Design and Analysis of a Permanent-Magnet-Assisted Switched Reluctance Motor

Hongsik Hwang,Jin Hur,Cheewoo Lee 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.6

A permanent-magnet-assisted switched reluctance motor (SRM) having small excitation poles, where phase coils are concentrically wound on the poles and thin permanent magnets are inserted inside the poles, is proposed in this paper. The insertion of permanent magnets into the stator excitation poles has a significant influence on positive torque improvement leading to a boost in efficiency. Three key design parameters such as the thickness of permanent magnets, space between two adjacent permanent magnets, and the width of stator excitation poles are determined during a design procedure in terms of the enhancement of positive torque. Step-by-step design modification and a comparison between the proposed permanent-magnet-assisted SRM and no-permanent-magnet SRM have been conducted by means of static torque comparison along with dynamic performance. The first prototype from steel laminations up to its physical assembly has been constructed.

Design and Analysis of a Permanent-Magnet-Assisted Switched Reluctance Motor

Hwang, Hongsik,Hur, Jin,Lee, Cheewoo The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.6

A permanent-magnet-assisted switched reluctance motor (SRM) having small excitation poles, where phase coils are concentrically wound on the poles and thin permanent magnets are inserted inside the poles, is proposed in this paper. The insertion of permanent magnets into the stator excitation poles has a significant influence on positive torque improvement leading to a boost in efficiency. Three key design parameters such as the thickness of permanent magnets, space between two adjacent permanent magnets, and the width of stator excitation poles are determined during a design procedure in terms of the enhancement of positive torque. Step-by-step design modification and a comparison between the proposed permanent-magnet-assisted SRM and no-permanent-magnet SRM have been conducted by means of static torque comparison along with dynamic performance. The first prototype from steel laminations up to its physical assembly has been constructed.

Design of Magnetic Shield for Hall-Effect Current Sensor Using Integrated Magnetic Concentrator

Hongsik Hwang,Junghyun Cho,Cheewoo Lee 한국조명·전기설비학회 2020 조명·전기설비학회논문지 Vol.34 No.3

This paper proposes a shield shape design for minimizing the integrated magnetic concentrator (IMC) hall current sensor shield. Inside flux density and outside magnetic field error rate aren’t satisfied with performance by reducing an initial U-shaped IMC hall current sensor shield’s width and height for an IMC hall current sensor minimization. In order to solve the problem, first, inside flux density is decreased by adding air gap in the shield. Second, outside magnetic field error rate is decreased by adding top shield. Finally, suitable shield shape for minimization is designed by adding top middle shield. The minimization design work is reduced the number of experiments by using the orthogonal array table and main effect analysis method, which are one of the methods of the experimental design method. The proposed model satisfied the design considerations, and the shield area is reduced by 83.7% from the initial model, proving that it was a suitable shield shape for minimization.

승강기 도어용 자속교번 영구자석 전동기의 토크 맥동 저감

황홍식(Hongsik Hwang),조정현(Jeonghyun Cho),이치우(Cheewoo Lee) 대한전기학회 2019 전기학회논문지 Vol.68 No.2

A flux-switching permanent magnet (FSPM) motor using ferrite magnet is proposed to replace a permanent magnet synchronous motor (PMSM) for elevator door applications. The prototype of an FSPM motor has been built up for experimental validation. Back-electromotive force (EMF) is estimated to prove that simulated results are correct and reliable. The efficiency of an FSPM motor has been verified to be comparable to that of a PMSM in spite of using ferrite magnet, but there is a disadvantage in torque ripple due to the interaction of harmonic components between back-EMF and magneto-motive force (MMF). However, most of researches on an FSPM motor have been focused on eliminating the harmonic components of back-EMF. In this paper, the design process of an FSPM motor based on winding function theory has been given to diminish torque ripple by considering the harmonic components of back-EMF and MMF along with cogging torque at the same time.

