol.33 No.1

A negative sensitive item (NSI) connectivity effect shown in specificational pseudoclefts refers to a phenomenon where the NSI pivot can be licensed by the negation marker in the presupposition CP, even though the pivot is not in the scope of the negation marker in narrow syntax. English specificational pseudoclefts exhibit this connectivity effect, while Korean ones do not. In this squib, I argue that this contrast is attributable to the difference in characteristics of NSIs between the two languages, and that the breakdown of the NSI connectivity effect in Korean is induced by the semantic/pragmatic requirements imposed on specificational pseudoclefts.

Possibility of Carbon Dioxide Conversion Using Seawater through Aqueous Approach

( Dongwoo Kang ),( Min-gu Lee ),( Hyungbae Gil ),( Eunjung Kim ),( Jinwon Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2014 한국폐기물자원순환학회 추계학술발표논문집 Vol.2014 No.-

The amount of carbon dioxide emission is continuously increasing and many researchers are concerned about climate change caused by its emission. Hence, some technologies which can reduce its emission have been developed and commercialized in many industries. These technologies are commonly called Carbon Capture and Storage (CCS) technology. In conventional CCS technology, carbon dioxide gas produced from industrial processes was usually captured by basic liquid absorbent such as monoethanolamine(MEA) and so on. After it is captured by those absorbents, they was flown to desorption step and was compressed at high pressure and transported to suitable places such as deep ocean or deep underground. However, there exist some problems when carbon dioxide is stored in such places. For instance, leak into the atmosphere can occur. Also, some nations including Korea may have difficulty finding suitable places for its storage since area of the nations is not that large and the ground is not stable. So, the method that can utilize captured carbon dioxide has been developed. When carbon dioxide is combined with metal cation such as calcium ion, it becomes calcium carbonate (CaCO3) which can be used for various purposes like construction materials, pharmaceutical manufacture, additives and so on. This is called Carbon Capture and Utilization (CCU) technology. In this research, seawater was used to supply calcium ions. There contained much amount of calcium component in seawater and amount of seawater is virtually limitless. MEA was used as absorbents and saturated by simulated flue gas. Pretreated seawater was then added to saturated absorbent. When carbon dioxide gas is dissolved to MEA, it exist in forms of ions and they can easily produce precipitated calcium carbonate (PCC) salts by reacting with calcium ions contained in seawater.

Exploring the Role of User-Driven Communities in NFT Valuation: A Case Study of Discord

Dongwoo Kim,Min Jae Lee,기우석,김동환 한국멀티미디어학회 2022 The journal of multimedia information system Vol.9 No.4

There has been a recent increase in interest in NFTs, as the number of high-priced trades has risen. While some research attempts to identify the factors behind these value spikes using traditional market analysis and machine learning, few studies focus on the user-driven communities where vast amounts of information are shared. We aim to address the need for understanding the factors that influence NFT prices within user-driven communities, specifically within Discord, an influential platform for NFT projects. To do this, three NFT projects are selected - Coolman's Universe, Degen Toonz, and Mfer - based on their size, value, and active user base. Chat data are collected from these projects, and three methods are used to gain insights into how communication among users evolves around influential Discourse leaders. The analysis shows that there are distinct ways and styles in which discourse leaders communicate with community members. Furthermore, the common sentimental experience of the leaders regarding the project value is identified to highlight the important aspects of communities. Conducting a social network analysis to examine the leader's significance within the community enables us to take the initial step towards comprehending the value of an NFT from the perspective of a user-driven community.

A Study on the Design Technology of Permanent Magnet Synchronous Motor Considering the Characteristics of Electric Vehicle and Recent Trend of Motor Technology

Dongwoo Kang 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.32 No.2

Radially patterned polycaprolactone nanofibers as an active wound dressing agent

Dongwoo Shin,Min Sup Kim,양채은,이원재,노태석,백우열 대한성형외과학회 2019 Archives of Plastic Surgery Vol.46 No.5

Background The objectives of this study were to design polycaprolactone nanofibers with a radial pattern using a modified electrospinning method and to evaluate the effect of radial nanofiber deposition on mechanical and biological properties compared to non-patterned samples. Methods Radially patterned polycaprolactone nanofibers were prepared with a modified electrospinning method and compared with randomly deposited nanofibers. The surface morphology of samples was observed under scanning electron microscopy (SEM). The tensile properties of nanofibrous mats were measured using a tabletop uniaxial testing machine. Fluorescence-stained human bone marrow stem cells were placed along the perimeter of the radially patterned and randomly deposited. Their migration toward the center was observed on days 1, 4, and 7, and quantitatively measured using ImageJ software. Results Overall, there were no statistically significant differences in mechanical properties between the two types of polycaprolactone nanofibrous mats. SEM images of the obtained samples suggested that the directionality of the nanofibers was toward the central area, regardless of where the nanofibers were located throughout the entire sample. Florescence images showed stronger fluorescence inside the circle in radially aligned nanofibers, with significant differences on days 4 and 7, indicating that migration was quicker along radially aligned nanofibers than along randomly deposited nanofibers. Conclusions In this study, we successfully used modified electrospinning to fabricate radially aligned nanofibers with similar mechanical properties to those of conventional randomly aligned nanofibers. In addition, we observed faster migration along radially aligned nanofibers than along randomly deposited nanofibers. Collectively, the radially aligned nanofibers may have the potential for tissue regeneration in combination with stem cells.

