• Title/Summary/Keyword: U-slot

Search Result 112, Processing Time 0.036 seconds

Harmonic Suppression Compact Microstrip Patch Antenna for IoT Sensor (고조파 억제를 위한 IoT 센서용 소형 마이크로스트립 패치 안테나)

  • Lee, Hyun-Seung;Lim, Jeong-Taek;Jung, Bang-Chul;Kim, Choul-Young
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.6
    • /
    • pp.85-89
    • /
    • 2017
  • This paper proposes an antenna incorporating a bandstop filter to miniaturize the rectenna used for wireless power transmission with the emerging interest these days. To suppress the harmonics that can be re-radiated, this paper proposes a microstrip patch antenna that can suppress the harmonics while maintaining the size of the antenna by inserting a U-slot, which acts as a bandstop filter, on the ground plane of the antenna. As a result, S11 of the second harmonic(4.6GHz) was reduced from -5.61dB to -0.338dB and the efficiency was suppressed significantly from 29.76% to 1.5%. In addition, the maximum gain was reduced to -12dBi from 2.89dBi. On the other hand, at the fundamental frequency (2.45GHz), the S11 value was reduced from -18 dB to -15 dB, and the efficiency was reduced slightly from 68.2% to 60%. In the case of applying a microstrip antenna combined with the proposed bandstop filter to a rectenna, it is believed that the harmonics that degrade the performance of the rectenna can be removed effectively while reducing the large area occupied by harmonic suppression.

Dual Band-notched Monopole Antenna for 2.4 GHz WLAN and UWB Applications (이중대역 저지특성을 가지는 2.4 GHz WLAN 및 UWB 겸용 모노폴 안테나)

  • Lee, Ki-yong;Lee, Young-soon
    • Journal of Advanced Navigation Technology
    • /
    • v.21 no.2
    • /
    • pp.193-199
    • /
    • 2017
  • In the paper, a dual band-notched monopole antenna is proposed for 2.4 GHz WLAN (2.4 ~ 2.484 GHz) and UWB (3.1 ~ 10.6 GHz) applications. The 3.5 GHz WiMAX band notched characteristic is achived by a pair of L-shaped slots instead of the previous U-shaped slot on the center of the radiating patch, whereas the 7.5 GHz band notched characteristic is achived by C-shaped strip resonator placed near to the microstrip feed line. The measured impedance bandwidth (${\mid}S_{11}{\mid}{\leq}-10dB$) is 8.62 GHz (2.38 ~ 11 GHz) which is sufficient to cover 2.4 GHz WLAN and UWB band, while measured band-notched bandwidths for 3.5 GHz WiMAX and 7.5 GHz bnad are 1.13 GHz (3.15 ~ 4.28 GHz) and 800 MHz (7.2 ~ 8 GHz) respectively. In particular, it has been observed that antenna has a good omnidirectional radiation patterns and higher gain of 2.51 ~ 6.81 dBi over the entire frequency band of interest.

A Study on Frictioal Resistance Force of Orthodontic Resin Bracket (교정용 Resin bracket의 마찰 저항력에 관한 연구)

  • Lee, Won-you;Lim, Kyung-Soo
    • The korean journal of orthodontics
    • /
    • v.29 no.1 s.72
    • /
    • pp.107-112
    • /
    • 1999
  • As increasing number of adult patients, the esthetic orthodontic appliances are needed. They are tooth-colored or translucent ceramic and resin brackets. Although ceramic and resin bracket have good esthetics, there are some disadvantage such as frictions. Recently, metal-reinforced resin bracket(MRBB) were introduced. The purpose of this study is to find frictional force of MRRB, ceramic bracket and resin brackets. There is few study in frictional force about metal reinforced resin bracket(MRRB). This study used 4 orthodontic wire(.016 S-S, .0l6X.022 S-S, .016 $TMA^{\circledR}$, .0l7X.025 $TMA^{\circledR}$ and 5 brackets(one metal bracket, one ceramic bracket, one resin bracket, two MRRB). The following result is obtained using metal bracket(Ormco.Co., U.S.A), ceramic brackets($Crystalline^{\circledR}$), resin bracket( Clear Medium $Siamase^{\circledR}$). Following conclusions are obtained. 1. Ceramic and resin bracket have significantly more frictional forces than metal reinforced resin bracket and metal bracket. 2. There is no significant difference in frictional force according to the slot types of metal - reinforced resin brackets. 3. There is no significant difference in frictional force between metal reinforced resin bracket and metal bracket. 4.. Frictional force is decreased in S-S wire than TMA wire.

  • PDF

Ultra-Wideband Antenna Having a Frequency Band Notch Characteristic (주파수 대역 저지 특성을 갖는 초광대역 안테나)

  • Choi Woo-Young;Jung Ji-Hak;Chung Kyung-Ho;Choi Jae-Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.16 no.2 s.93
    • /
    • pp.199-203
    • /
    • 2005
  • In this paper, a novel compact and frequency band-notch antenna for Ultra-Wideband(UWB) applications is proposed. The designed antenna not only shows good impedance bandwidth for ultra-wideband but has band notch characteristic for the frequency band of $5.15\~5.825\;GHz$ limited by IEEE 802.1la and HIPERLAN/2. To achieve both properties of wide band and band notch, the techniques of a concaved ground plane and inserted U-shaped thin slot into planar radiator are used respectively. A manufactured antenna satisfied VSWR<2 for the frequency band of $2.95\~11.7\GHz$ except the limited band of $4.92\~5.866\;GHz$.

