• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.29-38
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• 2024

The Matched Field Processing (MFP) is an estimation method for a source range and depth based on the prediction of sound propagation. However, as the frequency increases, the prediction inaccuracy of sound propagation increases, making it difficult to estimate the source position. Recently proposed, the Frequency-Difference Matched Field Processing (FD-MFP) is known to be robust even if there is a mismatch by applying a frequency-difference autoproduct extracted from the auto-correlation of a high frequency signal. In this paper, in order to evaluate the performance of the FD-MFP using a horizontal line array, simulations were conducted in the environment of the East Sea of Korea. In the area of Bottom Bounce (BB) and Convergence Zone (CZ) where detection of a sound source is possible at a long range, and the results of localization were analyzed. According to the the FD-MFP simulations of horizontal line array, the accuracy of localization is similar or degraded compared to the conventional MFP due to diffracted field and mismatch of sound speed. There was no clear result from the simulations conforming that the FD-MFP was more robust to mismatch than the conventional MFP.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.374-383
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• 2010

Microwave radar can penetrate cloud cover regardless of weather conditions and can be used day and night. Especially a ground-based polarimetric scatterometer has advantages of monitoring crop conditions continuously with full polarization and different frequencies. Kim et al. (2009) have measured backscattering coefficients of paddy rice using L-, C-, X-band scatterometer system with full polarization and various angles during the rice growth period and have revealed the necessity of near-continuous automatic measurement to eliminate the difficulties, inaccuracy and sparseness of data acquisitions arising from manual operation of the system. In this study, we constructed an X-band automatic scatterometer system, analyzed scattering characteristics of paddy rice from X-band scatterometer data and estimated rice growth parameter using backscattering coefficients in X-band. The system was installed inside a shelter in an experimental paddy field at the National Academy of Agricultural Science (NAAS) before rice transplanting. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables and personal computer that controls frequency, polarization and data storage. This system using automatically measures fully-polarimetric backscattering coefficients of rice crop every 10 minutes. The backscattering coefficients were calculated from the measured data at a fixed incidence angle of $45^{\circ}$ and with full polarization (HH, VV, HV, VH) by applying the radar equation and compared with rice growth data such as plant height, stem number, fresh dry weight and Leaf Area Index (LAI) that were collected at the same time of each rice growth parameter. We examined the temporal behaviour of the backscattering coefficients of the rice crop at X-band during rice growth period. The HH-, VV-polarization backscattering coefficients steadily increased toward panicle initiation stage, thereafter decreased and again increased in early-September. We analyzed the relationships between backscattering coefficients in X-band and plant parameters and predicted the rice growth parameters using backscattering coefficients. It was confirmed that X-band is sensitive to grain maturity at near harvesting season.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.185-188
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• 2009

Purpose: Standard of retests were discrepant and inconsistent due to inaccuracy and lack of standardization within normal range limit of tumor marker test. To enhance the standardization of retests set standard value below normal range and the Order Communication System Quality Control (OCS QC) program was put in place. This program enables managing the results within lower limit of normal range which were used for tumor marker test in Health Center. Materials and Methods: At present the tumor marker study for AFP, CEA, CA19-9, CA125, and PSA included outpatients in Asan Medical Center from February to March, 2009. The standard value was obtained by using the percentage of CV of Inter Assay according to the normal range of each tumor test. The results were confirmed by using the OCS QC program via formatted assessment of screening test such as test items, standard value and medical department. The number of out-of-range results within plus and minus 30 percents regarding the five primary items of tumor marker test was assessed. The next step was to obtain the number of AFP, CEA, and CA125 according to the ratio of comparison between prior and post test result, 60%, 50%, and 40% within normal range, respectively. In addition, set standard value below normal range. Results: The first screening test with percentage of sample number was resulted between 30%-40% and the second one was AFP 26.1%, CEA 18.9%, CA19-9 17.3%, CA125 18.7%, and PSA 21.0% obtained screening percentage of average 20 percents. The limited value of retest was AFP less than 5.0 and more than 10.0, CEA less than 1.0 and more than 3.0, CA19-9 less than 10.0 and more than 30.0, and PSA less than 1.0 and more than 2.0 to set and the number of retest was obtained by applying to the limited value of retest to screening percentage of average 20 percents For two months, the number of retest was AFP 0, CEA 15, CA19-9 3, CA125 2, and PSA 5. Conclusions: Through using the OCS QC program in establishing the standard of retest systemically, there appeared to be reduced discrepancy among the examiners and to be expected improvement in relation to the error of results.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.86-91
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• 2009

