• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.278-280
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• 2007

This survey was carried out to provide a sound and a vibration level of bridges on the Han river. A sound and a vibration level of 6 bridges(Ban po, Cheon ho, Olympic, Jam soo, Young dong, Dong ho) were measured. The X-axis vibration level($L_{10}$) was $42{\sim}60$ dB(H), Y-axis vibration level was $41{\sim}52$ dB(H) and Z-axis vibration level was $44{\sim}77$ dB(V). The Z-axis vibration level($L_{10}$) on the midpoint of bridges was 68 dB(V), and on the joint point was 56 dB(V). The sound level was $77{\sim}84$ dB(A). The sound level of Jam soo bridge was higher than any other bridges.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.146-149
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• 2000

SiGe HUT뜰 이용하여 Cellular 주파수 대역(824-849 MHz)에서 MMIC 상향 주파수 혼합기와 가변이득 증폭기를 설계하였다. 동작 전압은 2.7 V 이며, 이중평형 구조의 상향 주파수 혼합기는 12 dB의 변환이득, -0.6 dBm의 1dB 이득압축 출력전력, 30 dB 이상의 LO-RF 단자 격리도 특성, 1.25의 LO-VSWR. 1.34의 RF-VSWR을 가지며, 상호컨덕턴스형 가변이득 증폭기는 35 dB의 최대 선형이득, 13 dBm의 1dB 이득압축 출력전력, 42dB의 가변이득, 23dB의 3차 상호변조 교점 출력전력(OIP$_3$), 1.27의 입력 VSWR, 1.1의 출력 VSWR 특성을 보인다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.890-898
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• 2001

4H-SiC(silicon carbide) MESFET large signal model was studied using modified Materka-Kacprzak large signal MESFET model. 4H-SiC MESFET device simulation have been conducted by Silvaco\`s 2D device simulator, ATLAS. The result is modeled using modified Materka large signal model. simulation and modeling results are -8 V pinch off voltage, under V$\_$GS/=0 V, V$\_$DS/=25 V conditions, I$\_$DSS/=270 mA/mm, G$\_$m/=52.8 ms/mm were obtained. Through the power simulation 2 GHz, at the bias of V$\_$GS/-4 V md V$\_$DS/=25 V, 10 dB Gain, 34 dBm (1dB compression point)output porter, 7.6 W/mm power density, 37% PAE(power added efficiency) were obtained.7.6 W/mm power density, 37% PAE(power added efficiency) were obtained.d.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.224-230
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• 2006

Up to now, there have been rare clinical studies on leaders and aerobics athletes. To get the useful data for protecting from auditory disorder, we selected 15 female aerobics leaders (experimental group) and 15 females (control group) unexperienced in aerobics and a without neurological and octolaryngological disorder. The average age was $34.87{\pm}8.80$ (experimental group) and $34.07{\pm}8.45$ (control group) years, and the average career of an aerobics leader (experimental group) was $8.33{\pm}4.73$ years. We measured the auditory evoked potential (AEP) of the two groups treated with 70, 75 and 85 dB intensity from January 2006 to May 2006 and analyzed the absolute latency (AL) and interpeak latency (IPL) by the SPSS/pc+ 12.0 program. In the comparison of the AL between the experimental group and the control group according to intensity, both ears treated with 70 and 75 dB had a significant difference (p<0.05) in the I, III, V wave and in the I, V wave respectively, and the experimental group treated with 85 dB showed a difference in the I, III, V wave (left ear) and in the I wave (right ear) respectively. The IPL of the two groups treated with various intensities had no prolongation. In the comparison of the AL between the experimental group and the control group according to ages, the experimental group in their 20s treated with 70 dB showed a significant difference (p<0.05) in the V wave (left ear) and in the I, III, V wave (right ear), and the experimental group in their 20s treated with 75 dB in the I, III wave (left ear) and in I, III, V wave (right ear), and experimental group in their 20s treated with 85 dB in the V wave (left ear) and in the III, V wave (right ear). The experimental group in their 30s treated with 70 dB had a significant difference (p<0.05) only in the V wave (right ear). Only in the IPL of subjects in their 20s treated with 85 dB, III-V and I-V of both ears was extended. In the comparison of the AL and IPL according to career, there was no significant difference between the two groups. From this results, we concluded that the lower sound intensity (70 dB) showed a more significant difference in the experimental group than the control group. We concluded that the leader of aerobics exposed to louder sounds than normal people are affected by auditory neurological and octolaryngological disorders. So we think that the leaders of aerobics need to control the noise level for protecting themselves against a disease.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.40-47
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• 2001

