• Title/Summary/Keyword: Modified FR-4

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CLINICAL APPLICATION OF MODIFIED FR-4 (Modified FR-4의 임상적용례)

  • Song, Jae-Hyuk;Lee, Keung-Ho;Choi, Yeong-Chul
    • Journal of the korean academy of Pediatric Dentistry
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    • v.28 no.2
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    • pp.323-328
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    • 2001
  • Anterior open bite is one in which the teeth in the anterior portion of the maxilla and mandible are vertically apart and lack the overlapping necessary for the incisive function when the mandible is in closed position. Anterior open bite is a result of the interaction of many different etiologic factors including thumb and finger sucking, lip and tongue habits, airway obstruction, skeletal growth abnormalities and its tendency may appear with any type of skeletal patterns, such as Class I, II or III malocclusion types. Though the treatment methods for anterior open bite are various, the conventional FR-4, designed by Rolf Fr$\"{a}$nkel, is known to be effective in treating open bite cases with Class I or II skeletal patterns. It is due to that an incidence of skeletal Class II is high in the Occidentals, and open bite is accompanied by these malocclusion type in many cases. However, an incidence of skeletal Class III is high in the Orientals, and open bite is sometimes accompanied by skeletal Class III in many cases. Although the use of the conventional FR-4 was effective in the treatment of open bite, skeletal Class III would be worsened. So, a modified FR-4(placing the labial bow in the lower, the labial pads in the upper) was designed for the treatment of patients showing skeletal Class III and open bite.

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Assessing landslide susceptibility along the Halong - Vandon expressway in Quang Ninh province, Vietnam: A comprehensive approach integrating GIS and various methods

  • Nguyen-Vu Luat;Tuan-Nghia Do;Lan Chau Nguyen;Nguyen Trung Kien
    • Geomechanics and Engineering
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    • v.37 no.2
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    • pp.135-147
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    • 2024
  • A GIS-based landslide susceptibility mapping (LSM) was carried out using frequency ratio (FR), modified frequency ratio (M-FR), analytic hierarchy process (AHP), and modified analytic hierarchy process (M-AHP) methods to identify and delineate the potential failure zones along the Halong - Vandon expressway. The thematic layers of various landslide causative factors were generated for modeling in GIS, including geology, rainfall, distance to fault, distance to road, slope, aspect, landuse, density of landslide, vertical relief, and horizontal relief. In addition, a landslide inventory along the road network was prepared using data provided by the management department during the course of construction and operation from 2017 to 2019, when many landslides were documented. The validation results showed that the M-FR method had the highest AUC value (AUC = 0.971), which was followed by the FR method with AUC = 0.961. The AUC values were 0.939 and 0.892 for the M-AHP and AHP methods, respectively. The generated LSM obtained from M-FR method classified the study area into five susceptibility classes: very low (0), low (0-1), moderate (1-2), high (2-3), and very high (3-4) classes, which could be useful for various stakeholders like planners, engineers, designers, and local public for future construction and maintenance in the study area.

Design and Fabrication of Miniaturized Chipless RFID Tag Using Modified Bent H-shaped Slot (변형된 구부러진 H-모양 슬롯을 이용한 소형 Chipless RFID 태그 설계 및 제작)

  • Junho Yeo;Jong-Ig Lee
    • Journal of Advanced Navigation Technology
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    • v.27 no.6
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    • pp.815-820
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    • 2023
  • In this paper, the design method of a miniaturized chipless RFID tag using a modified bent H-shaped slot was proposed. The proposed modified bent H-shaped slot was appended on the rectangular conductor plate printed on one side of a 20 mm × 50 mm FR4 substrate with a thickness of 0.8 mm. The resonant dip frequency of the bistatic RCS for the proposed modified bent H-shaped slot was compared with the cases when the H-shaped, U-shaped slot, and bent H-shaped slots were added, respectively, on the conductor plate. The simulated resonant dip frequencies for H-shaped, U-shaped, and bent H-shaped slots were 5.907 GHz, 4.918 GHz, and 4.364 GHz, respectively. When the proposed modified bent H-shaped slot was added, the resonant dip frequency was decreased to 3.741 GHz, and, therefore, the slot length was reduced by 36.7% compared to the H-shaped slot case. Experiment results show that the resonant dip frequency of the fabricated modified bent H-shaped slot was 3.9 GHz.

Design of a broadband half bow-tie dipole antenna for digital TV Reception (디지털 TV 수신용 광대역 반 보우타이 다이폴 안테나 설계)

  • Lee, Jong-Ig;Yeo, Junho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.05a
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    • pp.61-62
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    • 2013
  • In this paper, a design method for a compact broadband planar dipole antenna fed by a microstrip (MS) line is studied. The proposed broadband dipole is optimized for terrestrial digital television (DTV) receiving. The dipole is fed by an MS line with 75-ohm characteristic impedance on an FR4 substrate and its size is $90mm{\times}180mm$. The dipole is modified to half bow-tie type for size reduction. A simplified balun is adopted for the impedance matching between the MS line and coplanar strip which feeds the dipole. The optimized dipole antenna for DTV band (470-806 MHz) is fabricated on an FR4 substrate and tested experimentally to verify the results of this study.

