• Journal of the Korean Society for Nondestructive Testing
• /
• v.31 no.5
• /
• pp.522-528
• /
• 2011

Artificial basilar membranes made of PVDF(polyvinylidene fluoride) are manufactured using microfabrication processes. The mechanical behavior of PVDF artificial basilar membrane was measured to evaluate its performance as a mechanical frequency analyzer using scanning LDV(laser Doppler vibrometer). The experimental setup consists of the microfabricated artificial basilar membrane, a loud speaker connected to an amplifier for generating acoustic pressure of specific spectral pattern, and a scanning LDV with controlling unit for measuring the displacement of the membrane on the incoming acoustic stimulation. The microfabricated artificial basilar membrane was attached tightly upon a package containing a chamber which can be filled with silicone oil before placed on the experimental setup stage. The experiment results showed that the microfabricated artificial basilar membrane has a property as a mechanical frequency analyzer.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.6 no.5
• /
• pp.416-422
• /
• 2001

The BLDC(Brushless DC) Motor is characterized by linear torque to current and speed to voltage. It has low acoustic noise and fast dynamic response. Moreover, it has high power density with high proportion of torque to inertia in spite of small size drive. However, when armature current is commutated, the current ripple is generated by the motor inductance components in stator windings and back-EMF. This current ripple caused to torque ripple. Therefore, it is difficult to apply the BLDC motor to a precision servo drive system. In this paper, a new current control algorithm using fourier series coefficients is proposed. This proposed algorithm can minimize torque ripple due to the phase current commutation of BLDC motor. Simulation and Experimental results prove the effectiveness at the Proposed algorithm through comparison with the conventional unipolar PWM method.

• The Transactions of the Korea Information Processing Society
• /
• v.13 no.3
• /
• pp.140-147
• /
• 2024

In the Republic of Korea, people with hearing impairments are the second-largest demographic within the registered disability community, following those with physical disabilities. Despite this demographic significance, research on sign language translation technology is limited due to several reasons including the limited market size and the lack of adequately annotated datasets. Despite the difficulties, a few researchers continue to improve the performacne of sign language translation technologies by employing the recent advance of deep learning, for example, the transformer architecture, as the transformer-based models have demonstrated noteworthy performance in tasks such as action recognition and video classification. This study focuses on enhancing the recognition performance of sign language translation by combining transformers with 3D-CNN. Through experimental evaluations using the PHOENIX-Wether-2014T dataset [1], we show that the proposed model exhibits comparable performance to existing models in terms of Floating Point Operations Per Second (FLOPs).

• Journal of the Korean Society of Radiology
• /
• v.16 no.7
• /
• pp.879-887
• /
• 2022

In this study, we tried to confirm whether the mechanical sequential elevation method of the body pressure measuring bed actually induces segmental motion for each part of the spine. To this end, a lateral X-ray examination was performed, and it was confirmed that the sequential pressure device induces a step-wise segmentation of the spine by mechanically lifting each part of the spine vertically. Then, pain, walking ability, and depression scale were measured and analyzed in subjects who were aware of back pain. VAS(p<0.05) and ODI(p<0.05) for 10 days tended to decrease in average after bed use. In the gait ability test(p<0.05), as the number of times of bed use increased, the moving time in the test decreased and the moving distance increased. In addition, GSDDF(p<0.05) decreased after bed use. As a result, it was confirmed that the spinal segmentation caused by the heat and acupressure provided by the bed affected gait and depression as well as pain relief.

• The Journal of Korean Academy of Sensory Integration
• /
• v.19 no.1
• /
• pp.69-82
• /
• 2021

Objective : This recent work intended to provide basic information for researchers and practitioners related to occupational therapy about Developmental Coordination Disorder (DCD) in South Korea. The previous research of screening DCD and the effects of intervention programs were reviewed. Methods : Peer-reviewed papers relating to DCD and published in Korea from January 1990 to December 2020 were systematically reviewed. The search terms "developmental coordination disorder," "development coordination," and "developmental coordination" were used to identify previous Korean research in this area from three representation database, the Research Information Sharing Service, Korean Studies Information Service System, and Google Scholar. We found a total of 4,878 articles identified through the three search engines and selected seventeen articles for analysis after removing those that corresponded to the overlapping or exclusion criteria. We adopted "the conceptual model" to analyze the selected articles about DCD assessment and intervention. Results : We found that twelve of the 17 studies showed the qualitative level of Level 2 using non-randomized approach between the two groups. The Movement Assessment Battery for Children and its second edition were the most frequently used tools in assessing children for DCD. Among the intervention studies, the eight articles (47%) were adopted a dynamic systems approach; a normative functional skill framework and cognitive neuroscience were each used in 18% of the pieces; and 11% of the articles were applied neurodevelopmental theory. Only one article was used a combination approach of normative functional skill and general abilities. These papers were mainly focused on the movement characteristics of children with DCD and the intervention effect of exercise or sports programs. Conclusion : Most of the reviewed studies investigated the movement characteristics of DCD or explore the effectiveness of particular intervention programs. In the future, it would be useful to investigate the feasibility of different assessment tools and to establish the effectiveness of various interventions used in rehabilitation for better motor performance in children with DCD.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.92-92
• /
• 2019