연자성 분말을 이용한 고속 스위치드 릴럭턴스 전동기 설계

황홍식(Hongsik Hwang),이치우(Cheewoo Lee) 대한전기학회 2015 대한전기학회 학술대회 논문집 Vol.2015 No.7

The construction of tandem dye-sensitized solar cells from chemically-derived nanoporous photoelectrodes

Choi, Hongsik,Hwang, Taehyun,Lee, Sangheon,Nam, Seunghoon,Kang, Joonhyeon,Lee, Byungho,Park, Byungwoo Elsevier 2015 Journal of Power Sources Vol.274 No.-

<P><B>Abstract</B></P> <P>A tandem dye-sensitized solar cell (tandem-DSSC) was synthesized on the basis of thin-film semiconductor electrodes. The nanoporous <I>p</I>-type NiO films were successfully obtained by simultaneous deposition of Al and Ni, followed by selective etching of Al and oxidation. Likewise, the <I>n</I>-type photoanode was made where Ag was etched in nitric acid after the initial formation of Ag/TiO<SUB>2</SUB> nanocomposites. Such dye-sensitized photoelectrodes were combined to construct a tandem solar cell which exhibited an enhanced open-circuit voltage. Also, the tandem devices were subjected to various light fluxes to correlate the experimental cell parameters (open-circuit voltage, short-circuit current, fill factor, recombination shunt resistance, etc.) with the ideal one-diode model. Interestingly, impedance spectra of the tandem cell was well matched with the parameters from each of the <I>n-</I>type or <I>p-</I>type DSSC, indicative of successfully-designed tandem structure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fabrication of tandem-DSSCs by simple sputtering deposition and selective etching. </LI> <LI> Parameters (<I>V</I> <SUB>oc</SUB>, <I>J</I> <SUB>sc</SUB>, <I>FF</I>, <I>R</I> <SUB>sh</SUB>, and <I>R</I> <SUB>sh</SUB> <SUP>recom</SUP>) fitted with an ideal one-diode model. </LI> <LI> Successfully-designed tandem construction confirmed by impedance analysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Study on Hydrocarbon Trap Based on Various Media to Reduce Evaporative Emission from Automotive Vehicles

Kyungho Hwang(황경호),Jian Hou(후건),Sungyul Kim(김성열),Hongsik Byun(변홍식) 한국고분자학회 2018 폴리머 Vol.42 No.4

본 논문에서는 자동차의 증발 가스를 효과적으로 감소시킬 수 있는 탄화수소(HC)-트랩을 제조하였다. HC-트랩은 분말화된 네 종류의 활성탄을 함유하는 각각의 수용액에 부직포를 침지시키는 방법으로 제조하였다. 제조된 HC-트랩은 주사 전자 현미경(SEM), porosimeter(기공크기 측정) 및 tensometor(기계적 특성)로 특성을 조사하였다. 또한 증발가스의 흡착성능을 측정하기 위하여 butane working capacity(BWC) 및 차량 증발 배출 시험을 실시하였다. 중간 공극이 높은 경우의 HC-트랩은 높은 BWC 및 낮은 차량 증발 배출량을 보여주었다. 또한 HEEL 안정화 실험에서 상대적으로 크기(5~11 nm)가 작은 중간공극들은 증발가스에 의해 쉽게 포화될 수 있음을 알 수 있었다. 결론적으로 제조된 HC-트랩은 차량 증발가스의 우수한 배출성능과 증발 배출량의 높은 감소를 보여 주었으며, 차량 전체 배출가스 중 18.4 mg의 감소를 나타냈다. This paper reports on the preparation of hydrocarbon (HC) trap, which can exhibit the capability to effectively reduce evaporative emission from automotive vehicles. The preparation of HC-trap was accomplished by a dipping method which involved the immersion of a nonwoven material in an aqueous solution containing powdered activated carbon. Four kinds of activated carbon are used for HC-trap preparation. HC-traps were then characterized by scanning electron microscopy (SEM), porosimeter (measurement of pore size ) and tensometer (mechanical properties). We conducted butane working capacity (BWC) and vehicle evaporative emission test to check adsorption performance of evaporative emission. Given the high mesopore volume, the HC-traps exhibited high BWC and low vehicle evaporative emissions. It was also revealed that relatively smaller pore size (5~11 nm) of mesopore could be easily saturated by evaporative emissions with HEEL stabilization. Finally, prepared HC-trap showed excellent performance of vehicle evaporative emission test and high reduction of evaporative emissions which showed 18.4 mg of reduction of total vehicle emissions.

