• Communications for Statistical Applications and Methods
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• v.26 no.2
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• pp.91-102
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• 2019

In this paper, we propose a new estimation method based on a weighted linear regression framework to obtain some estimators for unknown parameters in a two-parameter Rayleigh distribution under a progressive Type-II censoring scheme. We also provide unbiased estimators of the location parameter and scale parameter which have a nuisance parameter, and an estimator based on a pivotal quantity which does not depend on the other parameter. The proposed weighted least square estimator (WLSE) of the location parameter is not dependent on the scale parameter. In addition, the WLSE of the scale parameter is not dependent on the location parameter. The results are compared with the maximum likelihood method and pivot-based estimation method. The assessments and comparisons are done using Monte Carlo simulations and real data analysis. The simulation results show that the estimators ${\hat{\mu}}_u({\hat{\theta}}_p)$ and ${\hat{\theta}}_p({\hat{\mu}}_u)$ are superior to the other estimators in terms of the mean squared error (MSE) and bias.

• Journal of Ocean Engineering and Technology
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• v.33 no.3
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• pp.229-235
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• 2019

In this study, a two-dimensional oscillating foil with forward speed in a propagating wave flow field was considered. The time-mean power to maintain the heaving and pitching motions of the foil was analyzed using the perturbation theory in an ideal fluid. The power, which was a non-linear quantity of the second-order, was expressed in terms of the quadratic transfer functions related to the mutual product of the heaving and pitching motions and incoming vertical flow. The effects of the pivot point and phase difference among the disturbances were studied. The negative power, which indicates energy extraction from the fluid, is shown as an example calculation.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.67-73
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• 2021

The need for precise location data is growing across numerous markets, and so is the number of affordable high-precision GPS receivers. In this paper, we validated the performance of RTAP2U, a low-cost high-precision RTK receiver that was recently released. Two positioning modes were tested: static and driving. The static test conducted Zero-Baseline Single-RTK and Network-RTK survey for 57 hours and 51 hours, respectively. For the driving test, Network-RTK survey was conducted using VRS services provided by NGII based on Trimble PIVOT and Geo++ GNSMART. The static test showed about 1 cm horizontal and vertical accuracies, which is very stable considering the test duration longer than 50 hours. The integer ambiguity FIX rate marked a solid 100%. The driving test result also reached a 100% FIX rate. Horizontal and vertical accuracies were better than 2 cm and 3 cm, respectively. Researchers can refer to this paper when considering affordable high-precision GPS receivers as an option.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.307-310
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• 2013

본 논문은 한국어-스페인어와 한국어-불어 간의 양방향 이국어 사전(Bi-directional bilingual lexicon)을 자동으로 구축하기 위한 새로운 방법을 제안한다. 일반적으로 한국어와 스페인어/불어 간의 병렬 말뭉치를 직접적으로 구축하기에는 어려움에 따르기 때문에, 영어를 중심언어로 하는 영어(EN)-한국어(KR)/스페인어(ES)/불어(FR) 병렬 말뭉치를 이용하여 문맥 벡터를 만들고 그들 간의 유사도를 계산하는 변형된 문맥 벡터 방법을 제안한다. 영어는 다른 언어와의 이국어 병렬 말뭉치가 비교적 많이 공개되어 있기 때문에 이 방법을 이용하면 비교적 쉽게 KR-ES와 KR-FR 양방향 이국어 사전을 구축할 수 있다. 본 논문에서 제안한 방법으로 실험해본 결과 최고 85%(ES${\rightarrow}$KR)의 정확도를 얻을 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.397-400
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• 2010

우리는 지난 연구에서 변형 비속어 필터링 시스템을 위하여 근사 문자열 검색 시스템을 적용하여 서열 정렬 횟수를 비약적으로 줄일 수 있었다. 다차원 데이터 구조를 이용한 한글 근사 검색 시스템은 기준축인 Base-Pivot의 숫자에 따라 검색 결과의 정확도를 높일 수 있으나 BP이 증가한 만큼 질의 단어의 좌표를 계산하기 위한 시간이 오래 걸린다. 소규모 데이터 검색에는 문제가 되지 않으나 60,000단어 이상의 데이터가 수록되는 국어사전과 같은 대규모 데이터를 검색하게 될 경우 요구되는 BP의 숫자도 증가하여 많은 연산시간을 필요로 한다. 본 논문에서는 기존의 근사 단어 검색 시스템을 계층구조화 하여 요구되는 BP 숫자를 감소 시켜 성능을 향상 시키는 방법을 제안하고자 한다. 그리고 실험을 통하여 본 아이디어의 실효성을 증명하였다. 본 아이디어는 기존의 6000개의 비속어에 대하여 약 20%정도의 성능향상을 보였다.

