튜브형상 반응소결 탄화규소 부품의 시편크기에 따른 강도평가 유용성 고찰

김성원,이소율,오윤석,이성민,한윤수,신현익,김영석,Kim, Seongwon,Lee, Soyul,Oh, Yoon-Suk,Lee, Sung-Min,Han, Yoonsoo,Shin, Hyun-Ick,Kim, Youngseok 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.6

Reaction-bonded silicon carbide (RBSC) is a SiC-based composite ceramic fabricated by the infiltration of molten silicon into a skeleton of SiC particles and carbon, in order to manufacture a ceramic body with full density. RBSC has been widely used and studied for many years in the SiC field, because of its relatively low processing temperature for fabrication, easy use in forming components with a near-net shape, and high density, compared with other sintering methods for SiC. A radiant tube is one of the most commonly employed ceramics components when using RBSC materials in industrial fields. In this study, the mechanical strengths of commercial RBSC tubes with different sizes are evaluated using 3-point flexural and C-ring tests. The size scaling law is applied to the obtained mechanical strength values for specimens with different sizes. The discrepancy between the flexural and C-ring strengths is also discussed.

서브마이크론/나노 크기의 SiC 비율변화에 따른 ZrB₂-SiC 세라믹스의 열적, 기계적 특성

김성원,채정민,이성민,오윤석,김형태,Kim, Seongwon,Chae, Jung-Min,Lee, Sung-Min,Oh, Yoon-Suk,Kim, Hyung-Tae 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.6

$ZrB_2$-SiC ceramics are fabricated via hot pressing with different ratios of submicron or nano-sized SiC in a $ZrB_2$-20 vol%SiC system, in order to examine the effect of the SiC size ratio on the microstructures and physical properties, such as thermal conductivity, hardness, and flexural strength, of $ZrB_2$-SiC ceramics. Five different $ZrB_2$-SiC ceramics ($ZrB_2$-20 vol%[(1-x)SiC + xnanoSiC] where x = 0.0, 0.2, 0.5, 0.8, 1.0) are prepared in this study. The mean SiC particle sizes in the sintered bodies are highly dependent on the ratio of nano-sized SiC. The thermal conductivities of the $ZrB_2$-SiC ceramics increase with the ratio of nano-sized SiC, which is consistent with the percolation behavior. In addition, the $ZrB_2$-SiC ceramics with smaller mean SiC particle sizes exhibit enhanced mechanical properties, such as hardness and flexural strength, which can be explained using the Hall-Petch relation.

SpiraI Tube 내부에서의 3차원 유동 해석

김성원(Seongwon KIM),허남건(Nahmkeon HUR) 한국전산유체공학회 1998 한국전산유체공학회 학술대회논문집 Vol.1998 No.-

Spiral tube heat exchangers can find numerous applications in many engineering field. Flow in spiral tubes is interest to engineers due to occurrence of secondary flow which enhances the cross-sectional mixing and the heat transfer rate. In the present study. an incompressible viscous 3-D flow in spiral tubes with rectangular cross-section of various torsion rate and Reynolds number is studied by using a finite volume method. It is shown that the axial velocity profile is affected by the secondary flow motion. Because there is some difference from correlation proposed by Hur et al., a lot of analysis and arrangement of experimental results are needed. This study showed the results of variation of hydrodynamic entry length for torsion and Re numbers.

지터 측정을 통한 단방향 지연 시간 추정

김성원(Seongwon Kim),이혜원(Hyewon Lee),박태준(Taejun Park),최성현(Sunghyun Choi) 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.1

