• Journal of the Microelectronics and Packaging Society
• /
• v.29 no.3
• /
• pp.55-61
• /
• 2022

In this study, properties of Pb-free solder joints which were combined using Sn-3.0Ag-0.5Cu (SAC305) Pb-free solder with a mid-temperature type of melting temperature and Sn-57Bi-1Ag Pb-free solder with a low-temperature type of melting temperature were reported. Combined Pb-free solder joints were formed by reflow soldering processes with ball grid array (BGA) packages which have SAC305 solder balls and flame retardant-4 (FR-4) printed circuit boards (PCBs) which printed Sn-57Bi-1Ag solder paste. The reflow soldering processes were performed with two types of temperature profiles and interfacial properties of combined Pb-free solder joints such as interfacial reactions, formations of intermetallic compounds (IMCs), diffusion mechanisms of Bi, and so on were analyzed with the reflow process conditions. In order to compare reliability characteristics of combined Pb-free solder joints, we also conducted thermal shock test and analyzed changes of mechanical properties for joints from a shear test during the thermal shock test.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.6
• /
• pp.1032-1037
• /
• 2016

In this paper, the method of isolation enhancement for the mobile phone MIMO antenna of LTE class 40(2300~2400MHz) was studied. Design of MIMO antenna was based on the hybrid antenna that operates both a monopole and an IFA(Inverted F Antenna). A structure for the isolation enhancement which controls induced electric field on the ground plane is located between MIMO antenna, and was not connected with the ground but apart 0.3mm. A MIMO antenna that operates on class 3~40(1710~2400MHz) of LTE service bands and a structure for the isolation enhancement at the class 10 band were designed. VSWR measurement of implemented antenna on the FR4 board showed within 3:1 at entire design bands, and isolation between antennas at the class 40 band was less than -30dB. Isolation was enhanced more than 20dB by the studied structure. ECC(Envelope Correlation Coefficient) for MIMO performance was under 0.1, and antenna average gain and efficiency measured in the anechoic chamber were -4.28~-1.40dBi and 37.32~72.36% respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2010.04a
• /
• pp.151-153
• /
• 2010

In this paper, the tri-band planar monopole microstrip antenna which stimulaneously meets the three bands such as TRS, WLAN and DMB is designed. The designed antenna size was smaller using CPW-fed structure that shows a ground-plane and a patch-plane are existed at one layer. The proposed antenna is designed on FR-4 substrate with a relative dielectric constant 4.3, thickness of 1.5mm and tangent loss 0.04. The designed antenna shows that VSWR is below 2 and has good return loss below -10dB over the three bandwidths.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.7 no.3
• /
• pp.142-146
• /
• 2014

In this paper, an antenna which has quad band in GSM/DCS/PCS/Bluetooth is proposed. This structure is designed with miniaturization for wide band characteristic based on monopole antenna and log-periodic toothed trapezoid patch antenna which has slots. To achieve multi-bandwidth is used the microstrip line on the substrate. An antenna size is $35mm{\times}20mm$ on FR-4(${\varepsilon}r=4.4$) ground substrate of $35mm{\times}75mm{\times}1mm$ size. And proposed antenna is satisfied with impedance bandwidth(VSWR ${\leq}$ 3). The simulated maximum radiation gain is 1.92 dBi, 3.26 dBi, 3.97 dBi at the center frequency of 0.92 GHz, 1.97 GHz, 2.45 GHz, respectively.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11a
• /
• pp.130-133
• /
• 2010

본 논문에서는 X-band 절전센서용 마이크로스트립 구형패치 배열 안테나의 설계 방법을 제안 하고자 한다. 제안된 배열 안테나는 송 수신 안테나가 각각 1x2배열로 구성 되었다. 안테나는 CST MWS를 사용하여 시뮬레이션 하였고 FR-4 기판(h=1.0mm, ${\varepsilon}_r$=4.4)을 사용하여 제작하였다. 시뮬레이션 결과는 대역폭이 4%(VSWR${\leq}$2), 이득은 6.3dBi, 빔폭은 약 $60^{\circ}$(El)/$15^{\circ}$(Az)로 예측되었다. 안테나는 시뮬레이션 결과를 바탕으로 제작 되었고 절전센서용 RF 송수신기 회로 뒷면에 설치되어 무반사실에서 방사 특성을 측정하였다. 측정된 결과는 대역폭이 7%(VSWR${\leq}$2), 이득은 4.8dBi, 빔폭은 약 $55^{\circ}$(El)/$15^{\circ}$(Az)로 시뮬레이션 결과와 매우 유사한 결과를 얻었다.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.8 no.2
• /
• pp.201-205
• /
• 2004

