• International Journal of High-Rise Buildings
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• v.6 no.4
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• pp.297-300
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• 2017

Employers are realizing that workplaces have an immense impact on productivity. And, because people typically represent about 90% of a company's costs, even a slight improvement in productivity hits the bottom-line in a very big way. The focus is shifting away from saving money by reducing space needs or cutting energy requirements, and moving toward making the workplace friendlier and healthier. What is a healthy workplace, exactly? The answer should be clear by now. Mountains of research have expounded on this very topic, and then news outlets cover the latest discoveres ad infinitum. The problem is, research is rather dense, while the news isn't comprehensive. Office managers trying to improve workplace wellness want neither a 55-page report nor a half dozen articles to convince their landlord that their space can do better. Recognizing this gap, Harvard researchers have released a concise-yet-complete list of healthy building features. Here, we're sharing these nine features with a few insights of our own on the value of being healthy and productive. Find out: ${\bullet}$ What makes a healthy building and why is it so important ${\bullet}$ How to improve the health of your own office ${\bullet}$ What happens for your people and your bottom line when you make health a priority.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.4
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• pp.153-161
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• 2008

신뢰성 평가 시험은 종종 성능 평가에 장기간의 시간이 요구되며, 전체 생산비용까지 증가시키는 문제점을 안고 있다 스트레스를 이용한 가속수명시험은 제품의 신뢰성 고장과 밀접한 관련이 있는 고장 메커니즘의 촉진을 통해 고장에 이르는 기간을 단축함으로써 신뢰성 평가의 효율성을 도모할 수 있다. 본 연구에서는 이러한 스트레스 가속 시험에 빈도가속(Usage-Rate Acceleration) 또는 판정가속(Tightening Critical-Values) 등을 결합하여 한층 높은 가속효과를 도모하는 방법을 제안하고, 국내에서 생산되고 있는 2차 전지 제품에 대한 실제 시험 사례분석을 통해 결합된 가속방법의 효과를 실증적으로 보여주고 있다.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.170-175
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• 2003

A control algorithm is developed for highly efficient operation of auxiliary power unit (APU) that consists of a diesel engine and a directly coupled induction generator in series hybrid electric Bus (SHEB). In a series hybrid configuration the APU supplies the electric power needed for maintaining the state of charge (SOC) of the battery unit in various conditions of vehicle operation. As the rotational speed of generator does not depend on the vehicle speed, an optimized operation of engine-generator unit based on the efficiency map of each component can be achieved. The output torque of diesel engine can be controlled by the amount of fuel injection, and the power converted from mechanical to electrical energy can be adjusted by generate control unit (GCU) using the decoupling vector control of torque and flux. As for the given reference of the generating power, the multiply of speed and torque, many combinations of operating speed and torque are possible. The algorithm decides the new operating point based on the engine efficiency map and generator characteristic curve. During the transition of operating points, the speed controller saturation is avoided using variable limit and filtering of generator torque reference. A test rig and SHEB consist of a 1.5L diesel engine and a 30kw induction generator are constructed by Hyundai Motor Company.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.5-13
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• 2015

The aim of this study is to investigate the feasibility of a new type of casing for the inline Francis hydro turbine. Comparing with the traditional turbine with spiral casing, this turbine is unique for its flow passage shape at the first stage of flow to the turbine, very similar to a pipe, called inline casing. Before the commercialization of this new type of casing, a global investigation of the inline casing must be conducted. Preserving the structural characteristics of simple, compact-size and convenient for manufacture, different shapes of the belt passage, vertical corner and stay vanes are applied to investigate the influence of flow passage shape on the turbine performance. Stable and relatively high efficiency is achieved regardless of flow passage shape difference proving the feasibility of the inline casing used in a hydro turbine.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.898-904
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• 2009

The objective of the present study lies in constructing web-based GIS system providing broad range of information applicable for power/telecommunications distribution facilities through cable. Nowadays, Korea is renowned forits faste sttele communications network across the nation enjoyable for being a test-runbed by worldwide contents providers. It is not too much to say that the trend is caused by the fact that Korea utilizes the cobweb-like power transmission cables applicable for the nationwide telecommunications networking. In particular, the trend has been all the more encouraged by the governmental drive to expedite the telecommunication network by way of the established power transmission facilities deemed as publicutility. Nevertheless, few can deny that the overexcessive competition among telecommunication service providers increasingly gives rise to unauthorized, arbitrary facilitation of distribution devices, which becomes much burden in operating the normal power/telecommunications distribution facilities by a power-generating company. In this regard, the study, to cope with such problems, attempts to develop a web GIS-based information management system compatible with NDIS(New Distribution Information System), a distribution facility management system now under operation by KEPCO, making advantage of GE Energy's SIAS(Smallworld Internet Application) technology. The model provided by this study is expected to get closer into effective operation of distribution facilities along with better sharing of information among conventional telecommunications operators, while getting rid of infringed facilitation cases

