• 한국전문물리치료학회지
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• 제30권3호
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• pp.174-183
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• 2023

Background: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS). Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs). Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954-0.971) and inter-day (ICC = 0.865-0.937) values, standard error of measurement (SEM) values (1.05°-2.04°), and minimal detectable change (MDC) values (2.92°-5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity. Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

• 마이크로전자및패키징학회지
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• 제24권3호
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• pp.77-81
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• 2017

Pulse electroplating of Ni-P alloy was studied to fulfill the material requirement to the advanced vertical probe tip in wafer probe card. The major concerns are for the electrical conductivity and yield strength. Plating parameters such as current density, duty cycle and solution components were examined to obtain the nanocrystal structure and proper percentage of phosphorus, leading to how to control the nanocrystal grain growth and precipitation of $Ni_3P$ after heat treatment. Among the parameters, the amount of phosphorus acid was the main factor affecting on the grain size and sheet resistance, and the amount of 0.1 gram was appropriate. Since hardness in Ni-P alloy is increased by as-plated nanocrystal structure plus precipitation of $Ni_3P$, the concentration of P less than 15 at% was better choice for the grain coarsening without minus in hardness value. The following heat treatment made grain growth and dispersion of precipitates adjustable to meet the target limit of resistance of $100m{\Omega}$ and hardness number of over 1000Hv. The Ni-P alloy will be a candidate for the substitute of the conventional probe tip material.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.574-578
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• 2005

본 연구에서는 유화법을 이용한 alginate 미세입자 제조에 있어서 적절한 alginate 농도와 가교제인 calcium chloride의 농도를 조사하였다. 유화법을 통해 calcium-alginate microsphere는 구형으로 제조되었으며 입자의 크기는 alginate와 가교제의 농도가 증가함에 따라 감소하는 경향을 보였다. 약물방출 경향은 alginate의 농도가 2%(w/v)일 때와 calcium chloride의 농도가 10%(w/v)일 때 가장 좋은 결과를 얻을 수 있었다.

• Structural Engineering and Mechanics
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• 제62권5호
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• pp.631-642
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• 2017

Accurate actuator tracking plays an important role in real-time hybrid simulation (RTHS) to ensure accurate and reliable experimental results. Frequency-domain evaluation index (FEI) interprets actuator tracking into amplitude and phase errors thus providing a promising tool for quantitative assessment of real-time hybrid simulation results. Previous applications of FEI successfully evaluated actuator tracking over the entire duration of the tests. In this study, FEI with moving window technique is explored to provide post-experiment localized actuator tracking assessment. Both moving window with and without overlap are investigated through computational simulations. The challenge is discussed for Fourier Transform to satisfy both time domain and frequency resolution for selected length of moving window. The required data window length for accuracy is shown to depend on the natural frequency and structural nonlinearity as well as the ground motion input for both moving windows with and without overlap. Moving window without overlap shows better computational efficiency and has potential for future online evaluation. Moving window with overlap however requires much more computational efforts and is more suitable for post-experiment evaluation. Existing RTHS data from Network Earthquake Engineering Simulation (NEES) is utilized to further demonstrate the effectiveness of the proposed approaches. It is demonstrated that with proper window size, FEI with moving window techniques enable accurate localized evaluation of actuator tracking for real-time hybrid simulation.

• 한국경영과학회지
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• 제42권2호
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• pp.49-61
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• 2017

The study on the efficiency analysis of Korean automobile parts companies is mostly based on the calculation of the size of output such as sales. However, the performance indicators such as sales, operating profit, and net profit are directly related to the cost structure, and this cost structure is affected by changes in the company's asset structure and capital structure. As a result, it is necessary that efficient capital procurement should be done at the same time to create efficient management performance through proper investment. In this study, we aim to measure the efficiency of asset and capital procurement compared to the sales figures, such as sales, generated by 33 primary suppliers who supply parts to Hyundai Kia Motors. For this purpose, this study proposed a DEA cross analysis model that can simultaneously measure efficiency in terms of input assets and capital procurement based on the same management performance when analyzing the efficiency of domestic auto parts companies.

