• 한국가시화정보학회지
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• 제21권1호
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• pp.119-126
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• 2023

Acquiring experimental data for PIV verification or machine learning training data is resource-demanding, leading to an increasing interest in synthetic particle images as simulation data. Conventional synthetic particle image generation algorithms do not follow physical laws, and the use of CFD is time-consuming and requires computing resources. In this study, we propose a new method for synthetic particle image generation, based on a Physics-Informed Neural Networks(PINN). The PINN is utilized to infer the flow fields, enabling the generation of synthetic particle images that follow physical laws with reduced computation time and have no constraints on spatial resolution compared to CFD. The proposed method is expected to contribute to the verification of PIV algorithms.

• 한국지능시스템학회논문지
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• 제25권6호
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• pp.571-577
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• 2015

본 논문은 운동기구에 장착할 수 있는 와이파이 모듈을 이용하여 운동시 운동량에 대한 데이터를 스마트기기에 전송할 수 있는 관리 모듈을 개발한다. 본 연구에서는 스틱(Stick)형 운동기구를 대상으로 운동기구에서 측정되는 운동량을 센서에서 측정한 후 무선통신을 통해 스마트 기기에 데이터를 보낸다. 스마트 기기에서는 사람별로 분류화된 데이터 목록에 운동량 데이터를 저장하여 추후 사용자에게 과거에 운동한 기록들을 보게 해준다. 제작된 앱(App)은 안드로이드와 iOS에서 모두 동작할 수 있도록 제작되었으며, 성능평가의 결과로서 내환경 시험 및 전자파 인증 시험을 외부전문기관의 챔버내에서 진행하여 성능을 만족함을 확인하였다. 개발된 운동량관리 모듈은 다양한 형태의 운동기구에 적용 가능하여 추후 많은 확장성을 갖는다.

• The Korean Journal of Physiology
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• 제3권2호
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• pp.1-7
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• 1969

Physiological analysis of swimming in 13 (age:16.3 years, freestyle swimming) and 15 (age:17.2 years, breast stroke swimming) high school boys through oxygen uptake and oxygen debt measurements were performed. The following results were obtained. 1. In freestyle swimming oxygen debt was greater and mechanical efficiency was lower in subjects with less speed. In beginner efficiency was only 1.35%, whereas, in a more skilled subject it ranged to 4.28%. The mean efficiency was 2.59%. 2. In freestyle swimming the speed-oxygen debt curve was convex to the speed axis and the curve shifted to the right the more the speed was greater. 3. Maximal oxygen uptake in breast stroke swimming was 2.51 l/min or 41.8 ml/kin/kg and was 79.3% of treadmill running. Maximal pulmonary ventilation in breast stroke swimming was 73.1 l/min and was 87% of treadmill running. Maximal ventilation equivalent was 2.89 liters. 4. In subjects with greater speed of breast stroke swimming maximal oxygen uptake and mechanical efficiency of swimming were greater. The mechanical efficiency of breast stroke swimming averaged 1.08% $(range:0.51{\sim}1.70%)$. The coefficient of correlation between speed and efficiency was r=.87.

• 대한물리치료과학회지
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• 제7권2호
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• pp.533-543
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• 2000

