• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.195-203
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• 2017

A 2U cube satellite called SNUGLITE has been developed by GNSS Research Laboratory in Seoul National University. Its main mission is to perform actual operation by mounting dual-frequency global positioning system (GPS) receivers. Its scientific mission aims to observe space environments and collect data. It is essential for a cube satellite to control an Earth-oriented attitude for reliable and successful data transmission and reception. To this end, an attitude estimation and control algorithm, Attitude Determination and Control System (ADCS), has been implemented in the on-board computer (OBC) processor in real time. In this paper, the Extended Kalman Filter (EKF) was employed as the attitude estimation algorithm. For the attitude control technique, the Linear Quadratic Gaussian (LQG) was utilized. The algorithm was verified through the processor in the loop simulation (PILS) procedure. To validate the ADCS algorithm in the ground, the experimental verification via a single axis Hardware-in-the-loop simulation (HILS) was used due to the simplicity and cost effectiveness, rather than using the 3-axis HILS verification (Schwartz et al. 2003) with complex air-bearing mechanism design and high cost.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.2
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• pp.131-134
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• 2003

Epithelial-myoepithelial carcinoma(EMC) of the salivary glands is a rare tumor first discribed in 1972. The EMC comprises approximately 1% of all salivary gland tumors. It is characterized by tubular and solid growth pattern with a dual cell population including an inner layer of epithelial cells, which is peripherally bounded by a layer of clear myoepithelial cells. It is demonstrated that tumor with solid slowly growing pattern, generally have a higher frequency of local recurrence. We report a case of parotidic EMC in a 30 years old woman with literature review

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.159-167
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• 2018

In this paper, we propose an algorithm to optimize energy efficiency in a multi-user decoupled RF energy harvesting network and experiment on the trend of energy efficiency change assuming users' various geographical distribution scenarios. In the RF energy harvesting network where both wireless data transmission and RF energy harvesting are simultaneously performed, the energy efficiency is a key indicator of network performance, and it is necessary to investigate how various factors can affect the energy efficiency. In order to increase energy efficiency effectively, we can confirm that users' distributions are important factors in the RF energy harvesting network from the simulation results.

• Journal of the Korean Dietetic Association
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• v.7 no.4
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• pp.361-372
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• 2001

This study was conducted to investigate the status of calcium intake and serum calcium level in perimenopausal women. The age distribution of the subjects was 49-55 years. Daily nutrient intake and dietary sources of calcium were analyzed by a convenient method and a food frequency questionnaire. At the same time, fasting blood samples were collected and serum calcium concentration was measured. The BMD of subjects was measured by Dual Energy X-ray Absorptiometry (DEXA). Fifty percent of the subjects under 50 years of age ($\leq$49 yr group) and 66.9% of the subjects from 50 years and up ($\geq$50 yr group) were classified as osteopenia or osteoporosis. Intake of energy (p<0.001), protein (p<0.05), fat (p<0.05), calcium (p<0.01) was significantly different between $\leq$49 yr group and $\geq$50 yr group. Mean daily intake of calcium was much lower than the Korean RDA : 94.9% in $\leq$49 yr group and 87.4% in $\geq$50 yr group. The average concentration of total calcium in serum was within the normal range in $\leq$49 yr group. Serum calcium concentrations were significantly (p<0.05) different between $\leq$49 yr group and $\geq$50 yr group. It was noteworthy that serum calcium concentration was positively related to the intake of protein, fat and calcium. Lettuce, sea mustard, bean-curd, anchovy, radish and perilla leaf was included among the major sources of dietary calcium. Further investigation is necessary to make sure of the relations between BMD and serum calcium level and calcium intake.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.393-400
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• 2014

In this paper, we have designed the transmitter for earth station terminal operating with military geostationary satellite on Ka-band that is complied with MIL-STD-188-164A. The designed antenna of this terminal is dual-offset gregorian reflector which is consist of corrugated horn and iris polarizer, othermode transducer. This antenna meets radiation pattern and transmit EIRP spectral density requirements in this standard. The designed RF systems of this terminal are consist of Block Up Converter(BUC) converting frequency band from IF to Ka band and SSPA having low-power consumption and compact light-weight using the pHEMT MMIC compound devices. This RF systems applied with VSWR, spurious/harmonic suppression, output flatness and phase noise requirement in this standard.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.1
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• pp.58-65
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• 2013