Purpose: The whole body scan in Nuclear Medicine is a widely accepted examination and procedure. Especially, it is mainly used in bone, I-131, MIBI, and HMPAO WBC scans. The diverse uses of the whole body scan range from the HMPAO WBC scan with a speed of 13cm/min, to a whole body bone scan using the Onco. Flash technique with a speed of 30cm/min. The accuracy of table movement has a strong correlation with the image quality, and inaccuracy of speed could negatively affect the image quality. The purpose of this study is to evaluate the accuracy of the table movement while considering the influence of the age of the equipment and the variability in the weight of the patients. Material and Methods: The study was conducted using two of Seoul Asan Medical Center's SIEMENS gamma cameras which are commonly used in our whole body study. The first one is the oldest gamma camera, an ECAM plus (installed in 2000), and the last is brand new one, a SYMBIA T2 (installed in 2008). Three trials were conducted with the tables moving at a different speed each time; 10, 15 and 30 cm/min. The tables' speeds were measured by checking how long it took for the table to move 10cm, and this was repeated every 10cm until the table reached 100 cm. With an average body weight of the patients of about 60~70 kg, the table speed was measured with weights of 0 kg, 66 kg and 110 kg placed on the table, then compared among conditions. Results: The coefficient of variance (CV) of the ECAM plus showed 1.23, 1.42, 2.02 respectively when the table movement speeds were set at 10, 15, and 30 centimeters per minute. Under the same conditions, the SYMBIA T2 showed 1.23, 1.83 and 2.28 respectively. As table movement speed more, the variance of CV as the speed increases. When the patient body weight was set to 0, 66 and 110kg, the CV values of both cameras showed 0.96, 1.45, 2.08 (0 Kg), 1.32, 1.72, 2.27 (66 Kg) and 1.37, 1.73, 2.14 (110 Kg). There was no significant difference (p>0.05) in 95 percent of confidence intervals and measured CV values were acceptable. However, the CV value of the SYMBIA T2 was relatively larger than the ECAM plus. Conclusion: The scan speed of the whole body scan is predetermined based on which examination is being performed. It is possible for the accuracy of the speed to be affected, such as the age of the equipment, the state of the bearings or the weight of a patient. These factors can have a negative impact on the diagnostic consistency and the image quality. Therefore, periodic quality control should be needed on the gamma cameras currently being used, focusing on the table movement speed in order to maintain accuracy and reproducibility.

• Journal of the Korean Arthroscopy Society
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• v.3 no.1
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• pp.17-23
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• 1999

Purpose : We intend to review clinical results after Anterior cruciate ligament(ACL) reconstruction using hamstring tendon arthroscopically. Materials & Methods : Sixty two patients who had underwent arthroscopic ACL reconstruction using hamstring tendon from Mar. 1996 to Mar. 1997 were reviewed. The average follow-up was 16 months and average age at operation was 27 years old. Clinical results were evaluated with physical examination, Lysholm Knee score and instrumented anterior laxity test with Telos Results : The average preoperative Lysholm knee score was 57.0 and postoperative average of that was 91.8. All cases of 62 patients had normal range of motion of knee and were able to walk with no problems at follow-up. On the Lachmann test, there were mild(+) instability in 24 cases, moderate(++) in 24 cases, severe(+++) in 14 cases preoperatively and 48 cases were converted to negative, 14 cases mild postoperatively. On instrumented anterior laxity test with Telos, difference between normal and affected knee on 20 lb which was 13.4mm preoperatively was decreased to 4.7mm at follow-up and anterior stability was regained(P<0.05). Parapatellar complications such as crepitus in 18 cases(29.5%), atrophy of quadriceps in 23 cases(36.5%) were observed. There were 2 cases of inaccuracy of guide pin of semifix screw intraoperatively and 3 cases of malposition of semifix screw postoperatively. Conclusion : ACL reconstruction using hamstring tendon seems to be a effective procedure to establish the stability of knee joint but is technically demanding procedure and leaves some parapatellar complications.

• Progress in Medical Physics
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• v.15 no.3
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• pp.161-166
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• 2004