The structural dependence of the performance of an 1.55 $1.55{\mu}m$ InGaAsPIInGaAsP MQW electro-absorption modulator for highspeed digital fiber communication was systematically investigated. The effects of n-doped SCH region length $t_n$ as well as the general structure parameters including quantum well number $N_w$, well-thickness $t_w$, detuning wavelength $\Delta\lambda$, and device length L were thoroughly analyzed. Thereby, a high-pelfoIDlance electro-absorption modulator with device length L of $100{\mu}m$ was successfully designed. The designed structure showed excellent characteristics that have residual loss less than -1.5 dB, operational voltage from 0 V to -2V, and extinction ratios of -2.92 dB at $V_{\alpha}$=-1 V and -10 dB at $V_{\alpha}$=-2V.X>=-2V.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.403-409
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• 2013

In this work, a CMOS two stage differential power amplifier which includes Marchand balun, transformer and injection-locked buffer is presented. The power amplifier is targeted for 70 GHz frequency band and fabricated using 65 nm technology. The measurement results show 8.5 dB maximum voltage gain at 71.3 GHz and 7.3 GHz 3 dB bandwidth. The measured maximum output power is 8.2 dBm, input $P_{1dB}$ is -2.8 dBm, output $P_{1dB}$ is 4.6 dBm and maximum power added efficiency is 4.9 %. The power amplifier consumes 102 mW DC power from 1.2 V supply voltage.

• Journal of the Korean Mathematical Society
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• v.59 no.4
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• pp.757-774
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• 2022

Let a and b be positive even integers. An even [a, b]-factor of a graph G is a spanning subgraph H such that for every vertex v ∈ V (G), d_H(v) is even and a ≤ dH(v) ≤ b. Let κ(G) be the minimum size of a vertex set S such that G - S is disconnected or one vertex, and let σ₂(G) = min_uv∉E(G) (d(u)+d(v)). In 2005, Matsuda proved an Ore-type condition for an n-vertex graph satisfying certain properties to guarantee the existence of an even [2, b]-factor. In this paper, we prove that for an even positive integer b with b ≥ 6, if G is an n-vertex graph such that n ≥ b + 5, κ(G) ≥ 4, and σ₂(G) ≥ ${\frac{8n}{b+4}}$, then G contains an even [4, b]-factor; each condition on n, κ(G), and σ₂(G) is sharp.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.45-53
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• 1995

Working depth of the model net was determined by using of the same experimental tank and the same model net that used in the forwarded report in a series studies. The depth of the net which indicates the depth of the head rope from the water surface, was determined by the photographs taken in front of the net mouth with the combination of towing velocity, warp length and distance between paired boats. The results obtained can be summarized as follows: 1. Working depth of model nets A and B was varied in the range of 0.09~1.66$m$,and 0.04~1.34$m$(which can be converted into 2.7~40.2$m$and 1.2~49.8$m$in the full-scale net) respectively, and the depth of model net A was slightly deeper than the depth of the model net B. 2. Working depth ($D$,which is appendixed m for the model net, f for the full-scale net, A and B for the types of the model nets) can be expressed as the function of towing velocity$V_t$, as in the model net($V_t$=$m$/$sec$) $D_{mA}$=(-1.99+0.65$L_w$) $e^{-1.72V_t}$ $D_{mA]$=(-1.91+1.04 $L_w$) $e^{2.88V_t}$ in the full-scale net($V_t$=$k$'$t$ $D_{fA}$=(-29.32+0.65$L_w$)$e^{0.40 V_t}$ $D_{fB}$=(-57.60+1.04$L_w$)$e^{-0.67 V_t}$ 3. Working depth 9$D$ appendixes are as same as the former) can be expressed as the function of warp length$L_w$) in the model net, and can be converted into full-scale net as in the model net ($V_t$=$m$/$sec$) $D_{mA}$=-0.99 $e^{-1.42V_t}$+0.67$e^{-1359V_t}$$L_w$ $D_{mB}$=-.258$e^{-3.77V_t}$+1.16$e^{-3.15V_t$ $L^w$, in the full-scale net($V_t$=k't) $D_{fA}$=-29.28$e^{-0.32V_t}$+0.67$e^{-0.37V_t$$L_w$ $D_{fB}$=-69.10$e^{-0.81V_t}$+1.16$e^{-0.72V_t}$$L_w$. 4. Working depth was gradually shallowed according to the increase of the distance between paired boats.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.416-422
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• 2007

In this paper, a broadband 2-way power divider which can be used from 20 MHz to 500 MHz in the V/UHF band is designed using transmission-line transformer and ferrite toroid. A 2:1 impedance transformer instead of the conventional 4:1 impedance transformer is realized and this 2:1 transformer is connected with the conventional bridge-type 2-way divider to form a 2-way power divider. Insertion loss of about 3.5 dB, isolation of less than -10 dB, and return loss of less than -10 dB in most band of interest are measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.904-912
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• 2007

In this paper, a broadband 4-way power divider which can be used from 20 MHz to 500 MHz in the V/UHF band is designed using transmission-line transformer and ferrite toroid. A 4:1 impedance transformer is realized and this 4:1 transformer is connected with bridge-type 2-way dividers to form a 4-way rower divider, Insertion loss of about 6.8dB, isolation of less than -20dB, and return loss of less than -15dB in most band of interest are measured.