뇌병변 장애자녀를 돌보는 어머니가 인식하는 돌봄서비스 경험 -긴급돌봄서비스 이용 경험을 중심으로

김성원 ( Seongwon Kim ),이은진 ( Eunjin Lee ) 사단법인 아시아문화학술원 2021 인문사회 21 Vol.12 No.5

본 연구의 목적은 뇌병변 장애자녀를 돌보는 어머니가 인식하는 돌봄서비스의 욕구를 탐색하고 효율적인 서비스 운영 방안을 모색하기 위한 기초 자료를 제공하는데 있다. 연구 수행을 위해 긴급돌봄서비스를 이용한 어머니 11명을 모집 후 4그룹을 구성하여 초점집단인터뷰를 수행하였다. 수집된 자료는 주제분석을 통하여 분석하였으며, 주요 연구결과는 다음과 같다. 첫째, 장애자녀 돌봄은 ‘자신’만 가능, 둘째, 전적으로 돌봄을 제공할 수 없는 상황이 발생, 셋째, ‘보통의 일상’을 경험하고 되찾음으로 나타났다. 이러한 연구결과를 토대로 장애인복지실천에서 뇌병변 장애자녀의 돌봄서비스를 제공할 때 돌봄의 연속성을 확보하고 일상성을 확대할 수 있는 실천적 제언을 하였다. This study aims to explore the needs of care services perceived by mothers caring for children with cerebral palsy, thereby to provide basic data for exploring efficient service operation plan. To conduct the study, we performed a focused group interview with eleven mothers, four groups. The collected data were analyzed through thematic analysis, and the main research results were as follows: 1) Caring for children with disabilities is only possible ‘oneself’, 2) Situation arise where care cannot be provided entirely, and 3) Experience and reclaim ‘normal daily life.’ Based on these research results, we have suggested the practical implications that can ensure continuity of care and expand daily life when providing care services for children with cerebral palsy in welfare practice for the person with disabilities.

재사용 TPS용 다층 세라믹 단열재의 제조 및 특성

김성원(Seongwon Kim),오윤석(Yoon-Suk Oh),신재성(Jaesung Shin),김현준(Hyeonjun Kim),오범석(Bum-Seok Oh) 항공우주시스템공학회 2023 항공우주시스템공학회 학술대회 발표집 Vol.2023 No.05

강우입자분포를 고려한 시강우의 강우에너지 산정 연구

김성원(Seongwon Kim),정안철(Anchul Jeong),이기하(Giha Lee),정관수(Kwansue Jung) 한국지반환경공학회 2018 한국지반환경공학회논문집 Vol.19 No.12

우리나라에서 발생하는 대부분의 토양침식은 물에 의한 토양침식이며 강우와 밀접한 관계를 가진다. 강우로부터 발생하는 토양침식은 토지자원의 손실을 발생시키고 이후 하천에 유입되고 퇴적되어 하천수자원의 관리 및 이용에 많은 어려움을 주고 있다. 최근 기후변화의 영향으로 우리나라에서는 30mm/hr 이상의 집중호우의 발생횟수가 증가하고 있어 단기간에 토양침식이 발생할 가능성이 높아지고 있다. 본 연구에서는 강우의 물리적인 특성을 고려하기 위하여 누적분포함수를 이용하여 강우강도별 강우입자의 분포를 추정하고 단일 호우사상이 가지는 강우에너지를 계산하는 방법을 제안하고자 하였다. 강우에너지 산정공식을 개발하기 위하여 강우강도 0.254~152.4mm/hr에서 측정된 강우입자 자료를 이용하였다. 누적분포함수를 적용하여 산정된 강우에너지는 강우강도의 관계에서 멱함수형태로 증가하는 경향으로 나타났으며, 이 관계로 얻어진 식을 바탕으로 1~80mm/hr 강우강도의 강우 운동에너지를 산정한 결과 0.03~48.26Jm<SUP>-2</SUP>mm<SUP>-1</SUP>로 나타났다. 강우강도와 강우에너지의 관계를 바탕으로 강우에너지 식을 멱함수로 제시하였다. 본 연구에서 제안된 공식은 한시적으로 설치하는 침사지와 같은 시설물의 규모를 결정하는 계획의 토양침식량을 예측에 활용될 수 있을 것으로 판단된다. The occurrence of soil erosions in Korea is mostly driven by flowing water which has a close relationship with rainfalls. The soil eroded by rainfalls flows into and deposits in the river and it polluted the water resources and making the rivers become difficult to be managed. Recently, the frequency of heavy rainfall events that are more than 30 mm/hr has been increasing in Korea due to the influence of climate change, which creating a favourable condition for the occurrence of soil erosion within a short time. In this study, we proposed a method to estimate the distribution of rainfall intensity and to calculate the energy produced by a single rainfall event using the cumulative distribution function that take into account of the physical characteristics of rainfall. The raindrops kinetic energy estimated by the proposed method are compared with the measured data from the previous studies and it is noticed that the raindrops kinetic energy estimated by the rainfall intensity variation is very similar to the results concluded from the previous studies. In order to develop an equation for estimating rainfall kinetic energy, rainfall particle size data measured at a rainfall intensity of 0.254~152.4 mm/hr were used. The rainfall kinetic energy estimated by applying the cumulative distribution function tended to increase in the form of a power function in the relation of rainfall intensity. Based on the equation obtained from this relationship, the rainfall kinetic energy of 1~80 mm/hr rainfall intensity was estimated to be 0.03~48.26 Jm<SUP>-2</SUP>mm<SUP>-1</SUP>. Based on the relationship between rainfall intensity and rainfall energy, rainfall kinetic energy equation is proposed as a power function form and it is expected that it can be used in the design of short-term operated facility such as the sizing of sedimentation basin that requires prediction of soil loss by a single rainfall event.

