• Journal of Korean Electronics
• /
• v.6 no.6
• /
• pp.36-38
• /
• 1986

• TTA Journal
• /
• s.38
• /
• pp.47-61
• /
• 1995

• KOREAN POULTRY JOURNAL
• /
• v.20 no.8 s.226
• /
• pp.42-43
• /
• 1988

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.2
• /
• pp.31-40
• /
• 1999

Characteristics of monopole antenna and planar conductor structure mounted on handheld telephone are anlayzed by using FDTD method. Feeding of monopole antenna is implemented with lumped elements and plastic case is coated on the surface of conductor box. Otherwise, resonant frequency of handheld telephone mounting monopole antenna with no plastic case is 877MHz, when plastic case (${\varepsilon}_r=2$) is coated, the resonant frequency is down to 82MHz and the bandwidth is broadened about 1.5 times. Planar structure of handheld telephone mounted on the body makes to change far-field gain radiation patterns. In this case, radiation patterns are somewhat asymmetrical. Handheld telephone using PIFA(Planar Inverted F Antenna), instead of monopole antenna, is resonated at frequency 1.52GHz that is available onPCS. In the radiation pattern of this structure, azimuth that electric field intensity is presented below 20dB is 14$^{\circ}$.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.5
• /
• pp.857-864
• /
• 2020

The multi-functional VoIP phone supports the Ethernet protocol in the TIPS(: Tactical IP Switch), which is one of the sub-systems of the tactical information and communication system (TICN). It provides secured voice / video calls in conjunction with VoIP exchanges and supports differential services such as multi-party calls and command functions. In this paper, improving methods have been proposed to reduce power supply defects in the field of multi-functional VoIP phones. The power supply part was improved by applying TVS of the output voltage inlet of the dedicated adapter of the multi-functional VoIP phone, TVS of the PoE module input, adding blocking diodes, and adding DC / DC converters behind the poly-switch. Also, functional and environmental tests were performed to verify the validity of the proposed methods.

• The KIPS Transactions:PartB
• /
• v.9B no.6
• /
• pp.799-808
• /
• 2002

With the enormous advance of communication technology, telephone numbers to be memorized is increased because most people have a lot of telephone numbers. Thus it needs a method for people to easily memorize those telephone numbers. A traditional method is to use Korean nickname by 4 syllable Korean words such as "Pal -li Pal-li," "Yi- sa Yi-sa" whose initial sounds are corresponding to Korean sounds of telephone numbers. However, this method does not apply to all the telephone numbers, and only apply to a few telephone numbers. This paper proposed a Hangul-phone keyboard (TELNICK) considering the reduction of finger's moving distance and the number of strokes, and the generation of Korean nicknames for easy memorizing. This paper also proposes a method to generate many Korean nicknames that can correspond to 4-digit or 3-digit telephone numbers by using TELNICK keyboard and presents the form of Korean nicknames that can correspond to 7-digit or 8-digit telephone numbers.t telephone numbers.

• Archives of design research
• /
• v.11 no.3
• /
• pp.35-44
• /
• 1998

Acording to the trend of highly increasing the public telephone, understanding consumer's design sensibility is based on designing consumer products reflecting user's identity and it comes out as a result of wore competitive products. For this study, consumer's desirous sensibility of the public telephone has been measured in checkable numbers. First of all, 35 sensible words are narrowed down from 168 whole sensible(adjective) words using the SD method. By this result, 7 scale form the SD method is applied to reserch on 10 current distributed products form 30 male and female university students. Element factor analysis is used to group the selected sensible words, duster analysis is used yo dassify them, and finally discriminant analysis is used to predict the relationship between design elements and the sensible words. As a result, words of human sensibility is known to divide into 3 factors; esthetics, functionality and safety, and the correlation of design factor is closely related with the the telephone's body, handset, dial board, dial button, ontrol button, color and material. To sum up, better public telephone design comes out from scientific and systematic consumer's desire analysis not designer's design technique.

• 전자공학회논문지 IE
• /
• v.44 no.4
• /
• pp.1-10
• /
• 2007

In this thesis, we study the implementation of hands-free phone in a car, taking acoustic echo canceller, in order to remove acoustic echo effectively. Conventional coustic echo canceller used for only adaptive filtering has much difficulty to solve both echo and double-talk problem. To tackle this problem, we propose acoustic echo canceller consisting of adaptive filter using a modified NLMS, VAD to catch exact voice activity duration using two independent forgetting factors, double-talk detector to detect fast and precise double talk duration using cross-correlation between microphone signal and residual echo, and output controller using VAD and double-talk detector. The proposed hands-free phone taking acoustic echo canceller shows the performance that has not acoustic echo and guarantees full duplex.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.6A
• /
• pp.445-454
• /
• 2005

To measure the performance of call quality, we have built the experiment environment and observed that the delay caused by encapsulation between internet and VoIP telephones is under 5ms at most. The major delay is assumed to be the time required to capsulate the packet for tunnelling of VPN. Because the difference of average delay time is under $4ms{\sim}5ms$, the difference of call quality between VoIP and VoIP telephone adopting VPN is negligible. We have concluded that the capsulation process between PAC and PNS is the major factor influencing the network load by changing the number of fames in a packet during communication Also, we have concluded that the most suitable frame numbers is tow or three by adding the frame numbers in a packet to obtain the suitable frames in a packet and setting up end-to-end delay under 150ms.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.6 no.3
• /
• pp.3-14
• /
• 1995

The broadband input impedance, the input power and the radiation pattern of the monopole antenna attached to the handy phone operated at 800MHz are calculated by using the Finite Difference Time Domain(FDTD) Method. For the FDTD analysis of frequency characteristics of monopole antenna, the handy phone is modeled with the geometry that the monopole antenna is connected to a conducting box, and the modified FDTD algorithm[11] used the thin wire appproximation method and the Maxwell's integral equation from the original Yee algorithm is applied for the analysis of the wire structure. Also, by means of finding the current distribution directly from circumferencial magnetic filelds around the monopole antenna and the conducting box, the radiation pattern is calculated to observe the influence of the conducting box, and is compared with the results of the known mothod for the FDTD calculation of radiation pattern, For the experiments, the handy phone of which full length including antenna is .lambda. $\lambda$/2 is manufactured and we confirm that all computation results are agree well with the mea- sured values.