준안정상 기반의 질화철계 영구자석소재 제조연구동향

김경민,이정구,김경태,백연경,Kim, Kyung Min,Lee, Jung-Goo,Kim, Kyung Tae,Baek, Youn-Kyoung 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.2

Rare earth magnets are the strongest type of permanent magnets and are integral to the high tech industry, particularly in clean energies, such as electric vehicle motors and wind turbine generators. However, the cost of rare earth materials and the imbalance in supply and demand still remain big problems to solve for permanent magnet related industries. Thus, a magnet with abundant elements and moderate magnetic performance is required to replace rare-earth magnets. Recently, $a^{{\prime}{\prime}}-Fe_{16}N_2$ has attracted considerable attention as a promising candidate for next-generation non-rare-earth permanent magnets due to its gigantic magnetization (3.23 T). Also, metastable $a^{{\prime}{\prime}}-Fe_{16}N_2$ exhibits high tetragonality (c/a = 1.1) by interstitial introduction of N atoms, leading to a high magnetocrystalline anisotropy constant ($K_1=1.0MJ/m^3$). In addition, Fe has a large amount of reserves on the Earth compared to other magnetic materials, leading to low cost of raw materials and manufacturing for industrial production. In this paper, we review the synthetic methods of metastable $a^{{\prime}{\prime}}-Fe_{16}N_2$ with film, powder and bulk form and discuss the approaches to enhance magnetocrystalline anisotropy of $a^{{\prime}{\prime}}-Fe_{16}N_2$. Future research prospects are also offered with patent trends observed thus far.

연구 논문 : 전기화학적 마이크로머시닝 기술을 이용한 균일한 니오븀 표면 에칭 연구

김경민 ( Kyung Min Kim ),유현석 ( Hyeon Seok Yoo ),박지영 ( Ji Young Park ),신소운 ( So Woon Shin ),최진섭 ( Jin Sub Choi ) 한국공업화학회 2014 공업화학 Vol.25 No.1

본 연구에서는 micro-contact printing을 통하여 니오븀 호일 표면 위에 균일한 에칭 pits를 형성하였다. 균일한 보호층을 형성하고자 전해연마의 효과를 확인하였으며, 기존의 O2 플라즈마 공정 없이 손쉽게 균일한 에칭 pits를 형성시킬 수 있는 조건을 확인하였다. 메탄올 혼합 전해질을 사용하여 10 min 동안 에칭을 진행한 결과 니오븀 호일 표면 위에 지름과 간격이 각각 10 μm와 5 μm로 잘 정렬된 에칭 pits를 관찰하였다. We describe the preparation of highly-ordered etching pits on the Nb foil through a micromachining. The effects of electro-chemical polishing on the formation of uniformly-patterned protective epoxy layer was investigated. Unlike the previous proc-ess using O2 plasma, well-ordered etched pits were prepared without any dry processes. As a result, the Nb foil with the well-ordered pits of 10 μm × 5 μm could be obtained by electrochemical etching in methanolic electrolytes for 10 min.

지하철 차량운용 문제에 대한 수리적 해법에 관한 연구

김경민(Kyung Min Kim),홍순흠(Soon-Heum Hong) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

This paper considers subway routing problem. Given a schedule of train to be routed by a railway stock, the routing problem determines a sequence of trains while satisfying turnaround time and maintenance restrictions. Generally, the solution of routing problem is generated from set partition formulation solved by column generation method, a typical integer programming approach for train-set. However, we find the characteristics of metropolitan subway which has a simple rail network, a few end stations and 13 departure-arrival patterns. We reflect a turn-around constraint due to spatial limitations has no existence in conventional railroad. Our objective is to minimize the number of daily train-sets. In this paper, we develop two basic techniques that solve the subway routing problem in a reasonable time. In first stage, we formulate the routing problem as a Min-cost-flow problem. Then, in the second stage, we attempt to normalize the distance covered to each routes and reduce the travel distance using our heuristic approach. Applied to the current daily timetable, we could find the subway routings, which is an approximately 14% improvement on the number of train-sets reducing 15% of maximum traveling distance and 8% of the standard deviation.