During the routine survey, the mortality of mulberry seedlings was noticed due to damping-off disease. The disease recognized by rotting of emerged seedlings near the soil line (just below the soil level) resulting in collapse of the seedlings. Two fungi were isolated from affected samples and identified as Alternaria alternata (Fr.) Keissler and Fusarium solani (Mart.) Sacc. Both the fungi were found to be responsible in causing pre and post emergence damping-off of seedlings in mulberry. For management of the disease, an experiment was conducted using fungicides. These fungicides were applied as seed treatment; soil drenching and foliar spray alone and in combination. Among the different treatments, integration of seed treatment and soil application of Dithane M-45 (Mancozeb 75% WP) + Bavistin (Carbendazim 50% WP) followed by foliar spray of these fungicides (after 35 days of sowing) resulted in better survivability of seedlings (93.3 %) on $90^th$ day and controlled the pre and post emergence damping off by 100 and 89.5%, respectively over the check.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.9 no.2
• /
• pp.11-15
• /
• 2013

We in order to use WLAN communication device planned wireless USB dongle internal antenna of 2.4 GHz/5.8 GHz band. So it uses square patch dual-wideband and quality is satisfactory and it designed print folded monopole antenna of the shape which is simple. The thickness of the antenna was fed by a $50{\Omega}$ coaxial cable feeding 1mm dielectric constant 4.4 FR4 substrate was used. The overall size of the antenna is $20mm{\times}50mm$. So the internal antenna is suitable. Measurement results of the fabricated antenna, the return loss of more than 10 dB in the two bands could be obtained. Radiation pattern has a maximum gain of 3.75 dBi value.

• Journal of IKEEE
• /
• v.28 no.3
• /
• pp.303-309
• /
• 2024

This paper proposes a high-gain phased array antenna that can provide private network communication services for large office spaces, factories, and other large-scale facilities, specifically designed for millimeter-wave band 5G (5th generation) networks. The proposed antenna features a 4×4 array structure with eight sub-arrays, each consisting of a 1×2 series array. To achieve high side-lobe characteristics, an offset array structure is applied by shifting even-numbered rows by one unit, combined with power tapering to adjust the size of individual radiating elements. This design achieves a high side-lobe level (SLL) of 22.3 dB and a high gain of 18.1 dBi. Additionally, the antenna provides gain characteristics of at least 15.2 dBi and 17.4 dBi within the intended beam steering range of ±45° in the azimuth direction and ±10° in the elevation direction, ensuring smooth communication services over a wide service area.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.47 no.11
• /
• pp.91-96
• /
• 2010

In this paper, an internal USB dongle antenna with a circular hook-shaped patch is proposed. The proposed antenna comprises of a circular hook-shaped patch and a monopole stub. The proposed antenna with the dimension of $10mm{\times}50mm{\times}0.8mm$ was fabricated on commercial FR-4 substrate with a dielectric constant of 4.6 and tangent loss of 0.025. The designed antenna exhibits three different resonant bandwidths, 2.4 GHz-2.5 GHz, 3.4 GHz-3.6 GHz, and 5.15 GHz-5.825 GHz. The measured radiation patterns are omni-directional at measured frequencies. Therefore, the proposed antenna is suitable for wireless USB dongle antenna that can support multiband wireless services such as WLAN, WiMAX and Bluetooth.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.6
• /
• pp.1015-1022
• /
• 2023

In this paper, we propose DLP(Dual Linear Polarization) antenna with aperture coupled feeding structure for private network. The proposed antenna has general aperture coupled structure and design two port between top and bottom layer to obtain the enhanced isolation. Also, The size of each substrate(top and bottom layer) is 34.0 mm(W)×34.0 mm(L), which is designed on the FR-4 substrate which thickness (h) is 1.0 mm, and the dielectric constant is 4.4. Also, the size of patch antenna is 12.70 mm(W2)×14.60 mm(L3), and it is located on the top layer. The size of feeding line is 24.0 mm(W2)×1.6 mm(L3), and is located at the bottom layer Also, rectangular slot is located on the ground plane between top layer and bottom layer. From the fabrication and measurement results, bandwidths of 300 MHz (4.52 to 4.82 GHz) for feeding port 1, and 170 MHz (4.65 to 4.82 GHz) for feeding port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is got under the -30 dB. Also, cross polarization isolation between each feeding port obtained