• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.50-56
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• 2017

The IRR (internal rate of return) is often used by investors for the evaluation of engineering projects. Unfortunately, it is widely known that it has serial flaws. Also, External rate of returns (ERRs) such as ARR (Average Rate of Return) or MIRR (MIRR, Modified Internal Rate of Return) do not differentiate between the real investment and the expenditure. The PRR (Productive rate of return) is faithful to the conception of the return on investment. The PRR uses the effective investment instead of the initial investment. In this paper, we examined two cases of the engineering project. the one is a traditional engineering project with financing activity, another is the project with R&D. Although the IRR has only one value, it overestimates or underestimate profitabilities of Engineering Projects. The ARR and the MARR assume that a returned cash reinvest other projects or assets instead of the project currently executing. Thus they are only one value of a project's profitability, unlike the IRR. But the ARR does not classify into the effective investment and non-investment expenditure. It only accepts an initial expenditure as for an investment. The MIRR also fails to classify into the investment and the expenditure. It has an error of making a loss down as the investment. The IRR works as efficiently as a NPW (Net Present Worth). It clearly expresses a rate of return in respect of an investment in an engineering project with a loan. And it shows its ability in an engineering project with a R&D investment.

• Journal of the Korean Solar Energy Society
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• v.36 no.2
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• pp.19-29
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• 2016

Whilst there are growing interests in pursuing energy efficiency and zero-energy buildings in built environment, it is widely recognised that Building-Integrated Photovoltaic (BIPV) is one of the most promising and required technologies to achieve these goals in recent years. Although BIPV is a broadly utilized technique in variety of fields in built environments, it is required that generation of BIVP should be analysed and calculated by external specialists. The aim of this research is to focus on developing a new diagram for prediction of the pre-estimation model in early design stage to harness solar radiation data, PV types, slopes, azimuth and so forth. The results of this study show as follows: 1) We analysed 162 districts in a national level and the examined areas were categorised into five zones. The standard deviation of the results was 2.9 per cent; 2) The increased value of solar radiation on a vertical plane in five categorised zones was 42kWh/m3, and the result was similar to the average value of 43.8kWh/m3; and 3) The pre-estimation of diagram was developed based on the categorisation of zones and azimuth as well as the results of the developed diagram showed little difference compared to the previously utilised method. The suggested diagram in this paper will contribute to estimate BIPV without any external contribution to calculate the value. Even though the result of this study shows little difference, it is required to investigate a number of different variables such as BIPV types, modules, slope angle and so forth in order to develop an integrated pre-estimation diagram.

• Imaging Science in Dentistry
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• v.42 no.1
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• pp.19-24
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• 2012

Purpose : Field of view and voxel resolution of cone beam computed tomography (CBCT) might affect the diagnostic capability. This study was performed to compare between the standard and HiRes zoom modes in the diagnosis of external root resorption (ERR) using CBCT. Materials and Methods : Sixty three small cavities (0.25 mm depth and 0.5 mm diameter) were simulated on the buccal, lingual, and proximal surfaces at three different levels of 16 roots of teeth. After covering the root with nail varnish, the roots were inserted in the sockets and the model was placed in a water-containing lacuna. CBCT scans were taken in both standard and HiRes zoom modes using NewTom VG (QR srl Company, Verona, Italy). Then, an observer assessed the images to determine the presence or absence of the cavities. This process was repeated by increasing the size and depth of cavities to 0.5 mm depth and 1 mm diameter. Data were analyzed by McNemar test. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio in evaluation of the simulated cavities were calculated. Results : There was a significant difference between the two imaging modes in diagnosing the shallow cavities (p=0.02).The sensitivity of the standard zoom in detecting the shallow cavities was lower than that of the HiRes zoom. The likelihood ratio of the HiRes zoom was higher in the diagnosis of both cavity types. Conclusion : This study suggested that a smaller voxel size in the HiRes zoom mode of CBCT is preferred for diagnosis of ERR.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.60-61
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• 2003