• SUVANNABHUMI
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• v.9 no.1
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• pp.7-52
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• 2017

This paper analyzes the scholarly approaches to the problem of "local" vs. "cosmopolitan" in the context of the cultural transfers between South and Southeast Asia. Taking the "localization" paradigm advanced by Oliver Wolters as its pivot, it reviews the "externalist" and "autonomous" positions, and questions the hermeneutical validity of the fuzzy and self-explanatory category of "local." Having discussed the geo-environmental metaphors of "Monsoon Asia" and "Maritime Asia" as alternative paradigms to make justice to the complex dynamics of transregional interaction that shaped South and Southeast Asian societies, it briefly presents two case studies highlighting the tensions between the "local" and "cosmopolitan" approaches to the study of Old Javanese literature and Balinese Hinduism.

• Current Optics and Photonics
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• v.8 no.3
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• pp.300-306
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• 2024

To solve the nozzle swing angle non-contact measurement problem, we present a nozzle pose estimation algorithm involving weighted measurement uncertainty based on rotation parameters. Firstly, the instantaneous axis of the rocket nozzle is constructed and used to model the pivot point and the nozzle coordinate system. Then, the rotation matrix and translation vector are parameterized by Cayley-Gibbs-Rodriguez parameters, and the novel object space collinearity error equation involving weighted measurement uncertainty of feature points is constructed. The nozzle pose is obtained at this step by the Gröbner basis method. Finally, the swing angle is calculated based on the conversion relationship between the nozzle static coordinate system and the nozzle dynamic coordinate system. Experimental results prove the high accuracy and robustness of the proposed method. In the space of 1.5 m × 1.5 m × 1.5 m, the maximum angle error of nozzle swing is 0.103°.

• Journal of the Korean Arthroscopy Society
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• v.9 no.2
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• pp.148-153
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• 2005

Purpose: To analyze the clinical result of the arthroscopic reduction and fixation for the displaced tibial spine fractures in children and report the utility of the arthroscopic treatment with the review of the literature. Methods: Between December 2000 and July 2004, five patients (average age 9.1 years) received an arthroscopic reduction and fixation of displaced tibial spine fracture. A male-to-female ratio was 3:2 and mean follow-up was 38.2$(13{\sim}56)$ months. All five patients were classified type III by Movers and McKeever classification. The average period from injury to operation was 4.8 days $(3{\sim}8days)$, the avulsed fragment was reduced by operative arthroscopy and fixated by pull-out suture in 3 patients and by cannulated screw in 2 patients. Postoperatively long leg cast was applied for 2 weeks, and then gradual range-of-motion exercise was permitted. Full weight-bearing ambulation was permitted after 6 weeks. The clinical evaluation was performed by range of motion, Lachman and pivot shift test, KT-1000 arthrometer, Lysholm knee score and the modified Feagin score. Results: All five patients had no symptom and recovered full range of motion of the affected knees. Lachman test was positive finding of 1+ laxity in one patient, the others were negative, and all patients were negative findings for pivot shift test. The result of KT-1000 arthrometric assessment is mean maximum side-to-side differences 1.9 mm. Average Lysholm knee score was 99.4. All patients had excellent results in modified Feagin score. Conclusion: Arthroscopic reduction and fixation of displaced tibial spine fracture in children showed excellent result without complication. Both pull-out suture fixation and cannulated fixation provide an effective treatment option for fixation of the displaced anterior tibial spine fracture.