It's introduced a BLA(Branch Loop Antenna) that is modified from conventional loop, and verified antenna performances for applying to mobile handset. Branch elements are added to a rectangular loop, and low resonance is obtained by the length of the branch line. When resonance frequency of a single loop is 2.5GHz, BLA had near 900 MHz under the same antenna size. Multiple resonances are established by the locations of branch connection and their lengths. By the implementation and measurement for the dual band BLA, it's showed 75MHz -10dB bandwidth and -3.03~-1.46dBi average gains with 49.73~71.39% efficiencies at GSM900 band, and 90MHz -6dB bandwidth and -8.14~-2.17dBi average gains with 15.34~60.62% efficiencies at DCS1900 band. And H-plane radiation patterns were omni-directional. These performances are good for the mobile handset antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.451-460
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• 2004

The pilot bit pattern of W-CDMA system is used for the channel estimation and frame synchronization confirmation. This paper proposes the binary sequences for the frame synchronization for wideband code division multiple access (W-CDMA) system. We present the circuit for the generation of ideal frame synchronization property using the binary sequences called frame synchronization word(FSW). W-CDMA system uses compressed mode where up to 7 slots per one 10 msec frame are not transmitted to make measurements from another frequency without a full dual receiver terminal. It is shown that the proposed frame synchronization words also maintain the optimal frame synchronization property in the compressed mode by using the complementary mapping relationship of preferred pair. And we discuss the realization circuit for the generation of frame synchronization words by using the concept of preferred pairs, complementary mapping relationship, and maximal length sequence.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1150-1156
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• 2007

In this paper, two novel subsurface antennas for remote management of underground facilities using PCS and cellular wireless network are proposed. The proposed subsurface antenna is a dual band circular patch which is inserted and molded for the protection of the antenna into a metal such as a manhole cover. The antenna is designed considering the resonant frequency shift of the antenna due to the insertion and molding. The measured return loss and receiving power of the fabricated antenna comparison with a dipole shows that two proposed subsurface antenna can be used for remote management of underground facilities using PCS and cellular systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1259-1268
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• 2010

In this paper, we presented a new LC prototype synthesis method for the multi-band filter. For synthesis a multi-band filter with the required frequency response, we proposed the diagram of poles and zeros, also, we proposed the optimization process for finding the combination of optimized poles and zeros. From the transfer and reflection functions calculated from poles and zeros, we performed the quasi-elliptic LC prototype synthesis of multi-band filter. Using the proposed LC prototype synthesis method of multi-band filter, dual-band filter operating at GSM(880~960 MHz) and ISM(2,400~2,500 MHz) and triple-band filter operating at GSM(880~960 MHz) and ISM(2,400~2,500, 5,725~5,850 MHz) were designed and fabricated.

• Journal of Family Resource Management and Policy Review
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• v.15 no.2
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• pp.103-128
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• 2011

The purpose of this study is to analyze the family sharing time of housework and to examine the sharing time with family is influenced by socio-demographic variables. The Time Use Survey data collected by Korean National Statistical Office in 2009 is used. Among the total sample of 21,000 individuals, 9,179 samples who are married, aged from 20 to 59 years old and non-farmers are selected for analysis. The statistical methods are frequency, percentage, crosstabulation, t-test, and regression analysis. The following is a summary of the major findings. First, comparison of men and women shows women spend more time on housework than men do. But sharing housework time with family for men increase on Sunday. Performer average is almost same in men and women. Secondly, the family sharing time on housework is longer on Sunday. It is due to increase of men's family sharing time. It means that men's time substitute for women's housework. Thirdly, the influencing factors on family sharing housework are gender, age, education, presence of spouses, monthly income, dual earner status, weekly working hours, gender role atittude and presence of preschoolers. Family sharing housework is not only household labor but also family pleasure time. It means family policy should focus on making family time for workers fundamentally. And family policy needs to make a system of educational program for work-family balance.