Field-free Spin-Orbit Torque Switching in Ferrimagnet/Non-magnet/Ferromagnet Trilayer Structures

Donghyeon Han,Namhee Kim,Jeongmok Kim,Jaimin Kang,Jong-Guk Choi,Dohyoung Kim,Soogil Lee,Byong-Guk Park 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Electrical manipulation of exchange bias in IrMn/NiFe heterostructures

Jaimin Kang,Jeongchun Ryu,Jong-Guk Choi,Taekhyeon Lee,Jaehyeon Park,Soogil Lee,Kab-Jin Kim,Byong-Guk Park 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1

Spin-orbit torque manipulation of exchange bias in IrMn/NiFe bilayer structures

Jaimin Kang,Jeongchun Ryu,Jong-Guk Choi,Taekhyeon Lee,Jaehyeon Park,Soogil Lee,Kab-Jin Kim,Byong-Guk Park 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

우리나라 가계 교통비 빈곤구조 분석

김범수(Kim, Beomsoo),이재민(Lee, Jaimin) 한국경제통상학회 2015 경제연구 Vol.33 No.3

본 연구에서는 우리나라 가계 교통비 지출구조를 분석하면선 빈곤구조에 포커스를 맞추어 실증분석을 시도하였다. 통계청 가계동향조사 연도별 자료와 빈곤지수 및 TIP 곡선을 이용하여 가계 교통비 지출 구조를 분석하였다. 그리고 교통비 지출 빈곤구조 비교를 위하여 전체 소비지출의 빈곤구조도 동일하게 분석하였으며 노인가구 및 1인 가구의 교통비 및 소비지출 빈곤구조도 분석하였다. 교통비 지출은 다른 소비지출에 비해 빈곤수준(incidence)과 정도(intensity)가 매우 높은 수준이며 노인 가구 및 1인 가구의 경우에도 빈곤수준과 정도가 높아서 저출산 및 고령화가 지속될 경우에 교통비 지출의 빈곤구조가 심화될 여지가 있었다. 실증분석에 기반하여 본 연구에서는 최저 교통비 법령화를 제안하였고 노인 및 1인 가구에 대한 교통비 지원정책을 필요성을 강조하였다. This study is to analyze the household transport expenditure in Korea and make empirical analyses on its poverty structure. In order to do that, we make use of household survey data of Korea Statistical Office and poverty index and Three ‘I’s of poverty(TIP) curve. To compare it with consumption structure, we analyze the poverty structure of household consumption in Korea, and investigate senior household and one-member household consumption and transport expenditure. The poverty level and intensity of transport expenditure are severe relative to those of consumption expenditure. Those of transport expenditure in senior and one-member households are more severe than those of consumption expenditure. We expect that low fertility and ageing makes poverty structure of transport expenditure deepen. We suggest that we should establish a code about minimum transport expenditure and that Korean government should supply support policies for senior and one-member households.

Field-free Spin-orbit Torque Switching in Co/Ti/CoGd Magnetic Trilayer Structures

Namhee Kim,Donghyeon Han,Jaimin Kang,Jong-Guk Choi,Soogil Lee,Byong-Guk Park 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.32 No.2

비모수적 방법론을 이용한 교통물류산업의 생산성 분석

이재민 ( Jaimin Lee ),이충기 ( Chung-ki Lee ),김희호 ( Heeho Kim ) 한국생산성학회 2017 生産性論集 Vol.31 No.2

In this study, the overall productivity change of the transportation logistics industry is analyzed using the non-parametric method, the first-order stochastic dominance, and the Kolmogorov-Smirnov test. In order to do that, we use “Transportation Survey 2004 and 2014” data provided by Korean Statistical Office. The analysis shows that per capita productivity has increased in the land and pipeline transportation, water transportation, and warehouse and transportation services industries. It is analyzed that productivity per person increases in the land passenger transportation industry and the road freight transportation industry, which are the subdivisions of the land and pipeline transportation industry. However, in the case of the road freight transportation industry, productivity per capita deteriorated at marginal enterprises, which led to suspicions that the various freight industries policies in the 2000s had intensified polarization. The maritime transport industry and the inland water transport and in-port transportation industry, which are sub-sectors of the water transport industry are also found to improve productivity per capita. In addition, the sub-sectors of warehouse and transportation service industries, such as the warehousing and the transportation-related services, are expected to improve productivity per capita in 2014 compared to 2004. Therefore, the per capita productivity of the warehouse and transportation-related service industries also increased in 2014 compared to 2004. As a result of this study, it is found that transportation companies` productivity increases with the overall change in the transportation logistics industry in Korea in the 2000s. However, it is difficult to grasp whether this change in productivity is caused by government policy changes or by the efforts of individual companies. This is also the limit of this study. Anyway, this study will be meaningful in that it has observed the productivity change of the overall transportation logistics industry including the 2000s and 2010s.