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Reducing the Scan Time in Gastric Emptying Scintigraphy by Using Mathematical Models (위배출 신티그래피에서 수학적 모델을 이용한 지연영상 시간의 단축)

  • Yoon, Min-Ki;Hwang, Kyung-Hoon;Choe, Won-Sick;Lee, Byeong-Il;Lee, Jae-Sung
    • The Korean Journal of Nuclear Medicine
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    • v.39 no.4
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    • pp.257-262
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    • 2005
  • Purpose: Gastric emptying scan (GES) is usually acquired up to 2 hours. Our study investigated whether a fraction of meal-retention in the stomach at 120 minutes (FR120) was predicted from the data measured for 90 minutes by using non-linear curve fitting. We aimed at saving the delayed imaging by utilizing mathematical models. Materials and Methods: Ninety-six patients underwent GES immediately after taking a boiled egg with 74 MBq (2 mCi) Tc-99m DTPA. The patients were divided into Group I ($T_{1/2}\;{\leq}90\;min$) and Group II ($90\;min). Group I (n=51) had 21 men and 30 women, and Group II (n=45) 15 men and 30 women. There was no significant difference in age and sex between the two groups. Simple exponential, power exponential, and modified power exponential curves were acquired from the measured fraction of meal-retention at each time (0, 15, 30, 45, 60, 75, and 90 min) by non-linear curve fitting ($MATLAB^{\circledR}$ 5.3) and another simple exponential fitting was performed on the fractions at late times (60, 75, and 90 min). A predicted FR120 was calculated from the acquired functional formulas. A correlation coefficient between the measured FR120 and the predicted FR120 was computed ($MedCalc^{\circledR}$ 6.0). Results: Correlation coefficients(r) between the measured FR120 and the predicted FR120 of each mathematical functions were as follows: simple exponential function (Group I: 0.8558, Group II: 0.5982, p<0.0001), power exponential function (Group I: 0.8755, Group II: 0.6008, p<0.0001), modified power exponential function (Group I: 0.8892, Group II: 0.5882, p<0.0001), and simple exponential function at the late times(Group I: 0.9085, Group II: 0.6832, p<0.0001). In all the fitting models, the predicted FR120 were significantly correlated with the measured FR120 in Group I but not in Group II. There was no statistically significant difference in correlation among the 4 mathematical models. Conclusion: In the cases with $T_{1/2}\;{\leq}90\;min$, the predicted FR120 is significantly correlated with the measured FR120. Therefore, FR120 can be predicted from the data measured for 90 minutes by using non-linear curve fitting, saving the delayed imaging after 90 minutes when $T_{1/2}\;{\leq}90\;min$ is ascertained.

A Design and Manufacture of Modified Rhombus Slot UWB antenna with Fork-shaped-Feedline (포크 모양의 급전 구조를 갖는 변형된 마름모 슬롯 UWB 안테나 설계 및 제작)

  • Ha, Sung-Jea;Yoon, Joong-Han
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.7
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    • pp.1221-1228
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    • 2016
  • In this paper, we propose a modified rhombus slot UWB(Ultra Wide Band) antenna with fork-shaped feeding structure. The proposed antenna is modified rhombus slot structure and fork-shaped feeding structure to get ultra-wideband characteristics for UWB communication. Modified rhombus slot structure consists of slot shaped which eliminated upper and lower part of the basic rhombus slot. The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.4, and its overall size is $34mm(W_1){\times}34mm(L_1){\times}1mm(t)$, and its slot antenna size is $30mm(W_2){\times}16.75mm(L_3+L_4)$. After carrying out the simulation of each parameters, optimized values are obtained. From the fabricated and measured results, return loss of the proposed antenna satisfied Return Loss -10dB in 3.1 ~ 10.6 GHz. And measured results of gain and radiation patterns characteristics displayed for operating bands.

Bandwidth Enhancement of Double-Dipole Quasi-Yagi Antenna Using Modified Microstrip-to-Coplanar Strip line Balun (변형된 마이크로스트립-동일면 스트립 선로 밸런을 이용한 이중 다이폴 준-야기 안테나의 대역폭 향상)

  • Yeo, Junho;Lee, Jong-Ig;Baek, Woon-Seok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.3
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    • pp.457-463
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    • 2016
  • In this paper, a method of enhancing the bandwidth of a double-dipole quasi-Yagi antenna (DDQYA) using a modified integrated balun is presented. The modified integrated balun consists of a microstrip (MS) line inserted along the center of a coplanar strip (CPS) line and the end of the MS line is connected to the CPS line through a shorting pin at the feed point. The geometry of the modified integrated balun is adjusted to improve the bandwidth of the DDQYA. In addition, the performance of the proposed balun in a back-to-back configuration is compared with a conventional balun. The proposed antenna with the optimized modified integrated balun is fabricated on an FR4 substrate, and the experiment results show that the antenna has a frequency band of 1.56-3.04 GHz(64.4%) for a VSWR < 2, which shows enhanced bandwidth compared to the DDQYA with the conventional balun.