Design of partial discharge sensor in rotating machines (저.고주파용 부분방전 센서 해석 및 설계)

  • Park, Yoon-Mi;Heo, Chang-Geun;Lee, Jung-Yub;Jung, Hyun-Kyo
    • Proceedings of the KIEE Conference
    • /
    • 2005.07c
    • /
    • pp.2253-2255
    • /
    • 2005
  • 운전 중인 회전기기에서 고정자 권선의 절연 상태는 부분방전시험을 통해 검사, 평가할 수 있고 이를 통하여 사고예방을 위한 진단을 할 수 있다. 기존 센서인 SSC(Stator Slot Coupler)는 비접촉식으로 권선의 웨지 아래에 설치하므로 설치하기가 불편하고 Global VPI 방식으로 제작된 소형 회전기에는 사용할 수 없는 단점이 있다. 본 논문에서는 소형 회전기에 사용 가능한 저, 고주파용 부분방전 센서를 제안하였다. 웨지 위에 설치 가능한 SSC 형태의 마이크로스트립 센서 및 2선 평행 전송선로 센서는 고주파에 적합하고 저렴하며 소형 회전 기에 설치 가능하다. 센서의 성능을 검증하기 위해 3차원 해석 프로그램을 사용하여 좋은 전자파 검출 성능을 도출할 수 있었다. 또한 저주파용으로 제안된 U 타입 센서는 유도전류를 검출하는 센서로서 슬롯 외부에 설치되어야 하고 시간차분 수치해석을 이용해서 저주파에서 효과적으로 방전 펄스를 검출함을 확인할 수 있었다.

  • PDF

A Study on Squeal Noise Robustness Analysis to Improve Composite Brake Stability of High Performance and Eco-Friendly Vehicles (고성능 및 친환경 차량의 복합재 브레이크 안정감 향상을 위한 스퀼 노이즈 강건성 분석에 관한 연구)

  • Shim, J.H.;Lee, J.H.;Shin, U.H.;Lim, D.W.;Hyun, E.J.;Jeo, T.H.
    • Journal of Auto-vehicle Safety Association
    • /
    • v.13 no.3
    • /
    • pp.32-40
    • /
    • 2021
  • Composite material is very attractive because it has excellent mechanical property and is possible to lightweight due to the low density. However, composite material is less used compared to other systems in the chassis system because it is very hard to solve NVH problem when composite material is applied to vehicle. Especially, reducing squeal noise of composite brake system is essential to apply it to vehicle successfully. In this paper, we present a new solution to reduce squeal noise of composite brake system. To achieve this goal, we analyze main causes of noise using RCA (Root Cause Analysis), CA (Contradiction Analysis) and sequentially get IFR (Ideal Final Result) to solve the problem. Next, we define the function of composite brake system and derive control factors and noise factors. A variety of tests for factors like chamfer, slot, damping shim, underlayer of brake pad are done. In addition, we analyze level of contribution for control factors theoretically. Finally, we get the effective solution for reducing squeal noise.

A Proposal for Korean armed forces preparing toward Future war: Examine the U.S. 'Mosaic Warfare' Concept (미래전을 대비한 한국군 발전방향 제언: 미국의 모자이크전 수행개념 고찰을 통하여)

  • Chang, Jin O;Jung, Jae-young
    • Maritime Security
    • /
    • v.1 no.1
    • /
    • pp.215-240
    • /
    • 2020
  • In 2017, the U.S. DARPA coined 'mosaic warfare' as a new way of warfighting. According to the Timothy Grayson, director of DARPA's Strategic Technologies Office, mosaic warfare is a "system of system" approach to warfghting designed around compatible "tiles" of capabilities, rather than uniquely shaped "puzzle pieces" that must be fitted into a specific slot in a battle plan in order for it to work. Prior to cover mosaic warfare theory and recent development, it deals analyze its background and several premises for better understanding. The U.S. DoD officials might acknowledge the current its forces vulnerability to the China's A2/AD assets. Furthermore, the U.S. seeks to complete military superiority even in other nation's territorial domains including sea and air. Given its rapid combat restoration capability and less manpower casualty, the U.S. would be able to ready to endure war of attrition that requires massive resources. The core concept of mosaic warfare is a "decision centric warfare". To embody this idea, it create adaptability for U.S. forces and complexity or uncertainty for the enemy through the rapid composition and recomposition of a more disag g reg ated U.S. military force using human command and machine control. This allows providing more options to friendly forces and collapse adversary's OODA loop eventually. Adaptable kill web, composable force packages, A.I., and context-centric C3 architecture are crucial elements to implement and carry out mosaic warfare. Recently, CSBA showed an compelling assessment of mosaic warfare simulation. In this wargame, there was a significant differences between traditional and mosaic teams. Mosaic team was able to mount more simultaneous actions, creating additional complexity to adversaries and overwhelming their decision-making with less friendly force's human casualty. It increase the speed of the U.S. force's decision-making, enabling commanders to better employ tempo. Consequently, this article finds out and suggests implications for Korea armed forces. First of all, it needs to examine and develop 'mosaic warfare' in terms of our security circumstance. In response to future warfare, reviewing overall force structure and architecture is required which is able to compose force element regardless domain. In regards to insufficient defense resources and budget, "choice" and "concentration" are also essential. It needs to have eyes on the neighboring countries' development of future war concept carefully.