제주특별자치도의 주요 서비스 기업 특성 및 생산성 연구

이재민 ( Jaimin Lee ),김승규 ( Seung Gyu Kim ) 한국재정정책학회 2014 財政政策論集 Vol.16 No.1

본 연구에서는 제주특별자치도의 주요 서비스 산업인 도소매업, 음식점 및 숙박업, 부동산업 및 임대업, 교육 서비스업, 보건업 및 사회복지 서비스업, 예술, 스포츠, 여가 관련 서비스업에 대한 특성과 생산성을 분석하였다. 개별 서비스업 기업체 규모의 분포를 파악하기 위하여 정규분포, 로그 정규분포, Zip`s 분포에 대한 검증을 시도하였으며 종사자수에 따른 생산성 분석을 수행하였다. 또한 서비스 업체별 이질성이 업체별 생산성에 미치는 효과를 분석하였다. 분석결과에 따르면 개별 업체들의 종사자수는 대칭적인 정규분포를 따르지 않으며 생산성 역시 종사자수에 따라 상이하였다. 그리고 상용 근로자 비중이 클수록 부가가치가 높게 나타났으며 개인 사업체들의 부가가치가 낮게 산정되었다. In this study, we analyze the characteristics and productivity of the leading service industry in Jeju Special Self-Governing Province, such as wholesale and retail trade, restaurants and hospitality, real estate and leasing, educational services, healthcare services and social services, and arts, sports, leisure-related services. In order to identify the scale distribution of individual service companies, we test the normal distribution, lognormal distribution, Zipf`s distribution for the number of employees, and perform the productivity analysis of service industry companies according to them. In addition, we analyze the firm-specific heterogeneity effect on firm level productivity. According to the analysis results, individual firms` distributions based on the number of employees were not normally symmetric and their productivities were also different according to the number of employees. The larger the proportion of commercial workers for firms is, the higher their value-added are, and the value added of unincorporated businesses are low-value.

유형별 이익조정이 재무분석가의 장기예측치 발표에 미치는 차별적 영향

고재민(Goh Jaimin),김수인(Kim Sooin) 한국국제회계학회 2018 국제회계연구 Vol.0 No.81

일반적으로 회계학 연구에서 이익조정은 발생액을 이용해 장부상 이익을 직접 조정하는 발생액 이익조정과 경영 의사 결정을 변경하는 실물 이익조정으로 구분된다. 이 중 실물 이익조정은 발생액 이익조정에 비해 장기 경영성과에 미치는 부정적인 영향이 더 큰 것으로 알려져 있다. 재무분석가가 실물 이익조정의 장기간의 부정적 영향과 이로 인한 정보 불확실성을 이익 예측치 발표에 반영한다면, 발생액 이익조정에 비해 실물 이익조정이 커질수록 장기예측치 발표를 회피할 가능성이 있다. 본 연구는 2002년부터 2014년까지 유가증권시장 상장 기업을 대상으로 발생액 및 실물 이익조정의 규모가 커질수록 재무분석가가 장기예측을 발표하는 경향이 감소하는지를 로지스틱 회귀분석으로 검증하였다. 분석 결과, 발생액 이익조정은 재무분석가 장기예측치 발표에 유의한 영향을 미치지 않았으나, 실물 이익조정이 커질수록 재무분석가의 장기예측치 발표 경향은 유의하게 감소하였다. 또한, 실물 이익조정이 커질수록 재무분석가의 장기예측치는 부정적으로 나타났다. 더 나아가 실물이익조정이 재무분석가 장기예측치 발표를 위축시키는 경향은 재무분석가의 능력이 뛰어나거나 예측치 발표 대상이 되는 기업의 경영자 능력이 뛰어날수록 감소하였고, 이익조정이 의심되는 기업에 대해서는 그 경향이 증가하였다. 본 연구의 결과는 재무분석가들이 발생액 이익조정보다 실물 이익조정을 해석하는 데 더 어려움을 겪는다는 것을 시사한다. The purpose of this study is to examine whether the likelihood of financial analysts’ long-term forecast is differentially affected by real and accrual-based earnings management. Prior studies document that, compared to accrual-based earnings management, the negative effect of real earnings management on long-term business performance is remarkable. This aspect of real earnings management would lead analysts reluctant to provide long-term forecasts for firms engaged in large real earnings management. The results are as follows. First, the more real earnings management is performed, the less analysts announce long-term forecasts, however, we cannot find the significant relationship between accrual-based earnings management and the likelihood of long-term forecasts of analysts. Second, analysts provide pessimistic long-term forecasts for real earnings management. Our findings imply that financial analysts have more difficulties in figuring out the implication of real earnings management than accrual-based earnings management when producing long-term forecasts.