초기 성 학대 경험이 있는 여성 공황장애 환자의 임상적 특성

김경민,김민경,이강수,최태규,이상혁,Kim, Kyung Min,Kim, Min-Kyoung,Lee, Kang Soo,Choi, Tai Kiu,Lee, Sang-Hyuk 대한생물정신의학회 2016 생물정신의학 Vol.23 No.4

Objectives The objective of this study is to investigate differences of clinical characteristics between a healthy female control group and female panic disorder (PD) patients with early sexual abuse history (PD+S) and without early sexual abuse history (PD-S). Methods We examined data from 83 patients diagnosed with PD and 20 healthy control subjects. We divided the patients with PD into PD+S (32 patients) and PD-S (51 patients) to compare demographic and clinical characteristics. The following instruments were applied: the Stress coping strategies, the Beck Depression Inventory (BDI), the Panic Disorder Severity Scale, the Anxiety Sensitivity Index-Revised (ASI-R), the Albany Panic and Phobia Questionnaire (APPQ) and the NEO-neuroticism. Results Compared to the PD-S, the PD+S group showed higher scores in neuroticism and the APPQ. And, in the PD+S group, the scores of neuroticism were correlated with the ASI-R and APPQ subscale scores and the APPQ total scores were associated with the scores of BDI. Conclusions This study shows that female PD+S patients have higher scores in neuroticism and the APPQ than the PD-S group, and these factors are associated with the panic-related symptoms severity. It emphasizes the need of specific strategies considering the childhood abuse history such as early sexual abuse in clinical approach among patients with PD.

한국과 일본의 노인장기요양보험에 관한 문헌고찰

김경민,김남희,이정화,윤현서,박혜영,김혜진,Kim, Kyung-Min,Kim, Nam-Hee,Lee, Gung-Hwa,Yoon, Hyun-Seo,Park, Hye-Young,Kim, Hye-Jin 한국치위생학회 2017 한국치위생학회지 Vol.17 No.5

Objectives: The purpose of this study is to look into the health insurance systems and application in Korea and Japan in order to improve elderly people's quality of life. Their quality of life can be improved by upgrading the long term care systems; and extending treatment and prevention. Methods: This study is to examine long term care systems articles through content analysis in the National Health Insurance Service. Data were collected from the printed Internet and analyzed. Results: A part-time dentist system in elderly care facilities has trouble in taking care of old people's oral health due to both lack of time and operational difficulties. It is urgent to arrange dental experts who can permanently stay in care facilities and to build systems which can be managed periodically and continually. Conclusions: As having staff training for the efficiency and using the manpower in care facilities (care workers), it is necessary to solve the unequal medical service in oral health care for the elderly in Korea.

불안 관련 장애의 신경생물학적 이해

김경민,김민경,이상혁,Kim, Kyung-Min,Kim, Min-Kyoung,Lee, Sang-Hyuk 대한생물정신의학회 2014 생물정신의학 Vol.21 No.4

Anxiety disorders are characterized by dysregulation of neuroendocrine, neurotransmitter and neuroanatomical functions. Substantial advances in research method offered new insights into the neurobiologic mechanisms in anxiety disorders. Advances in molecular biology have enabled illumination of hormone and neurotransmitters that have important roles in anxiety. The neuroanatomic circuits related to anxiety are also being elucidated by improvements in neuroimaging technology such as structural and functional magnetic resonance imaging. This article reviews the research data in relation to the neurobiology underlying fear and pathologic anxiety and discusses their implications for development of biological treatments for anxiety disorders.

재가 치매노인을 돌보는 주 간호자의 스트레스와 건강상태

김경민,이은남,Kim, Kyung-Min,Lee, Eun-Nam 한국재활간호학회 2005 재활간호학회지 Vol.8 No.1

Purpose: The purpose of this study was to investigate the stress level and health status of primary caregivers living with demented elderly. Method: The subject was 92 primary caregivers who had been taking care of demented elderly at home. The research tools were a stress questionnaire and health status questionnaire. The data were collected through direct interview with a questionnaire in the B city, from February to March 2004. The data were analyzed by t-test, ANOVA, Pearson's correlation coefficients and Scheffe test using SPSS/PC 11.0 program. Results: The primary caregivers living with demented elderly showed slightly high level of stress and moderate level of health status. Moreover, there was a significant correlation between the stress level and the mental and the physical health status. Conclusion: Based on the results, we recommend the development of an intervention program to decrease the stress level of primary caregivers living with demented elderly for improving their health status.

