Wear characteristics of Stellite6 and NOREM02 hardfaced SKD61 hot working tool steel at the elevated temperature

박나라,안동규 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.2

Recently, interest in hardfacing technology has steadily increased in effort to improve wear characteristics of hot forming dies. The objective of this paper is to investigate wear characteristics of Stellite6 and NOREM02 hardfaced SKD61 hot working tools steel at the elevated temperature. Stellite6 and NOREM02 superalloys are deposited onto the SKD61 hot working tool steel using the laser-aided direct metal rapid tooling (DMT) process. In order to examine the influence of the hardfacing materials on the hardness of hardfaced specimens, hardness experiments are performed beyond the full annealing temperature of the SKD61 material. Pin-on-disk experiments are carried out to examine wear characteristics, including the worn volume, the worn depth, the worn width, and the friction induced work hardening, of the hardfaced specimens at the elevated temperature. The morphology in the vicinity of the worn region is observed by a digital microscope and a scanning electronic microscope (SEM) to investigate the formation and the microstructure of the worn region. In addition, the efficiency of the hardfaced specimen is discussed via the comparison of wear characteristics of superalloy hardfaced specimens with those of the SKD61 specimen.

지방정부 인력구성의 다양성이 업무과정에 미치는 효과

박나라,이종수(李鍾秀) 한국지방자치학회 2010 韓國地方自治學會報 Vol.22 No.2

This is the first empirical study in Korea on the impact of human resource diversity in local government. The main purpose of this study is to examine the effects of human resource diversity, primarily focusing on the levels of innovation, transparency and responsibility of local governments in Korea. In this study, human resource diversity can be defined as the varied educational backgrounds of local bureaucrats, especially senior officials. The results of empirical analysis show that local governments with higher diversity tend to be superior in their innovation and acceptance of responsibility. However, the effect of diversity upon open government transparency is not proven. Therefore, this study proposes the following policy suggestions. First of all, the local government recruitment system should be open to a wider range of applicants for local government official positions, in order to manage human resource diversity effectively. Second, to prevent the problems caused by low diversity and its consequent nepotism, the local government personnel exchange system should be revitalized at both the intra- and inter-organization levels.

Wear Characteristics of Stellite6 and NOREM02 Hardfaced SKD61 Hot Working Tool Steel at the Elevated Temperature

박나라,안동규 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.12

Recently, interest in hardfacing technology has steadily increased in effort to improve wear characteristics of hot forming dies. Theobjective of this paper is to investigate wear characteristics of Stellite6 and NOREM02 hardfaced SKD61 hot working tools steel atthe elevated temperature. Stellite6 and NOREM02 superalloys are deposited onto the SKD61 hot working tool steel using the laseraideddirect metal rapid tooling (DMT) process. In order to examine the influence of the hardfacing materials on the hardness ofhardfaced specimens, hardness experiments are performed beyond the full annealing temperature of the SKD61 material. Pin-on-diskexperiments are carried out to examine wear characteristics, including the worn volume, the worn depth, the worn width, and thefriction induced work hardening, of the hardfaced specimens at the elevated temperature. The morphology in the vicinity of the wornregion is observed by a digital microscope and a scanning electronic microscope (SEM) to investigate the formation and themicrostructure of the worn region. In addition, the efficiency of the hardfaced specimen is discussed via the comparison of wearcharacteristics of superalloy hardfaced specimens with those of the SKD61 specimen.

한국 정치학 연구의 현재와 미래: 2000-2019 <한국정치학회보> 분석

박나라 이화여자대학교 이화사회과학원 2020 사회과학연구논총 Vol.36 No.2

본 논문은 2000년대 이후 한국 정치학 연구의 경향을 다각도로 검토하여, 최근의 성과와 한계를 조명하고자 한다. 2000년부터 2019년까지 <한국정치학회보>에 게재된 논문 전수를 대상으로 분야 및 주제, 지역적 범위, 방법론, 수행 방법 등 연구의 핵심 요소를 메타분석한 결과는 다음과 같다. 첫째, 한국 현실 정치에 정책적 함의를 제공할 수 있는 정치과정・제도 분야가 우세한 가운데, 정치학적 논의의 이론적 바탕을 이루는 정치철학・사상 분야도 굳건히 자리를 지켰다. 둘째, 한국 정치학계에서의 논의인 만큼 한국이 주로 분석 대상이 되었지만, 전지구적 범위, 복수 지역 혹은 비국가 행위자 등 전통적 국민 국가의 경계를 넘어서는 대상들이 분석되었다. 셋째, 정치철학・사상 분야를 제외하더라도 정성적 접근 방법을 취한 연구가 과반수이상을 차지하고 있지만, 계량적 방법을 사용하는 논문이 눈에 띄게 증가하고 있다. 넷째, 학문 환경의 변화로 인해 공동 연구가 증가하는 한편, 영문으로 작성된 논문이 국내에 발표되는 빈도는 증감을 거듭하고 있다. This study examines multiple facets of political science research in Korea since the 2000s, and the progress and limitations of the recent literature. It mainly analyzes various components of research including research fields, topics, geographical scope, methodology, and methods by conducting a meta-analysis of all the articles published in the Korean Political Science Review from 2000 to 2019. First, a majority of studies delve into political processes and institutions, which would offer practical policy implications for Korean politics, whereas an array of research on political philosophy and theory exists to form a theoretical foundation for political discussion. Second, quite naturally, Korean academia primarily explores Korean cases, while it also studies global, multiple, and non-state cases, which are beyond the traditional framework revolving around nation states. Third, leaving political philosophy and theory aside, an abundance of research takes a qualitative approach, although there is a steep increase in the number of studies employing quantitative methods. Fourth, due to changes in the academic environment, collaboration among researchers has been extended, and the number of articles written in English has fluctuated.