최근 기존의 격자방식의 해석 방법을 벗어나 해석 영역에 대한 분할을 별도로 고려치 않는 수치기법의 실무적 적용사례가 증가 하고 있으며, 이러한 방식중 SPH(Smoothed Particle Hydrodynamics) 방식이 근자에 수자원 분야에서도 도입되어 관수로 및 개수로 해석 또는 복합해석 등에 활용된 바 있다. 최초 도입된 무격자방식의 모형들은 주로 복잡한 형상을 지니는 유체기계 등에 활용성이 높았던 바, 큰 규모의 해석 도메인을 가지는 수자원 분야에서의 SPH의 실무적용 평가와 효율성의 확보를 위해서, 본 연구는 국내 댐을 시범 대상으로 하여 SPH 수치해석 툴을 적용하고자 하였다. 분석 대상댐은 국내 P댐으로서 관리수위의 변동은 크지 않으나, 댐 직상류의 만곡이 심하고 다수의 대규모 취수구를 가진 곳으로 상시 발전방류 및 수시 댐 수문방류에 의해 유체의 흐름이 2,3차원의 복잡성을 띄고있기 때문에, 3차원 전산유체역학 Tool의 적용이 적절한 것으로 판단하였다. 해석을 위해 하류경계조건을 댐축과 문비로 설정하였고 상류 1km까지를 해석의 도메인으로 설정하였다. 소요시간을 줄이기 위해 여러 번의 모의를 거쳐 입자의 평균 입경은 0.6m로 제안하고 시격은 1초 미만(평균 0.5초)로 설정하였다. 수문 및 발전방류는 해당댐의 1~2년 빈도 수준에 해당하는 $5,000m^3/s$ 이하의 유량을 기준으로 하여 모의를 수행하였다. 모의의 안정성을 확보한 이후에는 해당 댐지역의 하류영향을 고려한 문비제어를 반영한 다양한 방식의 수문운영 및 취수지점의 순간 수위 영향을 검토하였다. 그 결과로 본 모의에서는 특정한 수문의 운영 조건에서는 댐수위 계측지점과 인근 취수지점 간에도 0.2m 수준의 순간 수위차가 발생할 수 있음을 보였으며, 이는 경우에 따라 취수시설의 일시적 장애요소로 발생할 수 있음을 의미한다. 따라서, 현재의 취수구조물과 문비운영 특성에 따라 발생가능한 취수장애를 줄일 수 있는 운영조건의 탐색을 위해서 수치모의를 추가로 하였으며, 이 때 댐축 상류의 유속분포에 대한 추가 검토도 수행하였다. 다만, 댐에서 방류시 하류조건에 대한 검토는 추후 보강되어야 할 것으로 판단된다.

• Tuberculosis and Respiratory Diseases
• /
• v.66 no.1
• /
• pp.27-32
• /
• 2009

Background: The management of patients with lung cancer has improved recently, and many of them will require admission to the medical intensive care unit (MICU). The aim of this study was to examine the clinical characteristics and to identify risk factors for mortality in patients with lung cancer admitted to the MICU. Methods: We conducted retrospective analysis on 88 patients with lung cancer admitted to the MICU between April 2004 and March 2008. Results: Of the 88 patients (mean age, 66 years), 71 patients (80.7%) had non-small cell lung cancer and 17 patients (19.3%) had small cell lung cancer. Distant metastasis were present in 79 patients (89.8%). The main reasons for MICU admission were acute respiratory failure (77.3%), sepsis (11.4%), and central nervous system dysfunction (4.5%). Mechanical ventilation was used in 54 patients (61.4%). Acute Physiology and Chronic Health Evaluation (APACHE) II score, length of MICU stay, need for mechanical ventilation, source of MICU admission were correlated with MICU mortality. The type of lung cancer and metastasis were not predictive factors of death in MICU. Conclusion: Most common reason for ICU admission was acute respiratory failure. Mortality rate of lung cancer patients admitted to the MICU was 65.9%. APACHE II score, length of ICU stay, need for mechanical ventilation, source of MICU admission were predicted factors of death in the MICU.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2017.04a
• /
• pp.82-82
• /
• 2017

