고정밀 신관 부품의 MIM 공정에 관한 연구

서정화,강경훈,Seo, Jung-Hwa,Kang, Kyeoung-Hoon 한국군사과학기술학회 2012 한국군사과학기술학회지 Vol.15 No.3

During the past two decades, Metal Injection Molding(MIM) has become a very competitive technology to fabricate small, precise and complex-shaped parts in large quantities. In this research, the applicability of MIM technology in the mass-production of the high precision fuze parts to save manufacturing cost was investigated. The water-atomized 17-4PH stainless steel powder, one of the best corrosion-resistant high strength materials, was injection-molded into real-shape fuze part and flat tensile specimens. The injection-molded parts were thermally debound in hydrogen gas flow without solvent extraction. Sintering of the debound parts was carried out in vacuum at temperatures ranging from $1150^{\circ}C$ to $1370^{\circ}C$. The sintering behavior, mechanical properties, dimensional precision, corrosion resistance of the MIMed 17-4PH stainless parts were investigated. It was found that almost all the properties of the MIMed parts were comparable to those of the mechanically machined parts. Also, actual military field tests using both MIMed and mechanically machined fuze parts were performed as well and were found to be very successful.

A Study on the Revitalization Underground Shopping Center : Focusing Jung-Ang Underground shopping center

남세희(Sea Hee Nam),서정화(Jung Hwa Seo) 한국IT마케팅학회 2015 Journal of Information Technology and Management Vol.3 No.1

The population of the city due to the increase of the vehicle due to the concentration of pedestrians and the new structure of the underground facility was necessary, this underground space to get the economic effects of underground shops. Underground shoping center is a place where it can be effectively supplied in the city as the city that the demand for space is increased to expand continuously. Underground shopping center getting larger, It is the atmosphere to attract Underpass, users of transportation such as subways, as well as for reading pedestrians also the ground of pedestrians, but it's still the law associated with the underground system there are many problems with their flaws. [3] Therefore, This study is to understand the concepts and characteristics of the Underground shoping center, To identify the problems that occur, such as in underground shopping malls, Jung-Ang underground shopping center proposes the activation measures.

스포츠이벤트 시설의 서비스스케이프가 관람가치 및 재관람의도에 미치는 영향

서정화(Jung Hwa Seo),문보영(Bo Young Moon) 융합관광콘텐츠학회 2017 융합관광콘텐츠연구 (JCTC) Vol.3 No.2

This The purpose of this study is to examine the influences of the service scene on the spectacle value to the sports event facilities and the intention to revisit. Sports event facilities are not competitive, it is necessary to provide a servicescape appropriate to the desire and the value of visitors. The sample of this study is Seongnam FC to Jeju FC on July 20, 2016, Seoul FC on August 3, Jeonnam FC on August 10, and Suwon FC and Cheilu FC on September 17 at K-League Classic. Surveyed and collected 250 visitors who visited the Seongnam Tancheon Sports Complex individually and analyzed them by judicial sampling method. The results of this analysis are as follows. First, this research confirmed that the service landscape of sports event facilities had a positive effect on the spectator value. Second, the value of visitors has a positive effect on the intention to revisit. Third, the service landscape of sport event facilities has a positive effect on the intention to revisit.

가정용 8㎾h급 에너지 저장 시스템

서정화(Jung-Hwa Seo),이우원(Woo-Won Lee),이수원(Su-Won Lee),한희민(Hee-Min Han),한기준(Ki-Jun Han),서광덕(Kwang-Duk Seo) 전력전자학회 2012 전력전자학술대회 논문집 Vol.2012 No.7

대학가 역세권의 보행 및 공간특성에 관한 연구

서정화(Seo Jung-Hwa),이명훈(Lee Myeong-Hun),전병혜(Jun Byung-Hye) 대한국토·도시계획학회 2008 國土計劃 Vol.43 No.2

볼 베어링 및 가스 포일 베어링으로 지지되는 소형 고속전동기의 진동 특성

서정화(Jung Hwa Seo),김태호(Tae Ho Kim) 한국트라이볼로지학회 2019 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.35 No.2

High-speed rotating machinery requires low cost and reliable bearing elements with low friction, stable rotordynamic characteristics, and a simple design. This study experimentally evaluates the effects of bearing-support elements on the vibrational characteristics of a small-sized, high-speed permanent magnetic motor. A series of coast down tests from 100 krpm characterize the vibrational behaviors, rotor displacement, and housing acceleration of motors supported by ball bearings, ball bearings with a metal mesh damper, and gas foil bearings, respectively. Two eddy-current sensors installed in the horizontal and vertical directions measure the displacement of the rotor at its front nut, and a 3-axis accelerometer attached to the motor housing measures the housing acceleration. The test results reveal that synchronous (1X) vibration components most significantly affect the rotor displacement and housing acceleration, independent of the bearing-support elements. The motor supported by the deep-groove ball bearings results in the largest rotor vibrations increasing with speed; this is due to the absence of a damping mechanism. Additionally, the metal mesh damper effectively reduces the rotor displacement, housing acceleration, and sound-pressure level in the high-speed region (i.e., above 40 krpm), thus implying its substantial damping performance when installed on the outer race of the ball bearing. Lastly, the gas foil bearing supported motor yields the smallest rotor displacement, housing acceleration, and lowest sound-pressure level because of its hydrodynamic airborne operation, which does not require rolling elements that may cause mechanical friction and vibrations.