질적 연구의 심화와 확장: 한국 정치학 연구에서의 근거이론 방법 적용 가능성

박나라 한국정치정보학회 2020 정치정보연구 Vol.23 No.2

This article examines grounded theory, one of the most preferred qualitative research methods in the social sciences, to help open a new horizon in the field of political methodology in Korea. A survey of Korean political science research in recent decades shows that despite the increasing predominance of quantitative, statistical methods, a number of studies still used non-quantitative methods, among which only a few followed qualitative methodology in the strict sense. In addition, there has not been much scholarly discussion on qualitative research methodology. In this regard, the grounded theory method, aiming at constructing theory grounded in data under the qualitative-inductive paradigm, would be able to bring balance to the methodological spectrum, which is dominated by the quantitative-deductive paradigm, to test existing theories. Ultimately, grounded theory will contribute to addressing the gap between grand theory and reality and to contextualizing middle-range theories, especially in Korean politics, comparative politics, and international relations research. 본 논문은 한국 정치학 연구 방법론 논의의 새로운 지평을 열기 위해, 대표적인 사회과학 질적 연구 방법의 하나인 근거이론 방법에 대해 고찰한다. 최근 한국 정치학 연구에서 계량적, 통계적 방법의 증가에도 불구하고 여전히 비계량적 방법을 사용한 논문이 상당수를 차지하지만, 질적 연구 방법(methods)에 의거하여 자료를 분석한 논문은 많지 않으며, 질적 연구방법론(methodology)에 대한 체계적인 고찰도 찾아보기 어렵다. 이러한 상황에서 질적-귀납적 패러다임 하에서 “자료에 근거한 이론 창출”을 목표로 하는 근거이론 방법(grounded theory method)은 기존 이론에 대한 검증을 금과옥조로 삼는 양적-연역적 패러다임의 다른 한 쪽에서 방법론적 균형을 가져올 것이다. 궁극적으로 근거이론은, 특히 한국정치, 비교정치, 국제정치 등의 분야에서, 거대이론과 현실 세계를 이어주는 중범위이론이 한국적 맥락에서 생성되도록 하는 데 많은 기여를 할 것으로 기대한다.

펄스전류활성소결장치를 이용한 다공성 Fe-Cu-C계 합금 제조 및 기계적 특성 평가

박나라,김기열,이병현,김태완,송준혁 한국기계기술학회 2020 한국기계기술학회지 Vol.22 No.3

Porous Fe-Cu-C alloy was sintered by Pulsed Current Activated Sintering(PCAS) method within 10 min from horizontal ball mill mixture. The relative density of Fe-20wt.%Cu-0.8wt.%C alloy fabricated by PCAS method was 91%. The average hardness of the Fe-20wt.%Cu-0.8wt.%C alloy was HRB 92. The phase analysis, microstructure and composition information of the sintered alloy were investigated by using XRD, FESEM, EDAX.

Fabrication of Nanopowder and Consolidation of Nanocrystalline 5Ni0.6Fe0.4-Al2O3 Composite by Rapid Sintering

박나라,최명규,박제신,김원백,손인진 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.5

Nano-powders of 5Ni0.6Fe0.4 and Al2O3 were synthesized from 3NiO and 2FeAl powders by high energy ball milling. Nanocrystalline 5Ni0.6Fe0.4-Al2O3 composite was consolidated by pulsed current activated sintering method within 2 min from mechanically alloyed powders of Al2O3 and 5Ni0.6Fe0.4. The average hardness and fracture toughness values obtained were 990 kg/mm2 and 7.5 MPa·m1/2, respectively. Nano-powders of 5Ni0.6Fe0.4 and Al2O3 were synthesized from 3NiO and 2FeAl powders by high energy ball milling. Nanocrystalline 5Ni0.6Fe0.4-Al2O3 composite was consolidated by pulsed current activated sintering method within 2 min from mechanically alloyed powders of Al2O3 and 5Ni0.6Fe0.4. The average hardness and fracture toughness values obtained were 990 kg/mm2 and 7.5 MPa·m1/2, respectively.