Theoretical considerations on a giant magneto-impedance (GMI) effect in amorphous ribbons (i.e., thin films) have been made in terms of the expressions of effective permeability and impedance derived in the frame of classical electrodynamics and ferromagnetism. The dependence of GMI effect on the external do magnetic field (H$\_$ext/) and the frequency of alternating current are simulated and discussed in the knowledge of energy conversion consisting of the current energy loss, the ferromagnetic energy consumption, and the magnetic energy storage in the film. The obtained results are summarized as follow: (a) As frequency f< 20 ㎒, the real part of effective permeability (${\mu}$′) changes slightly. The peak of the ${\mu}$′curve always locates at H$\_$ext/=H$\_$ani/ - the anisotropy field. However, the peak value of ${\mu}$′ tends to increase with increasing frequency in the frequency range of 11-20 ㎒. (b) In the frequency range, f= 21-23 ㎒, a negative peak additionally appears. Meanwhile, both the positive and negative peak values rapidly increase with increasing frequency and their peak positions shift towards a high H$\_$ext/. (c) The positive peak value of ${\mu}$′ starts to decrease at f= 29 ㎒ and its negative peak does so at about 35 ㎒. Then, both peaks keep such a tendency and their peak positions move to high H$\_$ext/, as increasing frequency. (d) The dependence of the imaginary part of effective permeability (${\mu}$") on the external dc magnetic field and the frequency of the alternating field indicates that there is only one peak involved in ${\mu}$" for the whole frequency range. (e) The impedance vs. magnetic field curves at various frequencies show that there is a critical value of frequency around f= 18-19 ㎒ where the transition between two frequency regimes occurs; the one (low frequency) in which ${\mu}$′ predominantly contributes to the GMI effect and the other (high frequency) in which ${\mu}$" determines the GMI effect.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.183-188
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• 1997

A method for designing a broadband transducer was investigated experimentally. Control of the resonance frequency of a Piezoelectric circular transducer with two pairs of electrodes was achieved by varying the inductance of external coil connected across the terminal of one pair of electrodes of transducer. The conductance curves of transducer in water were obtained as a function of the inductance value in mH of the coil used in the tuning. As the tuning inductance is increased in value, the resonance frequency is reduced toward the fundamental frequency of 50 kHz. This interesting result suggest that it is possible to produce a continuously tunable transducer covering a frequency range between 61.3 kHz and 121.7 kHz by varying the inductance value of external coil from 2.7 mH to 15.0 mH. One of other problems in the design and construction of such broadband transducer is the transducer efficiency, but this will be the subject of our future work.

• Journal of the Korean housing association
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• v.26 no.3
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• pp.55-64
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• 2015

This study is conducted to understand the social value of Nakwon building, which has been instilled in the architecture of the building, through an analysis of formative elements unique to the center. The architectural characteristics of Nakwon building have been formed over a long period of time in relation with its surroundings and social change. Before looking into the formation of the center, this study investigates the street network planning of downtown. The street network was planned to expand in a north-south direction in order to accommodate a future increase of traffic volume as a result of industrialization and a population increase in downtown. This was manifested in expanding Samilro Street which passes through the lower part of Nakwon building, as well as in forming the architecture of the center. That is, the center has formed a symbiotic relationship with its surrounding areas, sharing space with them. The interior of the center seems to have an independent form while keeping a relationship with its external format, but it is seeking change internally in response to external change. Interior space has been departmentalized over time since its initial establishment, and the internal traffic has also been subdivided accordingly. This is attributable to the fact that social change in the neighboring areas affected the formation of Nakwon building, and that in turn contributed to forming the unique characteristics of the building. Nakwon building is one of the deteriorated buildings in downtown Seoul. However, it was built out of social need to share space within the city, and it has been changed according to social need for the 'distribution of space within the building.

• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1752-1757
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• 2017

The aim of this study is to evaluate the radioactivity levels and radiological impacts of representative black sand samples collected from different locations in the Rashid area, Egypt. These samples were prepared and then analyzed using the high-resolution gamma ray spectroscopy technique with a high-purity germanium detector. The activity concentration ($A_c$), minimum detectable activity, absorbed gamma dose rate, external hazard index ($H_{ex}$), annual effective dose rate equivalent, radium equivalent, as well as external and internal hazard index ($H_{ex}$ and $H_{in}$, respectively) were estimated based on the measured radionuclide concentration of the $^{238}U$($^{226}Ra$) and $^{232}Th$ decay chains and $^{40}K$. The activity concentrations of the $^{238}U$, $^{232}Th$ decay series and $^{40}K$ of these samples varied from $45.11{\pm}3.1Bq/kg$ to $252.38{\pm}34.3Bq/kg$, from $64.65{\pm}6.1Bq/kg$ to $579.84{\pm}53.1Bq/kg$, and from $403.36{\pm}20.8Bq/kg$ to $527.47{\pm}23.1Bq/kg$, respectively. The activity concentration of $^{232}Th$ in Sample 1 has the highest value compared to the other samples; this value is also higher than the worldwide mean range as reported by UNSCEAR 2000. The total absorbed gamma dose rate and the annual effective dose for these samples were found to vary from 81.19 nGy/h to 497.81 nGy/h and from $99.86{\mu}Sv/y$ to $612.31{\mu}Sv/y$, which are higher than the world average values of 59 nGy/h and $70{\mu}Sv/y$, respectively. The $H_{ex}$ values were also calculated to be 3.02, 0.47, 0.63, 0.87, 0.87, 0.51 and 0.91. It was found that the calculated value of $H_{ex}$ for Sample 1 is significantly higher than the international acceptable limit of <1. The results are tabulated, depicted, and discussed within national and international frameworks, levels, and approaches.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.125-134
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• 2009

The muscle strengths in various postures are used in our daily life with or without our recognition. Also, many works are still performed with strengths, although mechanization and automation have been fairly accomplished at the industry site. Since the late seventies, various body measurements have been conducted periodically in Korea, however, muscle strengths have not been measured actively. For this reason, the muscle strength data have been hardly accumulated. The aims of this study are to learn more about the physical strength of young-aged Koreans and to provide basic information for designing equipments, tools and facilities in the work site and daily life. The muscle strengths that are related to shoulder and upper limbs joints, which are used frequently, are measured in this study. Eighteen muscle strengths, from seven different movements such as elbow flexion, elbow extension, shoulder abduction(seated), shoulder adduction(seated), shoulder rotation(internal and external), lifting a tray, and turning a key(inward and outward) were measured. For every movement, the muscle strengths for both hands were measured. In each measurement, five seconds averaged value and peak value were collected. Comparing the average value, the strength of shoulder adduction was the strongest for male and female, while strength of turning a key inward with left hand was the weakest for male and female. Strengths of preferred hand in elbow extension, shoulder abduction, shoulder external rotation, lifting a tray, and turning a key were stronger than those of non-preferred hand for both male and female. Rohrer's index considerably had an effect on muscle strength. The results of this study can provide some basic information not only in designing the equipment and facilities in work site or daily life, but also in selection, training and management of workers.

• Journal of Convergence for Information Technology
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• v.12 no.5
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• pp.107-115
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• 2022

The purpose of this study is to identify the drivers of supply chain vulnerability and internal/external disruptive events and to verify the moderating effect of SCRM to mitigate negative disruption impacts. The analysis results of 182 SMEs are as follows. First, SC vulnerability proceeded from excessive efficiency. Second, the probability and severity of internal factors were higher than that of external factors. In particular, the priority of responding to risks arising from the supply chain process was higher than the value chain within the firm. Finally, the higher the level of risk management in the supply chain, the more positively the negative disruption impact was mitigated. This study is valuable in providing practical clues to the decision-making of a firm's managers and policymakers responding to supply chain risks.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.225-232
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• 1999

Construction case of PRD (Percussion Rotary Drill) pipe pile and matters to be attended in construction of PRD pile were reviewed. The compressive and uplifting static pile load tests for PRD piles were performed and, also, analysis by Pile Driving Analyzer was done. Based on these results, bearing components in each resisting part (that is: steel toe, external skin, and internal skin) were measured separately. The measured resisting force was compared to the value calculated by the estimated formula. The pile capacity was mobilized in steel toe area and the external skin friction and the internal friction were not produced. Thus, it could be considered that toe of PRD pile should be supported in hard bearing stratum (for example, the fresh soft rock).