Removal of Methyl tert-Butyl Ether (MTBE) by Modified Fenton Process for in-situ Remediation (Methyl tert-Butyl Ether(MTBE)의 in-situ Remediation을 위한 Modified Fenton Process에 관한 연구)

  • Chung, Young-Wook;Seo, Seung-Won;Kim, Min-Kyoung;Lee, Jong-Yeol;Kong, Sung-Ho
    • Journal of Soil and Groundwater Environment
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    • v.12 no.2
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    • pp.27-36
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    • 2007
  • A recent study showed that MTBE can be degraded by Fenton's Reagent (FR). The treatment of MTBE with FR, however, has a definite limitation of extremely low pH requirement (optimum pH $3{\sim}4$) that makes the process impracticable under neutral pH condition on which the ferrous ion precipitate forming salt with hydroxyl anion, which result in the diminishment of the Fenton reaction and incompatible with biological treatment. Consequently, this process using only FR is not suitable for in-situ remediation of MTBE. In order to overcome this limitation, modified Fenton process using NTA, oxalate, and acetate as chelating reagents was introduced into this study. Modified Fenton reaction, available at near neutral pH, has been researched for the purpose of obtaining high performance of oxidation efficiency with stabilized ferrous or ferric ion by chelating agent. In the MTBE degradation experiment with modified Fenton reaction, it was observed that this reaction was influenced by some factors such as concentrations of ferric ion, hydrogen peroxide, and each chelating agent and pH. Six potential chelators including oxalate, succinate, acetate, citrate, NTA, and EDTA were tested to identify an appropriate chelator. Among them, oxalate, acetate, and NTA were selected based on their remediation efficiency and biodegradability of each chelator. Using NTA, the best result was obtained, showing more than 99.9% of MTBE degradation after 30 min at pH 7; the initial concentration of hydrogen peroxide, NTA, and ferric ion were 1470 mM, 6 mM, and 2 mM, respectively. Under the same experimental condition, the removal of MTBE using oxalate and acetate were 91.3% and 75.8%, respectively. Optimum concentration of iron ion were 3 mM using oxalate which showed the greatest removal efficiency. In case of acetate, $[MTBE]_0$ decreased gradually when concentration of iron ion increased above 5 mM. In this research, it was showed that modified Fenton reaction is proper for in-situ remediation of MTBE with great efficiency and the application of chelatimg agents, such as NTA, was able to make the ferric ion stable even at near neutral pH. In consequence, the outcomes of this study clearly showed that the modified Fenton process successfully coped with the limitation of the low pH requirement. Furthermore, the introduction of low molecular weight organic acids makes the process more available since these compounds have distinguishable biodegradability and it may be able to use natural iron mineral as catalyst for in situ remediation, so as to produce hydroxyl radical without the additional injection of ferric ion.

A Design for a Modified Circular Slot Antenna with a Fork-like Tuning Stub for UWB Operations

  • Yoon, Joong-Han
    • Journal of information and communication convergence engineering
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    • v.14 no.2
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    • pp.65-70
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    • 2016
  • This paper proposes and experimentally tests a modified circular slot antenna fed by a fork-like tuning stub for ultra-wideband (UWB) operation. The proposed antenna consists of a modified circular slot model and fork-like tuning stub. The proposed antenna is printed on a 34.0 mm × 30.0 mm FR4 substrate with thickness of 1.0 mm and relative permittivity of 4.4. The effect of various parameters of the circular slot and fork-like tuning stub is investigated for UWB operation. The modified circular slot and fork-like tuning stub are fabricated on the substrate to achieve wideband operation and good impedance matching. Experimental results demonstrated that the measured return loss exhibits an acceptable agreement with the simulated return loss and satisfies the -10 dB impedance bandwidth requirement while simultaneously covering the UWB bands. In addition, the proposed antenna shows good radiation characteristics and gains in the UWB bands.

A Design and Manufacture of Modified Rhombus Slot UWB antenna with Fork-shaped-Fed (포크 모양의 급전 구조를 갖는 변형된 마름모 슬롯 UWB 안테나 설계 및 제작)

  • Kim, Jong-Hwa;Kim, Gi-Rae;Yoon, Joong-Han
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.05a
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    • pp.630-632
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    • 2016
  • In this paper, we propose a modified rhombus slot UWB(Ultra Wide Band) antenna with fork-shaped feeding structure. The proposed modified rhombus slot structure is eliminated upper and lower part of the basic rhombus slot shape to get ultra-wideband characteristics for UWB communication. Also, feeding structure is used to fork-shaped structure to get ultra-wideband characteristics. The antenna is designed on an FR-4 substrate of which the dielectric constant is 4.4, and its overall size is $34mm(W1){\times}34mm(L1){\times}1mm(t)$, and its slot antenna size is $30mm(W2){\times}16.75mm(L3+L4)$. After the optimized process, the proposed antenna is fabricated and measured. Measured result. fabricated antenna satisfied -10 dB impedance bandwidth in UWB frequency band (3.1 ~ 10.6 GHz ). And measured results of gain and radiation patterns characteristics displayed determined for operating bands.

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