한국 행정학 질적 연구의 방법(론)상 논점: 2000-2019년 한국행정학보 게재 논문 메타 분석

박나라,윤선우 한국행정학회 2022 韓國行政學報 Vol.56 No.1

In this article, we mainly discuss three critical points regarding qualitative research methods and methodology based on a meta-analysis of research published in the Korean Public Administration Review between 2000 and 2019. First, many case studies have not made a comparison among plural cases, but only examined a single case without developing a theoretical framework of their own. Second, in-depth interviews have not been rigorously analyzed, but rather quoted as supplementary evidence to increase the validity of quantitative analysis. This invites caution because the in-depth interview is a qualitative research method whose primary purpose is to collect data that then needs to be substantively parsed. Third, most content analysis articles have been conducted quantitatively with frequency analyses of keywords, rather than qualitatively with semantic analysis of their meanings. In conclusion, we suggest boundary spanning through an active combination of multiple research methods and deepening of qualitative research through mixed methods integrative research design. To improve the quality of qualitative research, we recommend that public administration scholars build an institutional and normative foundation for fully fledged academic development by strengthening education in qualitative research methodology and methods. 본 논문은 2000년부터 2019년까지 한국행정학보에 게재된 일반논문들의 방법(론)적 경향성을 검토하고 질적 연구 방법과 관련한 세 가지 논점을 도출하였다. 첫째, 단일 사례연구의 비중이 증가하고 있으나 별도의 이론적 분석틀이 없거나 기존의 수입 모형 및 이론을 그대로 한국적 맥락에 적용하는 형태로 수행된 경우가 많았다. 둘째, 질적·양적연구에서 심층면담 자료가 널리 활용되고 있으나 단순 인용하거나 분석 결과를 보고하지 않는 등 엄밀한 분석이 이루어지고 있지 않았다. 셋째, 내용분석에서 양적 접근이 주를 이루는 가운데, 내용분석을 체계적인 분석 방법으로 이해하고 분석한 경우가 드물었다. 본 논문은 이러한 논점들에 대한 제언으로, 다양한 질적 방법의 활용을 통한 질적 연구의 확대와 혼합적 연구 설계를 통한 질적 연구의 심화를 제시하였다. 궁극적으로 질적 연구 방법(론) 교육을 통해 연구 방법의 기술적 측면뿐만 아니라 제도적, 체계적으로 질적 연구 윤리를 추구하는 풍토를 만들어 나가기 위해 한국 행정학 연구 공동체가 집합적인 노력을 경주해 나가기를 기대한다.

고주파유도가열 연소합성에 의한 4.25 Co_0.53Fe_0.47-Al₂O₃ 복합재료 제조

박나라,남궁훈,고인용,손인진,Park, Na-Ra,NamKung, Hoon,Ko, In-Yong,Shon, In-Jin 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.2

Nanopowders of $Co_3O_4$ and FeAl were fabricated by high energy ball milling. Dense 4.25 $Co_{0.53}Fe_{0.47}-Al_2O_3$ composite was simultaneously synthesized and consolidated by high frequency induction heated combustion method within 2 min from mechanically activated powders. Consolidation was accomplished under the combined effects of a induced current and mechanical pressure of 80 MPa.

COVID-19 세계적 대유행으로 인한 대학생의 지식, 정신건강실태 및 감염예방행위

박나라,류지홍,남민아,소애영 다문화건강학회 2021 다문화건강학회지 Vol.11 No.1

Purpose: This study examined the knowledge, mental health status, and infection prevention behavior of university students about COVID-19 epidemic. Methods: A survey was conducted on 180 students at the university in W city from 2020.10.19 to 2020.10.23. The research tools included a fear measurement tool(nine questions) developed by the KSTSS, and GAD-7 and PHQ-9, which measure anxiety and depression. The COVID-19 knowledge and infection prevention behaviors were developed and used by researchers referring to the 'Coronavirus Infectious Disease-19 Prevention National Code of Conduct' and '2020 Living Prevention Guidelines(draft)' of the KDCA. Results: Students' knowledge about COVID-19 was high at 10.14±0.87 out of 11, fear at 17.12±0.58, anxiety at 3.28±4.19, and depression at 4.17±4.96. Prevention health behavior was high with 4.04. The higher fear, the higher anxiety and depression. The better subjective health status, the lower anxiety and depression, and the higher prevention health behavior. Conclusion: Students' fear, anxiety and depression about COVID-19, alcohol consumption, exercise, and subjective health was correlated. Mental health promotion intervention programs are need.