시강우를 고려한 천천유역의 토양침식 및 퇴적 평가

김성원(Seongwon Kim),이대업(Daeeop Lee),정성호(Sungho Jung),이기하(Giha Lee) 한국지반환경공학회 2020 한국지반환경공학회논문집 Vol.21 No.4

최근 기후변화의 영향으로 단기간동안 높은 강우강도의 집중호우 빈도가 증가하고 있어 토양침식의 위험도가 증가할 것으로 보고 있다. 국내에서 적용하고 있는 토양침식 산정기법은 유역에서 발생하는 연 평균 토양침식을 예측하고 단기간에 발생하는 특별한 호우사상의 특징을 고려하여 침식을 예측하는 데 한계를 지니고 있다. 따라서 단기간에 발생하는 토양침식을 보다 합리적으로 해석하기 위해서는 단기 호우사상의 특징을 반영하고 침식과정을 물리적으로 해석할 수 있는 모형을 적용할 필요가 있다. 본 연구에서는 단기호우사상에 의한 토양침식을 산정하기 위하여 강우강도별 강우입자분포자료를 수집하였고 확률밀도함수를 적용하여 멱함수 형태의 강우운동에너지 산정공식을 제안하였다. 제안한 강우에너지 산정공식을 물리적 기반의 토양침식 모델에 적용하여 천천유역에서 발생한 2002년 2003년, 2007년 태풍 호우사상에 적용하였다. 그 결과, NSE는 0.036 증가하였고 RMSE는 4.995 ppm 감소한 결과를 보여 제안된 강우에너지 산정공식을 적용한 모형이 단기호우사상에 의한 유사유출을 잘 모의하는 것으로 나타났다. In recent years, the frequency of heavy rainfall associated with high rainfall intensity has been continuously increasing due to the effects of climate change; and thus also causes an increase in watershed soil erosion. The existing estimation techniques, used for the prediction of soil erosion in Korea have limitations in predicting the: average soil erosion in watersheds, and the soil erosion associated with abnormal short-term rainfall events. Therefore, it is necessary to consider the characteristics of torrential rainfall, and utilize physics-based model to accurately determine the soil erosion characteristics of a watershed. In this study, the rainfall kinetic energy equation, in the form of power function, is proposed by applying the probability density function, to analyze the rainfall particle distribution. The distributed rainfall-erosion model, which utilizes the proposed rainfall kinetic energy equation, was utilized in this study to determine the soil erosion associated with various typhoon events that occurred at Cheoncheon watershed. As a result, the model efficiency parameters of the model for NSE and RMSE are 0.036 and 4.995 ppm, respectively. Therefore, the suggested soil erosion model, coupled with the proposed rainfall-energy estimation, shows accurate results in predicting soil erosion in a watershed due to short-term rainfall events.

초고온용 ZrB<SUB>2</SUB>-계 세라믹스의 치밀화와 물성

김성원(Seongwon Kim),김형태(Hyung-Tae Kim),김경자(Kyung-Ja Kim),서원선(Won-Seon Seo) Korean Society for Precision Engineering 2012 한국정밀공학회지 Vol.29 No.3

특허문헌 텍스트 마이닝을 통한 비특허문헌 자동분류에 관한 연구

김성원 ( Seongwon Kim ),유동희 ( Donghee Yoo ),이수원 ( Suwon Lee ) 한국지식재산연구원 2024 지식재산연구 Vol.19 No.2

To file a patent or examine a submitted patent, one must perform a prior-art search that includes both patent and non-patent literature. Unlike patent literature, non-patent literature is not standardized and lacks a unified search system, thus necessitating separate searches for patents and non-patents. This renders the process particularly challenging for the latter. Hence, classification methods used in patent literature are applied to non-patent literature in this study, thus enabling a search system that operates in the same manner as patent-literature searches. The proposal includes the application of machine-learning techniques to recommend or automatically assign patent-classification codes to non-patent literature. For example, a process is reviewed in which international patent classificationcodes are automatically assigned to scholarly papers using machine-learning algorithms. Based on analyzing methods that leverage text-similarity and text-classification algorithms, the automatic classification of non-patent literature through patent-literature text mining is shown to be effective and thus warrants further research. Building a database of non-patent literature coded with patent classifications can result in a more efficient prior-art search process by allowing searches under a unified classification system for both patent and non-patent literatures.