• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.5
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• pp.43-51
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• 2010

Attenuation coefficients of medical ultrasound not only reflect the pathological information of tissues scanned but also provide the quantitative information to compensate the decay of backscattered signals for other medical ultrasound parameters. Based on the frequency-selective attenuation property of human tissues, attenuation estimation methods in spectral domain have difficulties for real-time implementation due to the complexicity while estimation methods in time domain do not achieve the compensation for the diffraction effect effectively. In this paper, we propose the modified VSA method, which compensates the diffraction with reference phantom in time domain, using adaptive bandpass filters with decreasing center frequencies along depths. The adaptive bandpass filtering technique minimizes the distortion of relative echogenicity of wideband transmit pulses and maximizes the signal-to-noise ratio due to the random scattering, especially at deeper depths. Since the filtering center frequencies change according to the accumulated attenuation, the proposed algorithm improves estimation accuracy and precision comparing to the fixed filtering method. Computer simulation and experimental results using tissue-mimicking phantoms demonstrate that the distortion of relative echogenicity is decreased at deeper depths, and the accuracy of attenuation estimation is improved by 5.1% and the standard deviation is decreased by 46.9% for the entire scan depth.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.327-336
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• 2020

The purpose of this study was to examine the characteristics of the high caries risk group of 12-year-old children in Korea. Oral health status and interview data were collected from 23,089 children aged 12 years who participated in the 2015 Korean Children's Oral Health Survey. Subjects were classified into high-risk and low-risk groups according to the Significant caries (SiC) index, and the influence of each variable was analyzed. As a result of the study, the SiC index of the high-risk group was 5.08, which was about 9.6 times higher than the low-risk group. The risk factors associated with the high-risk group were in the order of the number of sealant teeth, dental treatment demand for the past year, perceived oral health status, gender, region, frequency of snack intake per day, and use of oral hygiene aids. In order to improve the oral health of children, appropriate preventive treatment and oral health education should be carried out with reference to the items indicated as risk factors in the high-risk group of dental caries.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.366-373
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• 2013

This paper discusses the singly curved phased reflector for reduced RCS pattern, which has minimized RCS level at boresight with a null by phase cancelation and the lowered RCS level of main beam by splitting the main beam into multi directions. Considering the reduced level of boresight and main beam compared to the same sized reference PEC, this proposed multi-beam reflector can be adopted in the mono-static radar and the bi-static radar environment. The proposed reflector is a multi-beam reflector, which has different phase distributions at each row for different steering angle. It is designed through an intermediate stage of a single and dual-beam reflector. The behaviors of the designed reflectors are verified through full-wave simulation and experiment. The reflectors are designed in the frequency of 10 GHz and it has a size $240{\times}180mm^2$($8{\times}6\;{\lambda}^2$) with the curvature k=3.3. From the measured results, the proposed reflectors reduce the reflected power by 17 dB at boresight.

• Journal of Gastric Cancer
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• v.1 no.3
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• pp.155-160
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• 2001

Purpose: Submucosal gastric carcinomas metastasize to lymph nodes more often than the intramucosal gastric carcinomas. The objectives of this study are to clarify the characteristics of submucosal gastric carcinomas, especially in reference to the status of lymph node metastasis, and to explore the possibility of a minimally invasive operation. Materials and Methods: The clinicopathologic features of 88 patients with submucosal gastric carcinoma, all of whom were treated with a $D_{2}+\alpha$ gastrectomy between January 1994 and December 1999, were examined retrospectively with respect to the status of lymph nodes. The size, depth of submucosal invasion, histologic differentiation, location,and macroscopic finding of the tumor were investigated in association with the presence or the absence of lymph node metastasis. Results: Among the 88 patients, 15 ($17.05\%$) had lymph node metastasis, and the status of metastasis was significantly correlated with tumor size and depth of submucosal invasion. The frequency of metastasis was $0\%$ (0/7) of up to 1.0 cm and $18.5\%$ (15/81) over 1.0 cm in size (p=0.034) and $6.1\%$ (2/33) of up to 1.0mm and $23.6\%$ (13/55) over 1.0 mm in depth of submucosal invasion (p=0.042). Conclusion: The tumor size and depth of submucosal invasion are useful indicators of lymph node metastasis in submucosal gastric carcinoma. A minimally invasive operation can be applied for submucosal gastric carcinoma up to 1.0 cm in size Further studies are needed to limited surgery for depth of submucosal invasion.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.10-20
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• 2007