DNA marker를 이용한 벼의 조직배양 효율 재선

김경민,Kim Kyung-Min 한국생명과학회 2006 생명과학회지 Vol.16 No.3

The purpose of this study is to improve the culturability of a indica type rice cultivar, IR 36, using DNA marker associated with the ability of plant regeneration in anther and seed culture. The varietal difference of ability of callus formation and plant regeneration was investigated in anther and seed culture of 8 rice cultivars. Three japonica rice cultivars showed to have better culturability than those of tongil and indica type genotypes. But two indica/japonica lines, 'MGRI 079' and 'MGRI 036', which were selected to have good culturability in previous study showed the highest regenerability (20%) in anther culture of 8 rice cultivars. Thirty four $BC_2F_4$ lines were selected by marker screening using RZ400 for 100 $BC_2F_4$ lines derived from a cross $'MGRI\;079/IR\;36^{^*3}'$. The frequency of callus formation of 30 $BC_2F_4$ lines was higher than those of 'IR 36' in anther culture of the selected $BC_2F_4$ lines. The ability of plant regeneration of 15 lines was higher than that of 'IR 36' in the seed culture of 34 $BC_2F_4$ lines. A promising line, $BC_2F_4-28$, was selected to have better culturability in the anther and seed culture of the $BC_2F_4$ lines. The heading date and grain shape of the $BC_2F_4-28$ was similar to 'IR 36'. In seed culture of 50 $BC_4F_3$ lines derived from a rice cross $'MGRI\;079/IR\;36^{^*5}'$, 11 lines including $BC_4F_3-3$ showed to have higher regenerability compared with 'IR 36'. The highest frequency of plant regeneration (11%) was obtained from $BC_4F_3-46$ in seed culture of the $BC_4F_3$ lines. 벼의 약 및 현미 배양효율과 관련된 DNA marker를 이용하여 인디카형 벼 품종인 'IR 36'의 조직배양 효율을 개선하기 위하여 실험한 결과를 요약하면 다음과 같다. MGRI집단의 약배양에서 식물체분화율이 높은 계통으로 선발된 'MGRI 079'와 'MGRI 036'의 약배양 효율은 각각 19.8%, 19.9%로 가장 높게 나타났다. 'MGRI 079'에 'IR 36'이 여교배되어 양성된 $BC_2F_4$ 100 계통에 대한 marker 검정을 실시하여 선발된 34 계통중 약배양에서 캘러스 형성률이 'IR 36'보다 높은 계통은 30계통이었고, 현미배양에서 'IR 36'보다 식물체 분화율이 높은 계통은 $BC_2F_4-28$ 외 14 계통이었다. $BC_2F_4$ 34계통 중에서 식물체분화능력이 높은 계통으로 선발된 $BC_2F_4-28$은 간장이 'IR 36'보다 큰 편이었으나 출수기와 미립특성은 'IR 36'과 비슷하였다. 'MGRI 036'에 'IR 36'을 반복친으로 여교배하여 양성된 $BC_4F_3$ 50계통의 현미배양을 실시한 결과 'IR 36'보다 식물체 재분화율이 높은 계통은 $BC_4F_3-3$ 외 10 계통이었고, 그중 $BC_4F_3-46$의 식물체 재분화율이 11%로 가장 높게 나타났다.

Gluconacetobacter sp. gel_SEA623-2를 이용한 Bacterial Cellulose 생산에 초산농도 및 유산균 혼합배양이 미치는 영향

김경민,김지현,양경월,Kim, Kyung min,Kim, Jihyeon,Yang, Kyong Wol 한국미생물학회 2014 미생물학회지 Vol.50 No.3