Outage Probability for Dual-Hop Relaying Systems With Multiple Interferers Over Rayleigh Fading Channels

Dongwoo Lee,Jae Hong Lee IEEE 2011 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.60 No.1

<P>In this paper, we analyze the dual-hop amplify-and-forward (AF) and decode-and-forward (DF) relaying systems with multiple interferers over Rayleigh fading channels. We derive closed-form expressions for the outage probability of the dual-hop AF and DF relaying systems with multiple interferers, which have arbitrary transmit power. Numerical results verify the validity of our theoretical analysis by comparison with Monte Carlo simulations and compare the outage probabilities of the dual-hop AF and DF relaying systems with multiple interferers.</P>

Pyrolytic Jetting of Highly Porous Laser-Induced Graphene Fiber for Cost-Effective Supercapacitor

Dongwoo Kim,Hyunkoo Lee,Eunseung Hwang,Sukjoon Hong,Habeom Lee 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.2

The recently reported laser pyrolytic jetting process enables facile generation of highly porous, free-standing graphene fiber from polyimide film upon the scanning of tightly focused continuous-wave laser. As a follow-up study, we claim that the corresponding laser pyrolytic jetting process is favorable for the fabrication of relevant energy device applications compared to the conventional LIG process in both energy-saving and material-saving perspectives. Moreover, the volume of the pyrolysis product is substantially increased in the case of pyrolytic jetting compared to conventional LIG, resulting in an extended surface area for storing more electric charges. At the same time, material characterization by Raman measurement validates that the exfoliated product from pyrolytic jetting is analogous to the conventional LIG and therefore suitable for supercapacitor application. As a result, supercapacitor created by the pyrolytic jetting allows substantial enhancement in the capacitance compared to the conventional LIG for both with and without manganese oxide layer coating, proposing the potential of pyrolytic jetting for the efficient fabrication of carbon-based energy devices.

Design of an Elliptical Orbit for High-Resolution Optical Observation at a Very Low Altitude over the Korean Peninsula

Dongwoo Kim,Taejin Chung The Korean Space Science Society 2023 Journal of Astronomy and Space Sciences Vol.40 No.1

Surveillance and reconnaissance intelligence in the space domain will become increasingly important in future battlefield environments. Moreover, to assimilate the military provocations and trends of hostile countries, imagery intelligence of the highest possible resolution is required. There are many methods for improving the resolution of optical satellites when observing the ground, such as designing satellite optical systems with a larger diameter and lowering the operating altitude. In this paper, we propose a method for improving ground observation resolution by using an optical system for a previously designed low orbit satellite and lowering the operating altitude of the satellite. When the altitude of a satellite is reduced in a circular orbit, a large amount of thrust fuel is required to maintain altitude because the satellite's altitude can decrease rapidly due to atmospheric drag. However, by using the critical inclination, which can fix the position of the perigee in an elliptical orbit to the observation area, the operating altitude of the satellite can be reduced using less fuel compared to a circular orbit. This method makes it possible to obtain a similar observational resolution of a medium-sized satellite with the same weight and volume as a small satellite. In addition, this method has the advantage of reducing development and launch costs to that of a small-sized satellite. As a result, we designed an elliptical orbit. The perigee of the orbit is 300 km, the apogee is 8,366.52 km, and the critical inclination is 116.56°. This orbit remains at its lowest altitude to the Korean peninsula constantly with much less orbit maintenance fuel compared to the 300 km circular orbit.

Anti-Sway Control of the Overhead Crane System using HOSM Observer

Dongwoo Kwon,Myunghwan Eom,Dongkyoung Chwa 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.4

This paper proposes a sum of squares (SOS) method for anti-swing control of overhead crane system using HOSM (High-Order Sliding-Mode) observer. By representing the dynamic equations of overhead crane as the polynomial dynamic equations via Taylor series expansion, the control input is obtained from the converted polynomial dynamic equations by numerical tool SOSTOOL. Since the actual crane systems include disturbance such as wind and friction, we propose a method to compensate for the disturbance by estimating the disturbance using HOSM observer. Numerical simulations show the effectiveness and the applicability of the proposed method.