For spacecraft attitude control, reaction wheel (RW) steering laws with more than three wheels for three-axis attitude control can be derived by using a control allocation (CA) approach.1-2 The CA technique deals with a problem of distributing a given control demand to available sets of actuators.3-4 There are many references for CA with applications to aerospace systems. For spacecraft, the control torque command for three body-fixed reference frames can be constructed by a combination of multiple wheels, usually four-wheel pyramid sets. Multi-wheel configurations can be exploited to satisfy a body-axis control torque requirement while satisfying objectives such as minimum control energy.1-2 In general, the reaction wheel steering laws determine required torque command for each wheel in the form of matrix pseudo-inverse. In general, the attitude control command is generated in the form of a feedback control. The spacecraft body angular rate measured by gyros is used to estimate angular displacement also.⁵ Combination of the body angular rate and attitude parameters such as quaternion and MRPs(Modified Rodrigues Parameters) is typically used in synthesizing the control command which should be produced by RWs.¹ The attitude sensor signals are usually corrupted by noise; gyros tend to contain errors such as drift and random noise. The attitude determination system can estimate such errors, and provide best true signals for feedback control.⁶ Even if the attitude determination system, for instance, sophisticated algorithm such as the EKF(Extended Kalman Filter) algorithm⁶, can eliminate the errors efficiently, it is quite probable that the control command still contains noise sources. The noise and/or other high frequency components in the control command would cause the wheel speed to change in an undesirable manner. The closed-loop system, governed by the feedback control law, is also directly affected by the noise due to imperfect sensor characteristics. The noise components in the sensor signal should be mitigated so that the control command is isolated from the noise effect. This can be done by adding a filter to the sensor output or preventing rapid change in the control command. Dynamic control allocation(DCA), recently studied by Härkegård, is to distribute the control command in the sense of dynamics⁴: the allocation is made over a certain time interval, not a fixed time instant. The dynamic behavior of the control command is taken into account in the course of distributing the control command. Not only the control command requirement, but also variation of the control command over a sampling interval is included in the performance criterion to be optimized. The result is a control command in the form of a finite difference equation over the given time interval.⁴ It results in a filter dynamics by taking the previous control command into account for the synthesis of current control command. Stability of the proposed dynamic control allocation (CA) approach was proved to ensure the control command is bounded at the steady-state. In this study, we extended the results presented in Ref. 4 by adding a two-step dynamic CA term in deriving the control allocation law. Also, the strict equality constraint, between the virtual and actual control inputs, is relaxed in order to construct control command with a smooth profile. The proposed DCA technique is applied to a spacecraft attitude control problem. The sensor noise and/or irregular signals, which are existent in most of spacecraft attitude sensors, can be handled effectively by the proposed approach.

• Journal of Life Science
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• v.18 no.9
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• pp.1225-1229
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• 2008

A total of 10 polymorphic microsatellite markers on bovine chromosome 5 were used for allelic association tests with phenotypic characteristics in Hanwoo. The data analyzed in this study were collected from 326 steers. Chi-square tests were performed to compare the frequencies of individual alleles between the high and the low breeding value groups. The following breeding values were analyzed for QTL effects. The frequency of allele 239 of DIK2828 showed a significant difference between the high and the low breeding value groups in the breeding value of marbling score (MSBV). The allele 279 of BMC1009 was found to show significant differences in allelic distribution for the breeding value of cold carcass weight (CWBV) and the breeding value of backfat thickness (BFBV) and allele 285 showed significant differences in allelic distribution for CWBV, BFBV, and MSBV. The allele 200 of DIK4329 showed significant differences in allelic distributions for the breeding values of longissimus muscle area (LMABV) and BFBV. In this study, we identified the QTL for carcass traits at around 20 (DIK2828), 41 (BMC1009) and 95 (DIK4329) cM in chromosome 5. The results provided a useful reference for further positional candidate gene research and marker-assisted selection for fat metabolism and carcass traits.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.62-71
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• 2013

The passive emitter location method using TDOA and FDOA measurements has higher accuracy comparing to the single TDOA or FDOA based method. Moreover, it is able to estimate the velocity vector of a moving platform. Recently, several non-iterative methods were suggested using the nuisance parameter but the common reference sensor is needed for each pair of sensors. They show also relatively low performance in the case of a long range between the sensor groups and the emitter. To solve this, we derive the estimation method of the position and velocity of a moving platform based on the Gauss-Newton method. In addition, to analyze the estimation performance of the position and velocity, respectively, we decompose the CRLB matrix into each subspace. Simulation results show the estimation performance of the derived method and the CEP planes according to the given geometry of the sensors.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.74-84
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• 2007

This paper presents a new dual-loop Delay Locked Loop(DLL) to expand the delay lock range of a conventional DLL. The proposed dual-loop DLL contains a Coarse_loop and a Fine_loop, and its operation utilizes one of the loops selected by comparing the initial time-difference among the reference clock and 2 internal clocks. The 2 internal clock signals are taken, respectively, at the midpoint and endpoint of a VCDL and thus are $180^{\circ}$ separated in phase. When the proposed DLL is out of the conventional lock range, the Coarse_loop is selected to push the DLL in the conventional lock range and then the Fine_loop is used to complete the locking process. Therefore, the proposed DLL is always stably locked in unless it is harmonically false-locked. Since the VCDL employed in the proposed DLL needs two control voltages to adjust the delay time, it uses TG-based inverters, instead of conventional, multi-stacked, current-starved inverters, to compose the delay line. The new VCDL provides a wider delay range than a conventional VCDL In overall, the proposed DLL demonstrates a more than 2 times wider lock range than a conventional DLL. The proposed DLL circuits have been designed, simulated and proved using 0.18um, 1.8V TSMC CMOS library and its operation frequency range is 100MHz${\sim}$1GHz. Finally, the maximum phase error of the DLL locked in at 1GHz is less than 11.2ps showing a high resolution and the simulated power consumption is 11.5mW.

