• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.4 no.2
• /
• pp.29-36
• /
• 2005

All-optical fiber-type $2{\times}32$ splitters for an Ethernet PON (passive optical network) were fabricated by using a FBT (fiber biconical tapered) process and the performance of the splitters was tested in upstream transmission of the EPON system. The $2{\times}32$ splitters was obtained by cascading $1{\times}4$ splitters fabricated by a conventional FBT process and showed -18 dB of insertion loss with 1.5 dB uniformity of output power at each channel and -0.1 dB of polarization dependent loss. The insertion loss variation was below 0.1 dB at the temperature range of $-40^{\circ}C\;to\;80^{\circ}C$. For upstream channel transmission test in the EPON system were a Zig board and a burst mode receiver. Zenko-made optical module was used for the burst mode receiver by adding functions of serializer/deserializer and clock data recovery, a Virtex II pro20 chipset and Vitesse VSC7123 were used in the Zig board for characterizing the burst mode and in the clock data recovery chipset, respectively. Startup acquisition lock time and data acquisition lock time were measured to be 670ns and 400ns, respectively, in the upstream channel transmission of the EPON system adapting the $2{\times}32$ splitter fabricated in this work.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.42 no.4
• /
• pp.69-76
• /
• 2005

In this paper, a 2 stage 6-pole bandpass filter(BPF) is designed and implemented by using triple-mode cavity for satellite payload system. The BPF has a 100MHz bandwidth at the center frequency of 14.5GHz(Ku-band) and the response of the filter is the Chebyshev function. The cavity filter uses two orthogonal $TM_{113}$ modes and one $TM_{012}$ mode. The coupling between the adjacent cavityes(intercavity coupling) results in a Chebyshev response and is accomplished by only H-filed component of If modes. The size and location of intercavity slot is determined by the coupling equation from E-and H-field of TE and TM resonant modes in circular cavity. The 2-stage 6-pole triple-mode cavity BPF has the insertion loss of 2.4dB and the reflection loss of 15dB in the passband. The triple-mode BPF proposed in this thesis can be used as channel filters for satellite payload system and can minimize filter assembly in general wireless communication system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.6
• /
• pp.914-919
• /
• 2000

A simple orthogonal mode transducer(OMT) for X-band has been proposed in this paper. This OMT is designed such that a polarized wave can be guided in a direction using several thin guiding posts, and the other orthogonally polarized wave can be guided in the other direction using other thin guiding posts. The OMT consists of a T-shaped waveguide section with guiding posts, two tapering waveguide arms, and has three flanges for connection with two adapters and an antenna. The optimum numbers and the optimum positions of the guiding posts were obtained numerically using the HFSS CAD tool. The isolation between two polarizations in a manufactured OMT is higher than 42.8 dB and the reflection from the OMT is lower than -17.5 dB at the frequency band of 9.5 GHz

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.1
• /
• pp.1-11
• /
• 2009

Statement of problem: There are two methods of color choice for the esthetic restoration. One is visual shade matching which draws a comparison between shade guide and teeth in dentist's own eye and the other is using a digital shade analysis system recently introduced. Although the visual shade matching has a lot of problems, decision of color by this visual shade matching and the ways of expression for the decided color are still applicable to clinical dentistry. Purpose: This study is designed to investigate shade guides used in the dental clinics and laboratories have the same value using ShadeEye-$NCC^{(R)}$ dental chroma meter (Shofu Inc., Kyoto, Japan) using shade guide are evaluated. Material and methods: At the first experiment, eight Vita Lumin Vacuum shade guides (Vident Inc., California, USA) were collected from the dental clinics. A1 and B1 shade tabs are chosen and the colors are analyzed five times each in both tooth and porcelain modes by digital shade analysis system, ShadeEye-$NCC^{(R)}$. In the second experiment, twelve Vita shade guides using practically in the dental clinics and laboratories were collected and also A1 and B1 shade tabs are chosen and the colors of A1 and B1 are analyzed one time each in both tooth and porcelain modes by ShadeEye-$NCC^{(R)}$. Results and conclusion: There were significant differences among eight shade guides in terms of shade (chroma), value and hue in both of A1 and B1 (P<.05). Shade guides using in present both dental clinics and laboratories did not show significant differences, except A1 in the porcelain mode, it showed significant differences (P<.05) in the shade even though the shade tab has the same name.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2001.10a
• /
• pp.262.1-262
• /
• 2001

• Journal of IKEEE
• /
• v.9 no.2 s.17
• /
• pp.115-122
• /
• 2005

We report 400 femto-second highly stable, nearly transform-limited, pulse generation at 10 GHz in $1540{\sim}1550$ nm wavelength region by adiabatic soliton pulse compression of an actively mode-locked fiber ring laser output. Without using any supermode selection device, supermode beating noise has been suppressed below -123 dB/Hz, resulting less than 100 femto-second timing jitters at the noise band of $1\;kHz{\sim}100\;MHz$.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.6
• /
• pp.314-324
• /
• 2006

In recent years, having the advantages of being small, low in cost and high in efficiency, Half-wave resonant type, (having only one output diode), is used in ZVS Half-Bridge DC/DC converter. This paper presents the operation mode by multi-resonant factors in the Half-wave type multi-resonant converter with direct Buck chopper circuit operated in discontinuous current mode. To study the characteristics of a multi-resonant operation in steady-state, the characteristic impedances in each mode and safe operation-region(S.O.R) are reported. Computer simulation and experimental data are also riven to verify the theoretical results.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.3
• /
• pp.56-61
• /
• 1996

In this paper, new buck converter of a TV power system is presented. First, we devised a revised driving circuit for an emitter-coupled type buck converter, by which it is possible to reduce the material cost of transformers and voltage stress of power device. Secondly, we adopted a hybrid oscillation technique. When TV system is in off-stage, initial standby power which is necessary for remote controllable TV system is supplied by self-oscillating mode. Main power which is necessry in TV system bing on state is provided by an externally triggered oscillating mode. The switching frequency is synchronized to the oscillating frequency of horizontal deflection in TV, by which we can reduce picture noises and the size of power transformer. Thirdly, a simple error amplifier is inserted to the feed-back loop to keep the output voltage constant which means pulse width modulatio mode is added in driving part of power device. Finally, we showed by experiments that our proposed converter performs well enough to be close to the theoretically predicted values.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.8
• /
• pp.1031-1039
• /
• 1999

Electrospraying comprises the generation of liquid droplets by applying a high voltage to the surface of a liquid. By monitoring the current and the flow rate it was possible to obtain a stable cone jet mode in a given condition. In this work the liquid contained NaCl particles resolved in distilled water. The NaCl particles increased concentration of the ionized solution and thus increased electrical conductivity of the liquid, which was inversely proportional to the flow rate in the cone jet mode. A number of sprayed droplets were sampled and dried enough, and then the size of NaCl particles were measured. The measured droplet diameter was a little larger than two theoretical diameters, Rayleigh diameter and mobility diameter.

• Journal of Advanced Navigation Technology
• /
• v.14 no.1
• /
• pp.102-107
• /
• 2010

This paper presented a rate-distortion estimation method for effective mode decision in H.264/AVC. In this approach, in order to decide a mode, laplacian distribution modeling of DCT coefficients is utilized, which do not need to such process as quantization, entropy coding. From the simulation results, proposed a method showed that rate-distortion between proposed scheme and practical value was almost the same and performed 0.02dB of PSNR gain.