• 패션비즈니스
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• 제6권3호
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• pp.41-51
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• 2002

The author of the paper investigated the changes of hairstyle along the developments in hairdressing industry in the 20th century. The development process of hairdressing industry was divided into four periods of introduction, origination, growth, and establishment. The corresponding changes of hairstyle were analyzed and the findings are as follows. 1. Hairstyle could be classified into such typical ones as traditional style, cut, bob, wave, permanent wave, up style, and hair coloring. 2. Fashion leaders affected the changes of hairstyle. 3. Whenever hairdressing appliances were introduced, new hairstyle was practiced as follows with the use of the appliances. (1) Introduction Period - Traditional Style : Chignon, pigtail ribbon $\rightarrow$ Variations were designed in hair length or split due to the limited availability of appliances. - Up Style : Pompadour, thick and up hair, encircling hair $\rightarrow$ Padding was used for sweep-up. (2) Origination Period - Bob Style : Women's first bob style. - Wave style : Wave with bob, close-cropped hair, up style $\rightarrow$ Iron, set, permanent devices were used. (3) Development Period - Wave Style : Wind wave, easily manageable wave $\rightarrow$ Blow dry, body permanent were used. (4) Establishment Period - Straight Style : Use of straight permanent. - Thick Wave Style : Development of various kinds of rod. - Hair Coloring : Advent of diverse fashion hair coloring, apart from the coloring of white hair, with the introduction of color TV. - Bob Style : Romantic bob style $^{\circ}\hat{E}$ Use of clippers and thinning scissors. Thus, the changes of hairstyle according to the development in hairdressing industry had close relationship with the improvement in hairdressing appliances.

• 전력전자학회논문지
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• 제4권4호
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• pp.318-324
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• 1999

본 논문에서는 영구자석형 선형 동기전동기의 제어특성을 개선시키기 위하여 유한요소 해석에 근거한 제어기법을 제시하였다. 제시한 제어기법에서는 이동자의 위치에 따라 통상의 제어기법에서의 전류분에 추가적인 보상분 전류가 추가되게 된다. 이동자의 위치 및 인가전류에 따른 영구자석형 선형 동기전동기의 추력리플 특성이 유한요소법을 이용하여 해석되었으며, 그 결과를 토대로하여 제어시의 코깅력에 의한 추력 리플을 보상하기 위한 전류값이 계산되었다. 속도제어시 종래의 제어법과 제시된 제어법에 따른 응답특성을 살펴 보았으며, 제시된 방법의 타당성을 검증하기 위하여 시험기를 제작, 실험하였다.

• 대한기계학회논문집A
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• 제33권9호
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• pp.938-948
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• 2009

In this paper, permanent magnets were used to remove magnetic sludge in the condenser of the power plant. To obtain the flow characteristics and magnetic information that are needed for determining a proper design of the magnetics sludge removal apparatus, numerical simulations were performed through the use of two commercial codes, ANSYS Workbench-Emag and CFX. Experiments were also performed on various kinds and sizes of magnets to obtain the magnetic information through a gauss meter. By analyzing the results of simulations and experiments, the minimum magnetic force that is able to remove the any size of the magnetic sludge in the condenser was calculated, and the design of the removal apparatus was confirmed. The test model which was confirmed by simulations and experiments was made. After testing, the test results were compared with those of numerical simulations and have good agreements.

• 전력전자학회논문지
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• 제21권2호
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• pp.134-143
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• 2016

This paper proposes a novel asymmetrical interior permanent magnet (IPM) brushless DC (BLDC) motor structure, which utilizes half-type permanent magnet (PM) configuration and has asymmetrical side gaps (slot next to the PMs) for reducing torque ripples. This structure uses 24% less volume of PMs than conventional IPM BLDC motor with a full set of magnets. The characteristics of the proposed motor are compared with three other half-type IPM BLDC motors through finite elements method (FEM) analysis, and the usefulness of the proposed motor was verified through experimental evaluation on prototypes of the conventional motor and proposed motor under various torque load conditions. This research obtained a high-performance IPM BLDC motor while decreasing manufacturing cost at the same time.

• Journal of Power Electronics
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• 제19권4호
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• pp.980-988
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• 2019

When compared with traditional power frequency generators, the frequency of a super high-speed permanent magnet generator (SHSPMG) is a lot higher. In order to study the influence of frequency on the electromagnetic field of SHSPMGs, a 60000rpm, 117kW SHSPMG was taken as a research object. The two-dimensional finite element model of the generator was established, and the two-dimensional transient field of the generator was simulated. In addition, a test platform of the generator was set up and tested. The reliability of the simulation was verified by comparing the experiment data with that of the simulation. Then the generator electromagnetic field under different frequencies was studied, and the influence mechanism of frequency on the generator electromagnetic field was revealed. The generator loss, voltage regulation rate, torque and torque ripple were analyzed under the rated active power load and different frequencies. The influences of frequency on the eddy current density, loss, voltage regulation rate and torque ripple of the generator were obtained. These conclusions can provide some reference for the design and optimization of SHSPMGs.