• Journal of the Korean Arthroscopy Society
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• v.9 no.2
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• pp.143-147
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• 2005

Purpose: In case of anterior cruciate ligament (ACL) reconstruction, graft tendon is generally fixed in tibial tunnel with knee extended. When reconstructing ACL using hamstring tendon, the authors aim to find out the effect of knee joint position during graft fixation on postoperative knee joint stability and range of motion. Materials and Methods: Prospective study was done on patients who have undergone ACL reconstruction using hamstring tendon from May 2002 to January 2003 We used Rigifix system (Mitek Product, Johnson and Johnson, USA) and Intrafix system for fixation. Thirty nine patients received ACL reconstruction during this period. Excluding 2 patients lost in the follow-up, 37 patients were analyzed. The mean follow-up period was 14 months $(13{\sim}25months)$. Knee position was decided alternatively without any bias. Clinical evaluation was based on Lachman test, pivot shift test, Lysholm score, IKDC(international knee documentation committee) assessment and side to side KT-1000 maximal manual arthrometer difference. Results: After the last follow-up, average postoperative Lysholm score was 93.1 poins(65-98points). According to IKDC score, 26 cases were normal, 10 cases were nearly normal, 1 case was abnormal and we had no case of severe abnormality. The mean difference from the normal side was 2.5 mm under maximal manual loading KT-1000 arthrometer. According to postoperative Lachman test, 32 cases were normal,2 cases were grade I and 1 case was grade II. There were 34 cases of normal, 2 cases of grade I and 1 case of grade II. When using maximal manual KT-1000 arthrometer side to side difference, the difference from the normal side while fixing the tibia at 20'knee flexion was 2.3 mm and at full extention the difference was 2.7 mm. The range of motion at postoperative 1 year showed 5 degree flexion contracture in 1 case at 20 degrees knee flexion and 10 degrees of flexion limitation was observed in 2 cases at full extension. Conclusion: When ACL reconstruction using autogenous hamstring tendon, anterior laxity showed no difference in its stability between two groups. Tibial side fixation at full extension may be helpful in preventing flexion contracture due to overconstrained graft tendon.

• Journal of the Korean Arthroscopy Society
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• v.12 no.1
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• pp.1-6
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• 2008

Purpose: The purpose of this study is to compare the results of the arthroscopic reconstruction of ACL using autologous hamstring tendon and autologous bone-patellar tendon-bone. Materials and Methods: From January, 2000 to December, 2004, 120 patients underwent arthroscopic ACL reconstruction using autologous hamstring tendon(60 cases) and autologous bone-patellar tendon-bone(BPTB)(60 cases). The mean followed up period of hamstring tendon group was 42 months(range $24{\sim}69$ months) and patellar tendon group was 52 months(range $24{\sim}84$ months). At the time of the final follow up, sixty patients in each group were evaluated the results of physical examination, activity level, patients' satisfaction, functional status, and objective anteriror stability using KT-2000 arthrometer. Results: At the time of the final follow up we compared the two groups who had ACL reconstruction using either autologous hamstring tendon or BPTB, and the final results of the Lachman test showed negative, or mildly positive in 85%(51 cases) of the hamstring tendon group and 90%(54 cases) of the BPTB group. Pivot shift test indicated positive in both groups, 8%(5 cases) and 5%(3 cases) respectively and showed no statistically significant difference. The evaluation of the anterior laxity using the KT-2000 arthrometer revealed no significant difference in the hamstring and BPTB groups: differences less than 3 mm compared to the healthy side were 85%(51 cases) and 90%(54 cases)(p>0.05). The Lysholm score improved from a preoperative score of 51 to a postoperative score of 79.1 in the hamstring groups and from 52 to 82.2 in the BPTB groups. According to the IKDC rating system, 87%(52 cases) were normal or near normal in the hamstring group. In the BPTB group, 83%(50 cases) were normal or near normal. The Tegner score for the hamstring groups was 4.8 preoperatively and 7.1 at the final follow up, and the Tegner score for the BPTB groups was 4.5 preoperatively and 7.3 after the last follow-up. The anterior knee pain was found in 7%(4 cases) in the hamstring tendon group and 10%(6 cases) in the patellar tendon group. Conclusion: Arthroscopic ACL reconstruction using both the autologous hamstring tendon and the patellar tendon during their mid term follow up period demonstrated excellent results. However, the final results during their last follow up showed no statistically significant difference between the two groups.