• 대한안전경영과학회지
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• 제18권1호
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• pp.57-64
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• 2016

The leisure life pattern of people is changing to a familial and enthusiastic way that eventually develops the camping culture. Thus, the number of campers and the size of camping market have been dramatically increased due to significant expansion of camping people. However, many camp grounds and facilities are operating without a proper registration by government rules and regulations. In addition, many of electronic and gas equipment and tools are not used in a safe way and in a safety regulatory boundary. Therefore, campers at the camping ground is situated in a fire and safety hazard. In addition, there is limitation in rules and regulations associated with camping ground safety and fire. This study analyzed the fire and hazard guidelines and rules regulations of developed countries of campground and compared them to the current situation in South Korea. Therefore, this study is to develop a safety and fire hazard guidelines and rules and regulations related to camp ground operation, gas and electronic equipment operation and management. The study will eventually reduce the future fire and safety incidents in a campground in South Korea.

• 설비공학논문집
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• 제20권3호
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• pp.167-174
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• 2008

Cost related to building equipment accounts for about 85% of the life cycle cost of buildings. Therefore proper selection of air-conditioning system is important for reducing the overall cost of buildings. In this study, medium capacity EHP and GHP for air-conditioning a building with a floor area of 1,200 $m^2$ are compared economically. To consider all the factors of initial and operation costs effectively, an annual equal payment method is proposed. For the initial cost, cost of equipment, construction, installation, electric facility, financial subsidy and tax cut is considered. Cost of basic electricity, energy(electricity and gas), space charge, labor, insurance and repair is considered for the operation cost. Under the assumptions made in this study, overall cost of EHP is less than that of GHP, but this is not absolute and different outcome may result if different assumptions are made. This study is useful for those who are interested in choosing an air-conditioning system that costs less for mid-size buildings with simple calculations.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.155-156
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• 2012

In the modern age, as man's demand of energy is continuously grew, tidal becomes one of the sustainable energy sources that have been investigating thoroughly recently. Tidal turbine has proved high potential as a future power-generating device. To effectively capture tidal energy on site, a group of tidal turbines should be used and positioned in some formation with proper size and space so that energy can be absorbed from multiple point. Thus, the turbines together with the flow filed becomes a huge domain, a tidal farm. So, it becomes more convenient if a whole turbine farm is simulated by means of actuator discs since the time and cost for analysis can be reduced. This paper aims to evaluate the operating performance (power efficiency and energy restoration rate), mutual influence (for different longitudinal and lateral spaces), the influence of velocity profiles, turbulence intensity and the far wake characteristic of tidal turbines operating in farm formation. The results of this study help contributing to the present development of tidal turbine as the future potential energy conversion machinery.

• 식품보건융합연구
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• 제5권6호
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• pp.11-16
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• 2019

The construction environment has been declared as a hazard prone area due to high number of accident and death. The study aims to identify influential factors that contribute to poor safety practices and its consequences on construction workers in Cape Coast Metropolis. Seventy respondents were taken as the sample size for the study. Descriptive analysis was used to analyze the data obtained from the field. Findings show that poor site management, working without safety gadgets, failure to use their Personal Protective Equipment (PPE) and negligence of workers were the main causes of accidents on sites. Poor site management had the highest ranking among the seven variables. Effects of poor safety practices on building construction site and delays in work execution were due to injury of workers, extra cost due to payment of compensation to injured victims, not motivated due to injury of worker and declined reputation of firm. Management team should motivate workers for safe work done, provide adequate PPE for their workers on site and have documented health and safety policy on site. Site authorities and management team should be on site regularly to ensure proper safety practices on construction site.

• 대한소아치과학회지
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• 제34권1호
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• pp.169-178
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• 2007

혼합치열기에 있어서 가장 흔히 나타나는 부정교합의 한 유형으로 총생 문제를 들 수 있다. 총생은 그 심한 정도에 따라서 정상적인 치열 발육 과정에서 일시적으로 나타나는 경우도 있으며 치열공간과 치아 크기간의 부조화에 의해서 비정상적으로 나타나는 경우도 있다. 따라서 총생에 대한 관리를 적절하게 하기 위해서는 정상적인 치열 발육 과정에 대한 이해가 선행되어야 한다. 본 종설에서는 정상적인 치열 발육 과정 및 총생의 심한 정도나 위치에 따른 일반적인 접근 방법에 대하여 알아보고자 하였다. 영구치가 맹출되는 시기는 개인 마다 다를 뿐만 아니라 맹출 순서에 있어서도 개인적인 편차가 심하므로 총생에 대한 관리는 일반적인 지식뿐만 아니라 개개인의 특성에 적합한 방법이 고려되어야 한다.