• Journal of Home Health Care Nursing
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• v.12 no.1
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• pp.92-116
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• 2005

Purpose: This study was a predicative survey to provide home care clients with indwelling urinary catheters for furnishing basic educational material to their families by analyzing the family members' knowledge, educational needs and educational experience about indwelling catheter management. Method : The subjects consisted of 108 family members who cared for home care clients with indwelling catheters. Data were collected by home care nurses in nine hospitals in Pusan, who directly interviewed with them through questionnaires from Sep. 6th to 30th in 2004. The questionnaires for data collection were developed through pre-survey and reference review. The collected data was analyzed by using frequency, percentile, mean, variation, t-test, ANOVA on SPSS 10.1 package. Results : There were characters of home care clients with indwelling catheters: women(67.6%) were more than men; the average age of them was $69.60{\pm}14.99$ years old; neurogenic and cerebrovascular diseases(80.0%) were the most common disease group; 81.5% of them were totally dependent on others in terms of level of activity. Home care clients' families had these characters: women(76.9%) were more than men; the average age was $54.5{\pm}13.70$ years old; 46.3% of them were parents or sons or daughters in terms of relation with patient; tl1e average care period was $39.8{pm}34.20$ months. Level of knowledge about indwelling catheter management of the family members were 69.8% and its mean were $20.24{\pm}4.53$. Educational needs were 90.9% and its mean were $14.55{\pm}3.56$. Educational experience were 53.3% and its mean were $8.53{\pm}4.30$. 'Complications in using an indwelling catheter', 'Symptoms to call for a home care nurse' and 'Method to attach an indwelling catheter' were high ranked in both educational needs and educational experience. 'Anatomy of urinary tract', 'Functions of urinary tract' and 'Catheter placement' were low ranked in both educational needs and educational experience Level of knowledge about indwelling catheter management of the families showed a significant difference according to their age(F=5.35, p=0.01). Educational needs showed a significant difference according to care period(F=3.06, p=0.04). Conclusion: the family members' level of knowledge and educational experience about indwelling catheter management and their educational were not sufficient while their educational needs were high. In other words although the family members were acknowledged education needs, but the care for the patients with indwelling catheter weren't performed well because of their lack of related knowledge. Therefore systematic educational programs about indwelling catheter management for home care clients and their families should be made on the base of this study.

• Journal of the Korean Home Economics Association
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• v.46 no.9
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• pp.99-112
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• 2008

The increasing rate of obesity in school aged children has become a conspicuous social phenomenon in Korea. This has been linked to greater economic growth, increasingly westernized dietary habits, and a consumer driven society. Given that obesity can lead to social exclusion or unfavorable attention by other students in a school setting, the design of plus-size garments have become important for effective appearance management skills. This research aimed to establish a somatotype database for obese school boys, aged 10 to 12, in order to develop a sizing system for plus-size upper garments. In order to measure somatotype of average and obese school boys, five categories were recorded; height, obesity, length of trunk, thickness of neck and chest. For obese boys, subcutaneous fat thickness and position of B.P/shoulder point factors were recorded. Obesity factor was subdivided into overall and specific ones, and while the deviation of obese body types was severe compared to the average type. Obese body type showed significantly higher measurements in width, girth, thickness. This is linked to the fact that the frequency ratio of obesity increases with age. Stature and chest were chosen as control dimensions for boys' wear. As crosstabulation of stature(5cm interval) and chest girth(2, 3 and 4cm), and stature(5cm interval)/chest girth(3cm interval) sizing system showed, the most effective cover ratio and adaptability to the data distribution $25{\sim}75$ quartile. Based on the findings, 10 sizes were formulated for average body type, while 18 sizes were formulated for obese type, whose size cover ratios were 48% and 62.9%, respectively. The primary ranges of stature were $145cm{\sim}150cm$, while those of chest girth were $79{\sim}82cm$. Each size was declared as "chest-somatotype{A(average)/O(obesity)-stature". This study proposed a plus-size upper garment sizing systems for obese boys, accompanied with reference measurements for suit, casual wear and underwear. The finding showed that the two systems were totally separate and not overlapping, meaning that plus-size sizing system is essential for obese school boys. The obesity type system had more size and wider range specs.