미국정신의학회 "Internet Gaming Disorder" 진단기준에 따른 청소년의 인터넷게임중독률과 주요 증상에 관한 연구: 새로운 진단기준의 적용가능성 탐색을 중심으로

유홍식 ( Hongsik Yu ),황재 ( Jae Hwang ) 한국지역언론학회 2016 언론과학연구 Vol.16 No.1

이 연구는 미국정신의학회(American Psychiatric Association)가 제안한 9개인터넷게임중독 진단기준(하부요인)을 적용해 국내 고등학생의 인터넷게임중독 현황과 주요 증상을 탐색하였다. 아울러 인터넷게임중독이 대인관계 능력, 공격성, 생활만족도와 어떠한 관계를 가지는지 살펴보고자 하였다. 6개 시·도 거주 571명의 고등학생 게임이용자를 대상으로 실시된 설문조사의 내용을 분석한 결과, 이들고등학생의 인터넷게임중독률은 9.1%(고위험군 4.55%, 잠재적 위험군 4.55%)이었다. 남학생의 인터넷게임중독율은 12.0%로 여학생의 중독률 3.6%보다 높은 것으로 나타났다. 인터넷게임중독의 주요 증상은 ‘조절실패’, ‘지속적인 과도한 이용’, ‘부정적 기분의 모면’, ‘기만(은폐)’이었다. 이 4가지 주요 진단기준만을 적용할 경우, 고등학생의 인터넷게임중독률은 2.6%로 낮아졌다. 이는 ‘정신질환 진단 및 통계편람’ 5판(DSM-5)에서 제시된 인터넷게임중독의 분류방식, 즉 다중체계방식(polythetic classification system)에 대한 추가적 논의의 필요성을 제기한다. 인터넷게임중독은 게임이용량(r=.32), 공격성(r=.21)과 정적 상관관계, 생활만족도와는 낮은 부적 상관관계(r=-.11)를 보였다. 예상과는 달리 인터넷게임중독은 대인관계 능력의 감소와는 관련되지 않는 것으로 나타났다. 이와 같은 연구결과를 기반으로 향후 인터넷게임중독 조사와 연구를 위한 논의를 진행하였다. This study explored prevalence rates of Internet games among Korean high school students, and the major symptoms with the nine diagnostic criteria of ‘Internet Gaming Disorder’ proposed by the American Psychiatric Association. This present study also explored interrelationships between Internet gaming addiction and psychosocial variables. The sample for this study was composed of 571 high school student gamers. The results showed that prevalence rates were 9.1% (males: 12.0%, females: 3.6%). The prevalent symptoms were ‘unsuccessful attempts’(relapse), ‘continued excessive use’, ‘mood modification’, and ‘deception’(lie). ‘Loss of interest’ was the lowest prevalent symptom. When these four core diagnostic criteria were applied, prevalence rates were dropped to 2.6%. This study also found that Internet gaming addiction is a gendered-phenomenon. Nearly 90% of Internet gaming addiction were males. Internet gaming addiction shows that positive corre-lation with game usage (r=.32) and aggression (r=.21), and negative correlation(r=-.11) with life satisfaction. Unexpectedly, Internet gaming addiction had no interrelationships with social competences such as ‘cognitive empathy’ and ‘interpersonal conflict management’.

Analysis and Design of a Double-Stator Flux-Switching Permanent Magnet Machine Using Ferrite Magnet in Hybrid Electric Vehicles

Kim, Dongjae,Hwang, Hongsik,Bae, Sungwoo,Lee, Cheewoo IEEE 2016 IEEE transactions on magnetics Vol.52 No.7

<P>A double-stator flux-switching permanent magnet (DS-FSPM) machine using ferrite is proposed to replace an interior permanent magnet synchronous motor (IPMSM) on hybrid electric vehicles. A conventional FSPM machine is designed, and its torque characteristic is analyzed by a frozen permeability method. It is verified that magnetic saturation causes the reduction of flux linkage generated by PM and leads to the deterioration of electromagnetic torque. A DS-FSPM machine is effective for magnetic saturation because of its unique structure and makes the improvement of efficiency and power density. The proposed DS-FSPM machine achieves distinct performance enhancement compared with an IPMSM, even by utilizing ferrite PM.</P>

Characteristics of Energy Harvesting in Flywheel Energy Storage System Based on Efficiency Map

Jeonghyun Cho,Hongsik Hwang,Gwansoo Park,Cheewoo Lee Korean Magnetics Society 2018 Journal of Magnetics Vol.23 No.4

In this paper, the characteristics of energy discharge in a flywheel energy storage system (FESS) are analyzed according to load condition mapped in the efficiency of a generator. As time goes by, the electromotive force (EMF) of a generator decreases in an FESS as a power source, but output power is maintained by boosting the generator voltage in a bidirectional power converter (BPC). Using the principle of operation of a boost converter, the variation of voltage gain in a BPC is investigated under the condition of load change, and current is compensated for the reduction of back EMF in a generator as its speed goes down. The loss of the FESS is separated into that of its generator, bearings, and BPC through experimental evaluation, and it has been verified that the generator plays a significant role in the efficiency of the FESS.