[특집 : 노숙인, 공동체로부터 소외된 사람들] 여성노숙인의 존재와 삶

서정화(Seo Jung Hwa) 고려대학교 아세아문제연구소 2005 亞細亞硏究 Vol.48 No.2

For last several years the homeless women continuously increase and specially the homeless women with children considerably go on increasing. Nevertheless the government neglect the counterplan for a small number.<br/> The homeless women living in the street with maladaptation on shelter, mentally ill etc. are exposed physical violence and rape as well as difficulty in board and lodging.<br/> There are various ways as strategy for survival in the street; 'hiding and concealment - hiding oneself not be exposed', 'bringing under control - be his love or live together with the homeless man', 'utilizing resources within and without-sell one's favors for income or receive relief on making a tour of the church'.<br/> Life in shelter is a space for the homeless women to prepare self-support, but there is another difficulty in adapting themselves to the shelter. In case of the failure in adapting oneself to the new rule and the new life in the shelter, the homeless -women used to do get out of the shelter. when the homeless women establish herself in the shelter after going through the course of adapting like 'adapting new rule', 'being acknowledged in shelter' etc., they get to be having a desire for going out of the shelter and supporting herself.<br/> For self-support, employment for earning one's living holds a key post. The homeless women with children are mostly easy to be employed because they are mentally and physically healthy. But the single homeless women are difficult in employment on account of mentally ill. It demand another counterplan for self-support because the homeless women with children are one thing and the single homeless women are another.<br/> In case of the homeless women with children, it first needs to support a dwelling and self-support. But in case of the single homeless women with a chronic disease, it needs common dwelling and common working place.

A pH-Neutral Polyelectrolyte Hole Transport Layer for Improved Energy Band Structure at the Anode/PTB7 Junction and Improved Solar Cell Performance

Jung Hwa Seo(서정화),강주환,Yeasin Khan,Bright Walker 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.2

임상연구 : 삼차원 단층촬영을 이용한 중심정맥의 쇄골상부 도자법에 대한 해부학적 고찰

서정화 ( Jeong Hwa Seo ),이활 ( Whal Lee ),정철우 ( Chul Woo Jung ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.50 No.4

Background: The current study aimed at elucidating the anatomical basis for a supraclavicular approach for central venous catheterization using three-dimensional computed tomography (3D-CT). Methods: Retrospective review of CT images from 60 adult patients with normal body build was performed using 3D-CT reconstruction. Right-sided approach was assumed, and the skin entry point was decided as a point above the subclavian vein at the supraclavicular fossa. Measured parameters were; angles of the clavicle (Aclv) and the subclavian vein (Ascv) to the coronal plane, the distance from the clavisternomastoid angle to the skin entry point (Dse), the optimal angle of needle insertion (Ains) targeting the confluence between the internal jugular vein and the subclavian vein, the distance from the skin entry point to the confluence (Dconf), and the diameter of the confluence (Dia). Descriptive statistics were performed for the measured values. Correlation test was performed between Ascv and Aclv. Results: Measured values were; Aclv = 8.0˚, Ascv = 5.7˚, Dse = 12.5mm, Ains = 40˚, Dconf = 20.5mm, and Dia = 18.1mm. Ascv demonstrated positive correlation with corresponding Aclv (r = 0.494, P < 0.001). Conclusions: Optimal guideline for the supraclavicular approach can be provided via 3D-CT investigation. Forty degrees of needle direction to the sagittal plane and parallel to the posterior surface of the clavicle, at 1.3 cm posterior to the clavisternomastoid angle insures proper puncture of the confluence without anticipated complications. (Korean J Anesthesiol 2006; 50: 373~8)

경기 일부 지역 대학생에서 식생할지침 실천도에 따른 나트륨 관련 식습관 및 식행동 분석 연구

배윤정,노승은,서정화,손주희,이미진,정다운,Bae, Yun-Jung,No, Seung-Eun,Seo, Jeong-Hwa,Son, Joo-Hee,Lee, Mi-Jin,Jung, Da-Woon 한국식품영양학회 2015 韓國食品營養學會誌 Vol.28 No.3

The purpose of this study was to evaluate the sodium-related dietary attitudes, behaviors, and nutritional knowledge in university students according to the practice of dietary guidelines for Koreans established by the Ministry of Health and Welfare, Republic of Korea. Based on the total practice score related to the dietary guidelines (PDG), we classified subjects into a "low practice of the dietary guidelines (LPDG)" group (n=94, male=43, female=51) (total score of PDG ${\leq}13$) and a "high practice of the dietary guidelines (HPDG)" group (n=56, male=32, female=24) (total score of PDG >13). Subjects were asked about general characteristics, lifestyle, salt-related dietary attitudes, behaviors, and nutritional knowledge using a questionnaire. The LPDG group had more subjects who were breakfast skippers (p<0.001) compared to the HPDG group. The LPDG group (31.26) had a significantly lower score in terms of salt-related dietary attitudes compared to the HPDG group (33.77) (p=0.0042). The score for salt-related dietary attitudes was significantly higher in the HPDG (32.52) group than in the LPDG (29.91) group (p=0.0041). There was no significant difference in the total score for salt-related nutrition knowledge between the groups. The correlation analysis indicated that the dietary guidelines practice score had a positive correlation with the salt-related dietary attitude score (r=0.3593, p<0.0001) and the dietary attitude score (r=0.3443, p<0.0001) after adjustments for sex. These results show that the degree of adherence to the dietary guidelines for adults may be related to sodium-related dietary attitudes, behaviors, and nutrition knowledge.