• 대한물리의학회지
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• 제10권2호
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• pp.89-94
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• 2015

PURPOSE: The aim of this study was to determine the effect of device considering Mckenzie type for the subjects with forward head posture (FHP). METHODS: The subjects were 35 patients with FHP (mean age was $23.7{\pm}2.8$ years; mean height; $172.1{\pm}11.7$, mean weight; $65.8{\pm}13.9$, mean NDI(Neck Disability Index; $3.7{\pm}3.2$, mean FHP; $6.7{\pm}2.2$). We measured the posture with the Body style S-8.0(LU Commerce, South Korea) to evaluate the FHP. We collected the surface EMG(Myosystem 1400, Noraxon, USA) data to quantify changes in normalized activation levels of muscles in SternoCleidoMastoid muscle(SCM), Scalenus Anterior(SA), Trapezius upper fiber(TU) and Splenius Cervicis(SC), during the subjects were instructed to glide their head into a "chin-in" position for a retraction without and with device. RESULTS: The condition with device significantly decreased the %RVC of SA($90.84{\pm}40.54$), SCM($74.98{\pm}43.65$) and TU($67.60{\pm}47.83$) compared to the condition without device(SA;$100.39{\pm}56.32$, SCM;$119.03{\pm}109.26$, Trapezius;$80.55{\pm}39.27$). But the %RVC of capitis($65.87{\pm}47.83$) with device was increased($70.82{\pm}52.78$). There was significant difference in the %RVC between SCM and Trapezius muscle in two conditions. CONCLUSION: New device for FHP reduces the EMG activities of the TU, SCM and SA muscle. We have to develop the function of feedback to facilitate the motion in the future.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.641-649
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• 2021

Fuel oil consumption (FOC) must be minimized to determine the economic route of a ship; hence, the ship power must be predicted prior to route planning. For this purpose, a numerical method using test results of a model has been widely used. However, predicting ship power using this method is challenging owing to the uncertainty of the model test. An onboard test should be conducted to solve this problem; however, it requires considerable resources and time. Therefore, in this study, a deep feed-forward neural network (DFN) is used to predict ship power using deep learning methods that involve data pattern recognition. To use data in the DFN, the input data and a label (output of prediction) should be configured. In this study, the input data are configured using ocean environmental data (wave height, wave period, wave direction, wind speed, wind direction, and sea surface temperature) and the ship's operational data (draft, speed, and heading). The ship power is selected as the label. In addition, various treatments have been used to improve the prediction accuracy. First, ocean environmental data related to wind and waves are preprocessed using values relative to the ship's velocity. Second, the structure of the DFN is changed based on the characteristics of the input data. Third, the prediction accuracy is analyzed using a combination comprising five hyperparameters (number of hidden layers, number of hidden nodes, learning rate, dropout, and gradient optimizer). Finally, k-means clustering is performed to analyze the effect of the sea state and ship operational status by categorizing it into several models. The performances of various prediction models are compared and analyzed using the DFN in this study.

• 한국전문물리치료학회지
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• 제30권1호
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• pp.23-31
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• 2023

Background: Several factors contribute to shoulder pain, including abnormal neck posture, repeated use of the upper limbs, work involving raising the upper limbs above the head, and the effects of vibration. However, previous study has reported that constant vibration exposure could impact improvement of the stability on joints related with muscle recruitment and activation. For this difference reason, we need to verify for the complex study of relationship with repetitive upper limb movements, poor head posture, and constant vibration exposure. Objects: Our study was made to investigate the influence of vibration exposure on the shoulder muscle activity during forward-head and over-head tasks with isometric shoulder flexion. Methods: In a total of 22 healthy subjects, surface electromyography (EMG) data were collected from shoulder muscles (upper/lower trapezius, serratus anterior, and lumbar erector spinae) on tasks (neutral-head task [NHT], forward-head task [FHT], and over-head task [OHT]) with and without vibration exposure. Results: In all tasks, the EMG data of the upper trapezius and serratus anterior significantly increased with vibration exposure (p < 0.05). Furthermore, the EMG data of the lumbar erector spinae significantly increased with vibration exposure in the NHT and FHT (p < 0.05). Conclusion: We suggest that continuous vibration exposure during the use of hand-held tools in the tasks could be associated with harmful effects in the workplace. Lastly, we clinically need to examine the guidelines regarding the optimal posture and vibration exposure.