A simplistic quality assurance (QA) method was designed for a Linac built-in enhanced dynamic wedge (EDW), which can be utilized to make wedged beam distributions. For the purpose of implementing the EDW symmetry QA, a film dosimetry system, low speedy dosimetry film, film densitometer and 3D RTP system were used, and the films irradiated by means of a 60$^{\circ}$ Reversed wedge pair (REWP) method. The profiles were then analyzed in terms of their symmetries, including partial treatment, which is the case of stopping it abruptly during EDW irradiation, and the measured and calculated values compared using the Cad Plan Golden Segmented Treatment Table (Golden STT). The result of this experiment was in good agreement, within 1 %, of the 'reversed wedge pair counterbalance effect'. For the QA of the effective wedge factor (EWF), the authors measured EWFs in relation to the 10$^{\circ}$, 15$^{\circ}$, 20$^{\circ}$, 25$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$ and 60$^{\circ}$ EDW, which were compared with the calculated values using the correction factor derived from the Golden STT and the log files produced automatically during the process of EDW irradiation. By means of this method it was capable of check up the safety of effective wedge factor without any other dosimetry system. The EDW QA was able to be completed within 1 hour from irradiation to analysis as a consequence of the simplified QA procedure, with maximized effectiveness. Unlike the metal wedge system, the EDW system was heavily dependent on the dose rates and jaw movements; therefore, its features could potentially cause inaccuracy. The frequent simplistic QA for the EDW is essential, and could secure against the flaw of dynamic treatment that uses the EDW.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.377-391
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• 2018

In order to efficiently monitor red tide over a wide range, the need for red tide detection using remote sensing is increasing. However, the previous studies focus on the development of red tide detection algorithm for ocean colour sensor. In this study, we propose the use of multi-sensor to improve the inaccuracy for red tide detection and remote sensing data in coastal areas with high turbidity, which are pointed out as limitations of satellite-based red tide monitoring. The study area were selected based on the red tide information provided by National Institute of Fisheries Science, and spatial fusion and spectral-based fusion were attempted using GOCI image as ocean colour sensor and Landsat OLI image as terrestrial sensor. Through spatial fusion of the two images, both the red tide of the coastal area and the outer sea areas, where the quality of Landsat OLI image was low, which were impossible to observe in GOCI images, showed improved detection results. As a result of spectral-based fusion performed by feature-level and rawdata-level, there was no significant difference in red tide distribution patterns derived from the two methods. However, in the feature-level method, the red tide area tends to overestimated as spatial resolution of the image low. As a result of pixel segmentation by linear spectral unmixing method, the difference in the red tide area was found to increase as the number of pixels with low red tide ratio increased. For rawdata-level, Gram-Schmidt sharpening method estimated a somewhat larger area than PC spectral sharpening method, but no significant difference was observed. In this study, it is shown that coastal red tide with high turbidity as well as outer sea areas can be detected through spatial fusion of ocean colour and terrestrial sensor. Also, by presenting various spectral-based fusion methods, more accurate red tide area estimation method is suggested. It is expected that this result will provide more precise detection of red tide around the Korean peninsula and accurate red tide area information needed to determine countermeasure to effectively control red tide.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.1
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• pp.29-36
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• 2020

This study was conducted to suggest the new grassland grade system on evaluating the grassland status. The grassland status has been evaluated based on the forage yield (good, fair and poor) by municipal authorities. The grassland grades by current system were 19 good, 11 fair and 11 poor among the 41 grassland farms from 6 provinces. This evaluation result differed greatly from the result of actual measurement of forage yields which showed all poor. The big difference was resulted from failing the reflection of the various characteristics, such as different seasonal growth and harvest frequency. Furthermore, the lack of consistent examining date and method added the inaccuracy of current grassland grade system. The new grassland grade system based on the grassland vegetation ratio (grass, weed and bare soil) was initially designed into 6-grade system (1st; 100~80%, 2nd; 79~60%, 3rd; 59~40%, 4th; 39~20%; 5th; 19~1% and 6th; 0% on the basis of grasses proportion), but later was changed into 4-grade system (1st, 2nd, 3rd, and 4th grades are 70% or more, 50% or more, 50% or less, and 0% of forage proportion, respectively) after reflecting the opinion of grassland farms and municipal authorities. Re-evaluation on the grassland status using the 4-grade system resulted in the total 80% consisted of 2nd, 3rd and 4th grade which means most grasslands needs the partial reseeding or the rehabilitation of entire grassland. Pictures and schematic diagrams depicting the 4-grade system were presented to improve the objectivity of evaluation. The optimal time for assessing grassland status is fall when plant height 20~30 cm. Conclusively, the 4-grade system is an efficient method for all non-professionals including grassland farms or municipal authorities in assessing the grassland status. To apply this system to the field, the institutional arrangements such as amendment of grassland act should take place in advance.