현대농업에서 잡초를 조기에 제거하지 못할 경우 작물의 성장에 장애를 초래하므로 제초작업은 매우 중요하다. 최근 친환경 고품질 농산물에 대한 소비자의 관심과 고품질 농산물에 대한 가격 차별화 등으로 제초제를 사용하지 않은 친환경 재배가 주목을 받고 있다. 제초제는 농작물에 따라 분류가 되어있어 종류마다 효과가 다르고 사용방법이 종류에 따라 어떻게 사용되는지 알기가 쉽지 않아 이에 따른 피해 또한 무시 할 수 없다. 현재 상용화되어 있는 제초기는 굴곡이 있는 고랑의 잡초를 효율적으로 제거하기 어려워 밭작물 제초작업에 사용하기 부적합하다. 밭작물 재배 기간에 행해지는 고랑의 제초작업은 평지보다 더 많은 힘이 필요하고 일반적인 제초기로는 좋은 결과를 얻기 어렵다. 또한 제초 작업시 농작물 피해와 멀칭 비닐을 손상시키는 문제가 발생 하고 있다. 따라서 밭작물에 효율적인 잡초를 제거하기 위해 굴곡이 있는 지형의 잡초를 제거하기 위한 제초기 개발이 반드시 필요하다. 밭작물용 제초기를 개발하기 위해 굴곡이 있는 고랑의 잡초 제거가 가능한 제초날의 형상 설계가 우선되어야 하며, 고랑의 잡초제거를 위한 제초날 형상설계를 하기 위해 우리나라 주요 밭작물 재배지의 이랑 넓이, 고랑 깊이 및 고랑 폭을 조사 분석하였다. 조사 작물 대상은 양파, 마늘, 무, 배추, 고추, 당근, 감자 총 7가지 작물을 대상으로 조사하였으며, 각 작물들의 이랑 넓이와 고랑 깊이 및 폭의 평균치를 구하여 제초날 설계에 적용하고자 하였다. 범위가 있는 수치는 높은 수치를 기준으로 계산하였으며 고랑의 평균 폭은 34.2cm이고, 고랑의 평균 깊이는 22.1cm가 나타났다. 잡초를 효과적으로 제거하기 위해 제초날의 형상은 고랑의 크기 및 형태에 맞게 원형으로 설계를 하여야 한다. 형상 설계는 밭작물 고랑 평균직경 및 평균높이를 고려하고, 제초작업시 제초날이 작물 및 멀칭비닐의 손상 하지 않도록 하기 위해 직경은 고랑 평균 폭의 75% 정도 치수로 형상을 설계하고, 제초날 깊이는 고랑의 굴곡형태을 고려할 때 제초날 반경의 70%정도로 설계하여 원형제초날 폭 250mm, 제초날 깊이 87.5mm로 설계해야 할 것으로 분석 되었다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.11
• /
• pp.1105-1110
• /
• 2012

The spine is one of the most important skeletal joints, and it strongly affects the health of the musculoskeletal system. A normal spine has an S-shape, and it is very important to maintain this shape. Recently, spinal diseases such as low back pain have increased rapidly, especially among the elderly. Some of these diseases are caused by congenital spinal disorders and sporting and accident injuries as well as by bad postures. Improper spinal postures could generate excessive disc pressure, which is related to degeneration and pain. Therefore, in this study, we investigated the three-dimensional kinematic parameters of the thoraco-lumbar joint in several bad postures using a motion capture analysis technique. Different bad postures created a significant amount of flexion/extension, side bending, and axial rotation angle compared with neutral postures. Further study is necessary to investigate the disc pressure and ligament force due to the increase in joint rotation from the bad postures.

• The Journal of the Korea Contents Association
• /
• v.17 no.1
• /
• pp.50-57
• /
• 2017

This study investigated the causes and problems of train operation impediments through the statistics analysis of 8 years'internal data of Daejeon Metropolitan Express Transit. By evaluating the risks regarding the system, equipment, and parts of high risk group, this study measured the Risk Index Severity, and applied the $5{\times}5$ Risk Assessment Matrix which is a method of risk management to calculate the scale of risk to analyze the safety level and allowance range. As a result, the car sector, the most serious risk, followed by machinery and equipment sector showed that the inherent risk. In particular, the door broken and the door rail signaling and control devices due to defects of the vehicle is high, but also the severity, and frequency are showing very frequent additional potential accidents. PSD also had defects in the machinery sector appeared to be the most dangerous of the PSD poor safety gates, it was found that the glass also involve the risk of mishandling and breakage of the PSD. This study intended to contribute to the transportation benefits through the safety and stable operation of Metropolitan Express Transit.