  • PDF

Analysis of a T-Shaped UWB Printed Monopole Antenna Using Surface Currents (표면 전류 분포를 이용한 T자형 UWB 평면형 모노폴 안테나 해석)

  • Lee Dong-Hyun;Park Wee-Sang
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.16 no.9 s.100
    • /
    • pp.883-892
    • /
    • 2005
  • We propose a T-shaped UWB printed monopole antenna and investigate the effect of the surface currents of the radiator and ground plane. The measured impedance bandwidth of the antenna covers the range of 3.1 to 11 GHz for a VSWR$\le$2, which satisfies the requirement of the UWB operation. From the analysis of the surface currents, the proposed antenna can be treated as two asymmetric dipoles with the included angle of 90 degrees which lie along z-direction symmetrically. It is observed that the effect of the surface currents on the radiation patterns is similar to that of the corresponding dipole. The length and width of the found plane correspond the radius and length of the dipole respectively. This approach is also valid to general printed monopole antennas. Finally, we included an antenna example having resonance at a lower frequency by tapering the edges of the ground plane and another example having a bandstop characteristic by inserting an inverted-U slot on the radiator, and explain those antennas using the surface currents.

Performance Analysis of CDMA Reservation ALOHA for Multi-traffic Services (다중 트랙픽 지원을 위한 CDMA 예약 ALOHA 방안의 성능 분석)

  • Jo, Chun Geun;Heo, Gyeong Mu;Lee, Yeon U;Cha, Gyun Hyeon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.24 no.12A
    • /
    • pp.1852-1861
    • /
    • 1999
  • In this paper, CDMA Reservation ALOHA scheme which can reduce multiple access interference and packet collision is proposed to support multi-traffic such as voice and random data with and without priority. In this scheme, the time slot is divided into two stage, access and transmission stage. Only packets with spreading codes assigned from base station in access stage can transmit their packets in transmission stage, so MAI can be reduced. To reduce packer collision in access stage, the code reservation and access permission probability are used. Code reservation is allowed for voice traffic and continuous traffic with priority using piggyback and access permission probability based on the estimation of the number of contending users in the steady-state is adaptively applied to each traffic terminal. Also, we analyzed and simulated the numerical performances required for each traffic using Markov chain modeling in a single cell environment.

  • PDF

Evaluation on the Efficiencies of Local Exhaust Systems and Airborne Concentrations of Total Chromium, Hexa-valent Chromium and Nickel in Some Electroplating Plants (일부 영세 도금사업장의 국소배기성능과 공기중 총크롬, 6가 크롬 및 니켈농도와의 관계분석)

  • Park, D.U.;Park, D.Y.;Shin, Y.C.;Oh, S.M.;Chung, K.C.
    • Journal of Korean Society of Occupational and Environmental Hygiene
    • /
    • v.3 no.1
    • /
    • pp.68-77
    • /
    • 1993
  • To evaluate efficiencies of the local exhaust systems installed in chromiun and nickel eletroplating tanks, specifications of each tank and general performances of the local exhaust systems were measured in 16 electroplating plants from July 3 to November 24, 1992. Airborne concentrations of total chromium, hexa-chromium and nickel were also measured, Most of the local exhaust systems installed in electroplating plants were inadequately designed. Average capture velocities of local exhaust systems in chromium and nickel tanks were 0.45 m/sec and 0.29 m/sec. Average slot velocities in chromium and nickel tanks were 7.30 m/sec and 2.87 m/sec repectively. Both average capture and solt velocities were in noncompliance with the standards recommened by American Conference of Governmental Industrial Hygienists (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), Exhausted air volume was insufficient in all local exhaust systems surveyed. Worker exposure levels to total chromium, hexa-chromium and nickel were $43.0{\mu}g/m^3$, $1.7{\mu}g/m^3$ and $9.3{\mu}g/m^3$, which were below the Korean Standard and U.S. Occupational Health and Safety Administration (OHSA) Permissible Exposure Limit(REL). However, Worker exposure level to hexa-chromium exceeded the NIOSH Recommended Exposure Limit(REL) of $1{\mu}g/m^3$. As the result of Scheffee's multiple comparions, worker exposure levels to all metals were significantly different between two groups by the management state of existing local exhaust systems (p<0.05). However, Difference between a group with local exhaust systems which were poorly managed and another group without local exhaust system was satatistically non-significant.

  • PDF