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.38-50
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• 2018

Spatio-temporal load forecasting (STLF) is a foundation for building the prediction-based power map, which could be a useful tool for the visualization and tendency assessment of urban energy application. Constructing one point-forecasting model for each electricity cell in the geographic space is possible; however, it is unadvisable and insufficient, considering the aggregation features of electricity cells and uncertainties in input variables. This paper presents a new STLF method, with a data-driven framework consisting of 3 subroutines: multi-level clustering of cells considering their aggregation features, load regression for each category of cells based on SLS-SVRNs (sparse least squares support vector regression networks), and interval forecasting of spatio-temporal load with sampled blind number. Take some area in Pudong, Shanghai as the region of study. Results of multi-level clustering show that electricity cells in the same category are clustered in geographic space to some extent, which reveals the spatial aggregation feature of cells. For cellular load regression, a comparison has been made with 3 other forecasting methods, indicating the higher accuracy of the proposed method in point-forecasting of spatio-temporal load. Furthermore, results of interval load forecasting demonstrate that the proposed prediction-interval construction method can effectively convey the uncertainties in input variables.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.1
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• pp.29-37
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• 2007

In this study, transmission and reflection of multi-directional random waves propagating over impermeable submerged breakwaters are calculated by using eigenfunction expansion method. A series of mutiderectional random waves is generated by using the Bretschneider-Mitsuyasu frequency and Mitsuyasu type directional spectrum. Strong reflection is occurred at the Bragg reflection condition of the peak frequency. If the row of breakwaters is fixed at 3 and the relative height of breakwater is fixed at 0.6, more than 25% of incident wave energy is reflected to offshore. It is also found that the reflection of directionally spreading random waves increases as the maximum spreading parameter $s_{max}$ increases.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1455-1460
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• 2014

Wind turbine generators were designed on general regulations of wind condition. At real situations, it could be different from the design conditions. There are many control methods and definitions of transient region, because an efficient wind turbine generator control logic is the important matter in generator performance and annual energy production at real conditions. In this document, the power generation sensitivity for wind speed and turbulence intensities was defined to know the sensitive transient region. Wind conditions are applied for the ranges of 7~10m/s mean wind speed and 14~20% turbulence intensity. The sensibility of HR-D86 wind generator was increased in transient region(8~10m/s) on power curve diagram through a torque control to a pitch control. And then GH-bladed simulations was performed for performance analysis of the torque mode switching in transient region on 2MW direct drive wind generator(HR-D86) which is designed IEC class II for onshore. Through the sensitivity and performance analysis, the sensitivity for real wind condition could be the performance index for an wind generator. And the torque mode switching in transient region can increase the mean power generation on HR-D86 wind turbine generator.

• Journal of Korea Water Resources Association
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• v.38 no.6 s.155
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• pp.429-438
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• 2005

In this study, a couple of ordinary differential equations which can describe random waves are derived from the Boussinesq equations. Incident random waves are generated by using the TMA(TEXEL storm, MARSEN, ARSLOE) shallow-water spectrum. The governing equations are integrated with the 4-th order Runge-Kutta method. By using newly derived wave equations, nonlinear energy interaction of propagating waves in constant depth is studied. The characteristics of random waves propagate over a sinusoidally varying topography lying on a sloping beach are also investigated numerically. Transmission and reflection of random waves are considerably affected by nonlinearity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.237-243
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• 1996

Current low head and small scale hydroturbines have limitations in the minimum required head and flow rate for efficient operation. This study attempts to develop a new concept hydroturbine which is expected to run efficiently even in very low head and small flow rate, so that the limitations on the conventional small scale hydropower could be alleviated and competition with other alternative energy sources in the economic respect could be attained. A small scale catapillar track- hydroturbine was fabricated and the performance test was carried out in a water tunnel over the head range of H = 0.8 m ~ 1.26 m. The peak turbine efficiency was 41.3% at the speed ratio of 0.6, and the turbine loss was mostly due to the friction at the chain drive used for power transmission from the runner to the shafts. This type of turbine is expected to become competitive when some improvement in the power transmission mechanism is made.