This study was designed to evaluate the analgesic effect of low power GaAsAl laser on the pain threshold of mechanical stimulation using different treatment points, acupuncture point (zusanli) and non-acupuncture points(back). Furthermore, we investigated the analgesic effect of low power GaAsAl laser using the different duration and intensity of laser in mechanical stimulation induced pain behavior. The results were summarized as follows: 1. The threshold of mechanical stimulation was significantly increased by GaAsAl laser stimulation into zusanli point after 15 and 30 min after laser stimulation(P<05). However, the laser stimulation into non-acupoint did not affect the pain threshold of mechanical stimulation. with dose dependent manner. 2. In order to investigate the analgesic effects of BV depending upon different intensities of laser stimulation, the experimental animals were divided into three groups: 3 mW treated group, 6 mW treated group and 10 mW treated group. The low power GaAsAl laser stimulation was applied into zusanli acupoint for 30 min with different intensity of laser stimulation. Six and ten mW of laser stimulation significantly increased the pain threshold of mechanical stimulation at 15 min after laser stimulation as compared to that of control group(P<.05). Moreover, the analgesic effect of 10 mW laser stimulation was maintained for 30 min after laser stimulation (P<.05). 3. Finally, we tested the analgesic effect of 10 mW laser stimulation using different duration such as 10 min, 30 min or 1 hr after application of mechanical stimulation. In 30 min treatment group, the pain threshold of mechanical stimulation was increased at 15min and 30min after laser stimulation(P<.05). However, laser stimulation for 60 min dramatically increased the pain threshold of mechanical stimulation at 0 min after laser stimulation and the analgesic effect of laser stimulation was observed until 1 hr after laser stimulation. In conclusion, these data apparently demonstrate that low power GaAsAl laser has analgesic effect on mechanical induced pain model in rats. In addition, the treated point, intensity and duration of laser stimulation should be concerned before clinical application for pain management purpose.

• 대한기계학회논문집A
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• 제39권1호
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• pp.45-53
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• 2015

세탁기의 용량이 커지면서 세탁 및 탈수 시의 세탁물에 의한 질량 불균형 문제가 심해지고 있으며, 이러한 문제를 해결하기 위하여 세탁기에서도 다양한 형태의 서스펜션이 장착되고 있다. 본 연구에서는 마찰 서스펜션에서 발생하는 힘을 측정한 뒤, 물리적인 수식으로 마찰 서스펜션의 비선형 특성을 모델링 하였다. 최소 자승 해(least squares solution)를 구해 파라미터들을 추정하고, 시험과 동일한 조건의 시뮬레이션을 실시하여 개발된 마찰 서스펜션 모델링의 타당성을 검증하였다.

• 한국기계가공학회지
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• 제19권10호
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• pp.59-67
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• 2020

Polycarbonate thermoplastic composite materials are anisotropic and exhibit physical properties in the longitudinal direction. Therefore, the physical properties depend on the type and direction of reinforcements. The thermal conductivity, electrical conductivity, and resin impregnation can be controlled by adding carbon nanotubes to polycarbonate resin. However, the carbon fiber used as a reinforcing material is expensive, interfacial adhesion issues occur, and simulation values are different from actual values, making it difficult to perform mathematical analysis. However, carbon nanotubes have advantages such as light weight, rigidity, impact resistance, and reduced number of parts compared to metals. Due to these advantages, it has been applied to various products to reduce weight, improve corrosion resistance, and increase impact durability. As the content of carbon nanotubes or carbon fibers increases, the mechanical properties and antistatic and electromagnetic shielding performance improve. It is expected that the amount of carbon nanotubes or carbon fibers can be optimized and applied to various industrial products.

• Journal of the Korean Wood Science and Technology
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• 제44권5호
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• pp.767-775
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• 2016

목재의 재질특성은 토양, 지형, 강우, 기후변화 등의 환경적 인자뿐만 아니라 임분 특성에 의해서도 바뀌게 된다. 지역 성림기원에 따라 종가시나무 목재의 물리 역학적 특성을 비교 검토하였다. 지역에 따른 비교분석은 전라남도와 제주도의 종가시나무 천연림을 대상으로 실시하였다. 지역에 따른 결과에서 제주지역은 전남지역에 비하여 높은 생장률을 나타내었으며 역학적 특성에서는 휨강도를 제외한 여러 역학적 특성에서 상관관계가 인정되었으나 실제 값으로 볼 때 큰 차이는 나타나지 않았다. 또한 성림기원에 따른 결과에서는 생장률 및 역학적 특성에서 특별한 차이가 나타나지 않았다.