국제회계기준 도입이 재무분석가의 부담과 노력에 미치는 영향

김수인(Sooin Kim),고재민(Jaimin Goh),박주형(Ju Hyoung Park) 한국경영학회 2020 經營學硏究 Vol.49 No.3

We investigate the impact of International Financial Reporting Standards (IFRS) on financial analyst effort as well as the incremental effect of consolidation complexity on the changes of analyst effort after IFRS adoption. Further, we confirm the magnitude of impact from IFRS adoption decreases as the financial market has adapted to IFRS over years. First, we find that analyst effort in post-IFRS period is larger than in pre-IFRS. Further, the increase of analyst effort in post-IFRS period is strengthened as the number of consolidated subsidiaries more increases. Our findings imply that financial analysts concentrate their effort on forecasting consolidated earnings in post-IFRS period. Second, the increase of analyst effort is significantly larger in early times of IFRS than in more recent times, indicating financial analysts’ learning IFRS has improved. Overall, our results shed light on the negative influence from IFRS on information environment to which financial analysts face for earnings forecasts, but the negative impact has declined over years.

Reconfigurable spintronic physical unclonable functions based on spin-orbit torques in ferromagnet/nonmagnet/ferromagnet trilayer structures

Soogil Lee,Jaimin Kang,Jeong-Mok Kim,Taek-Hyeon Lee,Sungjun Lee,Donghyeon Han,Sanghwa Lee,Kab-Jin Kim,Byong-Guk Park 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1

Entering the era of Inter of Things (IOT), diverse smart devices generate and transfer enormous digital information. In this IOT environment, information security is becoming a critical issue because conventional software-based security technology is vulnerable to adversarial machine learning attacks. Thus, hardware-based security technology has been proposed to overcome this vulnerability, receiving much attention as an alternative. Especially, randomness of nature serves as an essential ingredient for the hardware-based security technology. For example, manufacturing processes of complementary-metal-oxide-semiconductor (CMOS) involves inevitable tolerances. Therefore, every electronic device is physically not identical despite the identical manufacturing processes. Those distinguishable device characteristics under the identical manufacturing process, so called “physical unclonable function (PUF)”, can potentially create non-identical output (response) under the identical input (challenge) generating unique identification of each electronic devices [1]. In this presentation, we demonstrate the spintronic PUF utilizing bottom-ferromagnet (FM)/nonmagnet/top-FM trilayer structures. Here, bottom and top FMs exhibit in-plane and perpendicular magnetic anisotropy, respectively. In these trilayer structures, field-free magnetization switching of top-FM is achieved by out-of-plane polarized spin current injection due to the interfacial spin precession mechanism, and the switching polarity is controlled by the in-plane magnetization direction of bottom-FM [2]. Under the identical demagnetization process of the bottom-FM, distinct magnetic domain distributions are formed on each identical wafer, consisting of a number of Hall-bar devices with random magnetization direction of bottom-FM along the demagnetization axis. These randomly distributed domains of bottom-FM on each wafer are electrically detected through the current-induced field-free spin-orbit torque switching polarity relies on the direction of bottom-FM. Therefore, these spintronic PUF wafers with unique pattern of domain distributions manifests itself as the unique electrical identification which can also be integrated into magnetic random access memory. Furthermore, we also discuss the reconfigurability and reliability of this spintronic PUF, providing great potential to hardware-based security applications because it is compatible with current CMOS technology.