• Safety and Health at Work
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• 제14권3호
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• pp.295-302
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• 2023

Background: Fisheries and aquaculture are statistically acknowledged to be among the most dangerous occupations. Yet, industrial safety and health precautions against occupational accidents within the sector are not sufficiently implemented in many parts of the world. The present study aims to provide a quantified overview of work accident statistics in the Turkish fisheries and aquaculture industry. Methods: This article presents an overview of reported injuries and fatalities in the Turkish fisheries and aquaculture industries from 2006 to 2020. Incident, permanent incapacity, and fatality rates were calculated, and the difference between fisheries and aquaculture was statistically examined. Results: The overall incident, permanent incapacity, and fatality rates were 449.4, 4.7, and 5.7 per 100,000 worker years, respectively, over the 15-year period. With these fatality rates, fisheries and aquaculture are two of the industries with the highest fatality rates among comparable industries in Turkey. Incident rates in fisheries and aquaculture indicated that aquaculture work is more dangerous and risky. The data set includes 25 fatalities and 22 permanent incapacity cases over 15 years and shows an increase in fatality rates and occupational accidents in the last 8 years. Conclusion: present study showed that the quality of data and reporting in the Turkish fisheries and aquaculture industries including occupational illnesses, must be improved in order to be more preventative and to develop efficient safety management in the sector. Incentives for providing thorough data on occupational incidents must be enhanced to improve occupational safety awareness in Turkish fisheries and aquaculture.

• 한국측량학회지
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• 제29권3호
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• pp.237-247
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• 2011

우리나라의 GPS상시관측소는 1995년 국토지리정보원내에 최초로 설치된 이후, 2011년 현재 72개가 측량과 항법의 기준점으로 설치되어 활용되고 있다. GPS의 기준좌표계는 지심좌표계로써 그 중심은 1년에 약 1mm내외로 극히 작지만 끊임없이 움직이고 있기 때문에 특정 시간에 고정된 좌표계와 GPS데이터로써 그 좌표를 설정하고 있다. 한 국가 내에서 측량과 지도제작 목적으로 사용되는 GPS상시관측소는 상대적인 측량의 기준이기 때문에 국가적인 규약에 따라서 특정 시간대의 좌표계를 설정하여 사용하는 것이 혼란을 방지할 수 있다. 그러나 지심의 변화가 아닌 지각변동에 의한 GPS상시관측소간 기선의 상대적인 변화는 GPS상대측위의 정확도를 저하시키는 원인이 된다. 우리나라는 비교적 안정된 지각으로 구성되어 있다고 판단되어 왔기 때문에 지각변동에 따른 국가 기준점의 성과 갱신을 고려하지 않았다. 본 연구에서는 우리나라 GPS상시관측소 중 40개와 우리나라 주변의 국제 GPS상시관측소 5개를 선정하여 30개월간의 일별 GPS 데이터에 대하여 정밀기선해석을 실시하고, 전세계 130개 IGS GPS상시관측소망과 결합 조정함으로써 우리나라 GPS상시관측소의 연간 변동량을 계산하였다. 이로부터 우리나라 지각변동량의 특성을 분석하고 GPS상시관측소 사이의 상대적인 변동량을 계산하여 GPS상대측위의 기준점 역할수행을 위한 GPS상시관측소의 성과갱신 주기를 분석하고 정밀 GPS상대측위를 위한 한반도 지각변동모델은 개발하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 추계학술대회 논문집
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• pp.289-295
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• 2005

LMTT(Linear Motor-based Transfer Technology)는 항만 자동화를 위한 수평 이송 시스템이며, 셔틀카(shuttle car)와 격자구조의 레일에 부착된 스테이터 모듈(stator module)로 구성된 PMLSM(Permanent Magnetic Linear Synchronous Motor)에 의해 구동된다. 본 논문에서는 LMTT시스템에서 컨테이너 운반을 담당하는 셔틀카(shuttle car)를 구성하는 부품인 이동체(mover)의 경량화를 위하여 직교배열표 및 크리깅 방법을 이용하여 최적설계를 수행한다. 설계변수로는 가로빔, 세로빔, 휠빔의 두께를 제한조건 함수로는 안전율이 고려된 응력을 넘지 않도록 설정하였다. 목적함수로는 중량을 설정하였다. 본 연구에서 제시된 방법으로 구한 최적해는 크리깅 내삽법(Kriging interpolation)으로 알려진 DACE(Design and Analysis of Computer Experiments) 모델을 엑셀(Excel)로 수식화하고 구했으며, GENESIS를 이용하여 민감도기반 최적설계로 구해진 최적해와 비교 및 검토하였다.

• 전력전자학회논문지
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• 제21권5호
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• pp.418-426
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• 2016

This paper analyzes the effect of resistance error to the performance of sensorless drive system of surface-mounted permanent magnet synchronous machine (SMPMSM) based on the back-EMF observer. The analysis shows that the bandwidth of the entire sensorless drive system decreased in the low-speed region when using smaller resistance value than the actual one in the back-EMF observer. Even if the back-EMF observer invokes estimation error, the entire sensorless drive system does not make any steady-state position error. These characteristics may have positive effects such as extension of the low speed limit that goes further down in the sensorless drive. The validity of the analysis is verified by the experimental setup comprising the MG set.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.274-277
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• 2008

Pohang Wind Energy Research Center (PoWER-C) is developing a 3 MW Radial Flux Permanent Magnet (RFPM) Synchronous Generator for offshore Wind Energy Converter (WEC). The blade rotor rpm is 15.7 and the gear ratio is set to be 92.93. The nominal generator rpm at the rated load is about 1459. Baseline design with surface mounted PM magnets are completed. However, there is some concern about the excessive eddy current heating in the magnets. To alleviate this problem, another design with embedded magnet is going on. With embedded magnets, the generator length should be increased to compensate the increased flux leakage. But the field fluctuation in the magnets due to the slots are greatly reduced. This means less eddy currents and lower magnet operating temperature. In this report, engineering efforts for embedded rotor is presented.