• Journal of the Korean Wood Science and Technology
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• 제22권1호
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• pp.44-53
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• 1994

This research was carried out to investigate the effect of paper sludge addition on formaldehyde emission, and physical and mechanical properties of UF-particleboard. In order to investigate the effect of paper sludge addition to resin, particleboards were bonded with urea-formaldehyde resins containing 5, 10, 15% paper sludge powders of three types(A Type: -200 mesh, B Type: -100~+200 mesh. C Type: -50~+100 mesh), based on weight of resin solid. Also the effect of paper sludge addition to furnish was studied from particleboards fabricated with ratios of sludge to particle of 5:95, 10:90, 15:85 based on oven-dry weight. Tests were conducted on the manufactured particleboards to determine formaldehyde emission, bending properties, internal bond strength and thickness swelling. The obtained results were summarized as follows: The addition of paper sludge powder to resin yielded a higher pH of cured resin. Formaldehyde emission decreased with the increase of paper sludge powder addition to resin and paper sludge composition ratio to furnish. Particleboard bonded with urea-formaldehyde resin containing paper sludge powder and particleboard mixed with paper sludge have similar bending properties(MOR, MOE) and thickness swelling compared with control particleboard. Internal bond strength of particleboards treated with paper sludge were lower than that of control particleboard. The use of paper sludge as scavenger was achieved reduction of formaldehyde emission without depression of physical and mechanical properties of particleboard. Also the use of paper sludge was able to concluded that there is possibility of partial substitution of wood particle materials.

• Journal of the Korean Wood Science and Technology
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• 제44권2호
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• pp.172-183
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• 2016

Densification of the inner part of oil palm trunk (OPT) by the close system compression (CSC) method was performed in this study. The effects of the compression temperature and time on the anatomical, physical and mechanical properties of OPT were evaluated. The inner part of OPT with an initial average density of $0.3g/cm^3$ was used as samples. Oven-dried samples were immersed in water and vacuumed until fully saturated and then compressed by CSC at 120, 140, 160 or $180^{\circ}C$ for 10, 20, 30 or 40 min. The anatomical characteristics of transverse and radial sections before and after compression were compared by optical microscopy. The physical and mechanical properties, including the density, recovery of set (RS), modulus of elasticity (MOE), modulus of rupture (MOR), and compression parallel to grain were examined. It was observed that the anatomical characteristic of the inner part of OPT (i.e., vascular bundles, vessels, and parenchyma tissue) became flattened, fractured, and collapsed after compression by CSC. The RS decreased with increasing compression temperature and time. The lower RS indicated high dimensional stability. The physical and mechanical properties (i.e., density, MOR, MOE, and compressive strength) of the inner part of OPT increased with increasing compression temperature and time. Compression by the CSC method at $160^{\circ}C$ for 40 min was the optimum treatment.

• 한국전문물리치료학회지
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• 제22권3호
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• pp.50-60
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• 2015

The purpose of this study was to apply the joint mobilization technique to the level of segments with pain and to the level of segments with hypomobility respectively and compare the immediate effects of the joint mobilization technique on the pain, the active cervical range of motion (ROM), and treatment satisfaction of patients with acute mechanical neck pain. After the baseline assessment, forty-two patients were randomized into two groups: a painful group ($n_1=21$) that received joint mobilization at the most painful cervical spine level and a hypomobile group ($n_2=21$) that received joint mobilization at the most hypomobile cervical level. The patients received an intervention that applied unilateral posterior-anterior gliding for 5 minutes and two repetitions of 10 times of active extension motion with distraction. In the Wilcoxon signed-rank test, the painful group and the hypomobile group were improved significantly in all pain variables (p<.001), while the painful group was improved significantly in the active cervical flexion (p<.001), extension (p<.001), left side-bending (p<.01), right side-bending (p=.001), left rotation (p<.001), and right rotation (p<.001). The hypomobile group was significantly improved in active cervical flexion (p=.001), extension (p<.001), left side-bending (p<.05), right side-bending (p=.001), left rotation (p=.001), and right rotation (p<.01) after intervention. In the Mann-Whitney U test, there was no significant difference in any of the dependent variables after the intervention between the two groups, but the painful group was slightly superior to the hypomobile group in all variables except for the right lateral flexion ROM and treatment satisfaction. These outcomes suggest that the cervical joint mobilization may be applied to either the level of painful segments or the hypomobile segments for the treatment of patients with acute mechanical neck pain.