• Korea journal of population studies
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• v.15 no.2
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• pp.15-59
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• 1992

After world war II Japanese life expectancy has been improved remarkably, and reached the highest level in the world around late 1970's. The life expectancy of Korean has also shown tremendous improvement in recent years with about 20 year's gap from the Japanese. The reason of rapid improvement of life expectancy can be explained by changes in the structure of cause of death due to health system, living standard, social welfare, health behavior of individuals and so on. Korean in Japan is placed under different situations from both Korean in Korea and Japanese in these regards, and expected to show different picture of cause of death pattern. The objective of this study is the comparision of changing patterns of cause of death of three population groups, Korean in Japan, Korean in Korea and Japanese, and to investigate the reasons which effect to the structural difference of mortality cause with special emphasis on health ecological aspects. One of the major limitations of the Korean causes of death statistics is the under-registration which ranges about 10% of the total events, and inaccuracy of the exact cause of death. Some 20% of registered deaths were unable to classify by ICD. However, it is concluded that the Korean data are evaluated as sufficient to stand for over-viewing of trends of cause of death pattern. The evaluation is done by comparing data from registration and field survey over the same population sample. Population data of Korean in Japan differ between two sources of data; census and foreigner's registration. Correction is done by life table method under the assumption that age-specific mortality pattern would accord with that of the Japanese. The crude death rate was lowest among Korean in Japan, 5.7 deaths per 1,000 population in 1965. The crude death rates of Korean in Japan and Japanese are increasing recently influenced by age structure while Korean in Korea still shows decreasing tendency. The adjusted death rate is lowest among Japanese, followed by Korean in Japan, and Korean in Korea. The leading causes of death of Korean in Korea until 1960's was infectious diseases including pneumonia and tuberculosis. The causes of death structure changed gradually to accidents, neoplasm, hypertensive disease, cerebro-vascular disease in order. The main difference in cause of death between Korean and Japanese if high rate of liver diseases and diabetes for both Korean in Japan and Korea. A special feature of cause of death among Korean in Korea is remakably high rate of hypertensive disease, which is assumed to be caused by physicians tendency in choosing diagnostic categories. The low ischemic heart disease and high vasculo-cerebral disease are the distinctive characteristic of the three population groups compared to western countries. Specific causes of death were selected for detailed sex, age and ethnic group comparisons based on their high death rates. Cancer is the cause of death which showed most dramatical increase in all three population groups. In Korea 20.1% of all death were caused by cancer in 1990 compared with 10.5% in 1981. Cancer of the liver is the leading cause of cancer death among Korean in Japan for both sexes, followed by cancer of the lung and cancer of the stomach, while that of Korean in Korea is cancer of the stomach, followed by cancer of the liver and cancer of the lung for male. Causes of infant mortality were examined among the three population groups since 1980 on yearly bases. For both Japanese and Korean in Japan, leading cause of death ranks as conditions originating in the perinatal period, congenital anomalies, accidents and other violent causes. Trends since 1980 for these two population groups in the leading cause of infant mortality showed no changes. On the contrary, significant changes in leading cause of death structure in Korea were observed : the ranking of leading cause of death in 1981 were congenital asnomalies, pneumonia bronchitis, infectious disease, heart disease, conditions originating in the perinatal period, accident and other violent causes ; in 1990 the ranking shifted to congenital anomalies, accident, pneumonia bronchities, conditions originating in the perinatal period, infectious disease. The mortality rate by congenital anomalies in Korea continuously grew than any other causes. Larger increase ocurred during the 1990's

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.4
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• pp.9-21
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• 2008

In this paper, we propose a GNSS-based RF receiver, A high precision localization architecture, and a high sensitivity localization architecture in order to solve the satellite navigation system's problem mentioned above. The GNSS-based RF receiver model should have the structure to simultaneously receive both the conventional GPS and navigation information data of future-usable Galileo. As a result, it is constructed as the multi-band which can receive at the same time Ll band (1575.42MHz) of GPS and El band (1575.42MHz), E5A band (1207.1MHz), and E4B band (1176.45MHz) of Galileo This high precision localization architecture proposes a delay lock loop with the structure of Early_early code, Early_late code, Prompt code, Late_early code, and Late_late code other than Early code, Prompt code, and Late code which a previous delay lock loop structure has. As we suggest the delay lock loop structure of 1/4chips spacing, we successfully deal with the synchronization problem with the C/A code derived from inaccuracy of the signal received from the satellite navigation system. The synchronization problem with the C/A code causes an acquisition delay time problem of the vehicle navigation system and leads to performance reduction of the receiver. In addition, as this high sensitivity localization architecture is designed as an asymmetry structure using 20 correlators, maximizes reception amplification factor, and minimizes noise, it improves a reception rate. Satellite navigation system repeatedly transmits the same C/A code 20 times. Consequently, we propose a structure which can use all of the same C/A code. Since this has an adaptive structure and can limit(offer) the number of the correlator according to the nearby environment, it can reduce unnecessary delay time of the system. With the use of this structure, we can lower the acquisition delay time and guarantee the continuity of tracking.