• 한국기계가공학회지
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• 제16권2호
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• pp.135-141
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• 2017

An experimental study of micro blasting for a rotating aluminum rod was conducted through the statistical analysis of ANOVA to obtain the effect of blasting conditions. The rotating equipment was designed and constructed with forward and backward moving for helical blasting, but rotation was used in this study. The blasting condition factors were the type of abrasive particle, nozzle diameter, pressure, standoff distance, injection time, etc. The width of the surface, the maximum depth of the sprayed surface, and ANOVA were analyzed by statistical analysis. The results showed that the contributions of the main factors were pressure, nozzle diameter, and injection particle.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.40-42
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• 2003

The aim of this paper is to illustrate which factors influence the martensite grain fineness made by subsequently surface carburizing of extruded component. The effects of surface decarburizing by annealing, residual stress, initial microstructure and crystal oriental made by forward extrusion were taken into account. The available evidence suggests that the residual stress inside crystal or the crystal orientation is the main factor that results coarse martensite while cold extruded component was treated by carburizing.

• 제어로봇시스템학회논문지
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• 제18권11호
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• pp.1051-1058
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• 2012

The unified lateral control algorithm for automatic valet parking for various types of vehicles is presented and its feasibility is shown experimentally via field tests for the given parking scenario. First, a trajectory generation algorithm for forward driving and backward multi-step parking maneuvers is developed. Then, with consideration of different types of vehicles and operating conditions, a kinematic vehicle model is used and validated using field test data. Using the nonlinear vehicle model, the lateral controller is designed based on dynamic surface control. Finally the proposed lateral control law is validated via hardware-in-the-loop simulations for different types of vehicles and experimentally using a test vehicle through field tests.

• 한국군사과학기술학회지
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• 제17권3호
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• pp.336-341
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• 2014

When using a higher-order modulation scheme, there are variations in bit-reliability depending on the bit position in a modulation symbol. Variations of bit-reliability in the codeword block lower the decoding performance. Also, the decoding performance increases as the sum of the bit-reliabilities in the codeword block increases. This paper presents a novel hybrid automatic repeat request scheme that increases the sum of the reliabilities of the transmitted bits by lowering the modulation order, and decreases the variations of bit-reliability in the codeword block by preferentially retransmitting bits with low reliability. The proposed scheme outperforms the constellation rearrangement scheme. Furthermore, the proposed scheme also provides a good solution in cases where the size of the retransmission block is smaller than the size of the initial transmission block.

• 한국전기전자재료학회논문지
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• 제15권10호
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• pp.844-850
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• 2002

Linearly graded profiles on the field area oxide are frequently used in power integrated circuits to reduce the surface electric field when power devices are operated in forward or reverse blocking modes. It is shown here that tapered windows can be made using the difference of etch rates between the bottom and the top layer of TEOS film. Annealed TEOS films are etched at a lower rate than the TEOS film without annealing Process. The fast etching layer results in window walls having slopes in the range of 25$^{\circ}$∼ 80$^{\circ}$ with respect to the wafer surface. Taper etching technique by annealing the TEOS film applies to high voltage LDMOS, which is compatible with CMOS process, due to the minimum changes in both of design rules and thermal budget.

• 대한전자공학회논문지SD
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• 제41권7호
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• pp.37-41
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• 2004

We have formulated an empirical analytic model for the static characteristics of implanted vertical-cavity surface-emitting lasers (VCSELs). Specifically, we have derived analytic formulas for the threshold current, slope efficiency, dynamic resistance, and the output power and forward voltage at the operation current of 12 ㎃ in terms of the implant and metal-aperture radii by fitting the measured results. The radii of the metal aperture and implant mask of the 850 nm VCSELs range from 4 to 12.5 ${\mu}{\textrm}{m}$ and 7 to 17.5 ${\mu}{\textrm}{m}$ respectively. The model shows the way of tailoring the VCSEL characteristics by changing the mask dimensions only.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 추계 학술대회논문집
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• pp.43-48
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• 1995

A numerical computation is carried out to analyse characteristics of flow fields around Air Supported Ships having arbitrary form. The computations are performed in a rectangular grid system with MAC(Marker And Cell) method. The governing equations are represented in a Finite Difference form by forward differencing in time and centered differencing in space except for convection terms. For validation of this numerical analysis method, the computation of flow fields around Catamaran and ACV(Air Cushion Vehicle) with pressure distribution on free surface are done, and that around Surface Effect Ship is also carried out. The results of the computations are compared with the those of existed numerical computation and experimental results with the same condition.