In this study, Gluconacetobacter sp. gel_SEA623-2 isolated from citrus that produces bacterial cellulose was used to examine the effect of initial concentration of acetic acid and mixed culture inoculated with Lactobacillus plantarum KCCM 80077 on productivity of bacterial cellulose. In mixed culture added with 0.5% acetic acid, the viable cell count increased from $2.4{\times}10^6CFU/ml$ to $1.1{\times}10^7CFU/ml$ after 14 days of culture, and total acidity was about 0.3% higher than single culture added with 0.5% acetic acid, which implies that additional lactic acid was produced by L. plantarum KCCM 80077. In single culture, although bacterial cellulose productivity was higher when the initial concentrations of acetic acid were 0.0% and 0.5%, than when it was 1.0%, there was no significant difference. However, in mixed culture, adding 0.5% acetic acid resulted in dry weight of $37.83{\pm}6.81g/L$ and thickness of $10.33{\pm}0.58mm$, showing a significant difference from that of single culture added with 1% acetic acid, $28.40{\pm}1.23g/L$ and $7.50{\pm}0.50mm$ (P<0.05). 본 연구에서는 bacterial cellulose를 생산하는 감귤에서 분리된 Gluconacetobacter sp. gel_SEA623-2를 이용하여 초기 초산농도 및 Lactobacillus plantarum KCCM 80077 유산균을 접종한 mixed culture가 bacterial cellulose 생산성에 미치는 영향을 알아보았다. 0.5%의 초산을 첨가한 mixed culture의 경우 초기 생균수가 $2.4{\times}10^6CFU/ml$에서 14일 동안 배양한 이후에 $1.1{\times}10^7CFU/ml$까지 증가하였고 total acidity가 0.5%의 초산을 첨가한 single culture와 비교하여 0.3% 가량 높게 측정되어 유산균에 의해 추가적으로 젖산이 생성된 것으로 판단된다. Single culture에서는 초기 초산농도가 0.0 및 0.5%일 때 1.0% 농도와 비교하여 상대적으로 높은 bacterial cellulose 생산성을 나타내기는 하였으나 유의적인 차이는 보이지 못하였다. 하지만 mixed culture에서는 0.5%의 초산을 첨가하였을 때 $37.83{\pm}6.81g/L$의 dry weight과 $10.33{\pm}0.58mm$의 thickness를 나타냄으로써 1%의 초산을 첨가한 single culture의 $28.40{\pm}1.23g/L$와 $7.50{\pm}0.50mm$의 생산량과 비교하여 유의적인 차이를 나타내었다(P<0.05).

오픈소스 하드웨어를 이용한 유아의 자유선택활동 관찰시스템의 설계 및 개발 연구

김경민,Kim, Kyung Min 한국스마트미디어학회 2018 스마트미디어저널 Vol.7 No.2

정보통신기술의 발전으로 교육분야에서도 시간, 장소 및 기기의 제약없이 학습이 가능한 스마트 교육이 활성화되고 있다. 그러나 주로 콘텐츠 기반의 교육 솔루션들이 제공되고 있고 학습자의 개별 특성을 파악하여 개별화된 학습을 제공하는 시스템 구축은 상대적으로 저조하다. 유아교육에서 자유선택활동은 중요한 놀이 활동이지만 교사들의 임상적 관찰에 의존함으로써 효율적으로 시행되지 못하고 있다. 최근 대두되고 있는 초연결성에 기반을 둔 사물인터넷 기술을 자유선택활동에 적용한다면 객관적이고 정형화된 데이터를 축적할 수 있고 이러한 데이터는 유아들의 개별화된 활동 유형과 놀이 형태 분석에 사용될 수 있을 것이다. 본 논문에서는 오픈소스 하드웨어 기반으로 사물인터넷 환경을 구축하여 유아들의 자유선택활동을 관찰하는 시스템을 설계하고 구현한다. 제안된 시스템은 유아들의 활동정보를 축적하여 분석 자료로 제공함으로써 교사들의 업무 경감과 개별 유아들에 대한 맞춤 교육 자료로 활용될 것이다. Along with the development of information and communication technology, smart education that can learn without restrictions of time, place and equipment is activated even in the field of education. Although smart education is provided with content-based training solutions, construction of a system that grasps individual characteristics of learners and provides personalized learning is relatively weak. The activity of free choice is an important play activity of early childhood education, but it is not implemented efficiently by relying on the clinical observation of the teacher. If the IoT(Internet of Things) technology based on Hyper-Connected is applied to free-choice activities, it is possible to provide the child's personalized activity type and play-form analysis based on objective and stylized data. In this paper, we design and implement a system to monitor the child's activity of free choice by building an IoT environment that is based on open source hardware. The proposed system provides children's activity information as objective data and will be used as teacher's work mitigation and custom training material for each child.