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김춘식 ( Choon Sig Kim ),이광수 ( Kwang Soo Lee ),손영모 ( Young Mo Son ),조현서 ( Hyun Seo Cho ) 한국산림과학회 2013 한국산림과학회지 Vol.102 No.4
This study was conducted to evaluate age-specific and generalized allometric equations and biomass expansion factors (BEFs) for each tree component across three age-sequence stands (35-year-old, 51-year-old, 62-year-old) of black pine (Pinus thunbergii Parl.) in Jinju, located in the western part of Gyeongnam province, Korea. Biomass in each tree component, i.e. foliage, branch, and stem, was quantified by destructive tree harvesting. Allometric regression equations were significant (P<0.05) with diameter at breast height (DBH) or combination of DBH and height (DBH2H) accounting for 55-98% of the variation (as indicated by coefficients of determination, R2) in aboveground biomass except for foliage biomass of the 62-year-old stand. Generalized allometric equations can be used to estimate the biomass of black pine stands because the slopes of age-specific equations over 35-year-old stands were not significantly different by the age-sequence. The stem density and biomass expansion factor (BEFs) were not significantly different (P>0.05) from different stand ages and ranged from 0.45 to 0.51 g cm-3, and from 1.32 to 1.38, respectively. The results indicate that allometric equations, stem density and aboveground BEFs in the matured black pine over 35-year-old are little influenced by different stand ages.
CO<sub>2</sub>고정화한 제강슬래그와 발전소 바닥재를 활용한 저강도 고유동 채움재의 특성
조용광,김춘식,남성영,조성현,이형우,안지환,Cho, Yong-Kwang,Kim, Chun-Sik,Nam, Seong-Young,Cho, Sung-Hyun,Lee, Hyoung-Woo,Ahn, Ji-Whan 한국에너지학회 2018 에너지공학 Vol.27 No.2
폐자원으로 분류되는 화력발전소의 석탄재와 제강슬래그(KR슬래그)를 주 재료로 활용하여 저강도 고유동채움재를 제조하였다. 산업부산물의 활용방안을 확대하고 중금속 용출 억제 등의 환경적 안정성을 확보하기 위해 화력발전소 바닥재(bottom ash)와 KR슬래그는 7:3으로 혼합하여 탄산화반응($CO_2$고정화)을 실시하였다. 연구결과 석탄바닥재의 기공이 많아 $CO_2$고정화 물질 함량이 증가할수록 물비율이 증가하였다. 배합 중 분체함량이 증가할수록 블리딩율이 저하되는 것을 확인하였다. 1종 보통 포틀랜드 시멘트(OPC)함량이 감소할수록 수화반응의 활성화가 저하되어 압축강도는 감소하였다. 하지만 배합 조성을 적절히 조절할 경우 저강도 고유동 채움재가 요구되는 2.0MPa의 압축강도는 충족시킬 수 있는 결과를 확보하였다. In this study investigated the Controlled Low Strength Materials using coal ash and steel slag(KR slag) as the main material in the thermal power plant classified as waste resource. Bottom ash and KR slag are mixed at a ratio of 7: 3 to expand the use of industrial by-products through carbonate($CO_2$-fixation) reactions and inhibit the exudation of heavy metals. The results showed that the water content increased as the content of bottom ash increased. It was confirmed that as the powder content increased, the bleeding ratio decreased. Also, as the content of one kind of ordinary portland cement (OPC) decreased, activation of hydration reaction decreased and compressive strength decreased. However, when the mixed composition is appropriately adjusted, the compressive strength of 2.0 MPa required for the controlled low-strength material can be satisfied.
조재웅(Cho Jae-Ung),김춘식(Kim, Choon-Sik),이희성(Lee, Evan),김영춘(Kim, Young-Choon) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.10
압입 방식으로서 경량화된 부품이 매우 균질한 정밀도로 생산이 되며 프레스의 기술이 향상되고 있다. 압입 방식으로 조립하였을 시 핀과 구멍사이에는 압축력에 의한 변형력이 발생되고 접촉면이 손상을 입는다. 따라서 본 연구에서는 CATIA 프로그램을 이용하여 3D 모델링하였으며, ANSYS 프로그램을 통하여 압입 접촉된 평면에서 손상평가를 하였다. 해석결과, 핀이 들어갈 때 PCB판에 작용하는 하중은 약 21.3N인 것으로 확인되었으며, PCB판이 Pin에서 빠져나올 때의 하중은 약 19.24N으로 나타났다. 또한 구조 해석결과, Pin 1이 본 연구 모델의 모든 부품들 중에서 가장 최대응력이 많이 발생하므로, 대표적으로 Pin 1의 최대 등가응력이 192.96MPa로 나타났다. 압입 접촉 손상 특성을 규명하고 본 연구결과를 실제의 압입 공정의 설계에 응용함으로서 그 파손을 방지하고 내구성을 평가할 수 있다고 사료된다. Lightweight parts with very uniform precision are manufactured by an indent method and the press technique has been improved. Upon assembly with an indent method, a deformation force due to the compressive force occurs between the pin and hole and the contact surface is affected by damage. Therefore, a 3 dimensional model was made using the CATIA program and the damage on the surface contacted with indent was estimated through the ANSYS program in this study. In the analysis result, the maximum load applied at the PCB plate was 21.3 N when the pin goes through the PCB plate. When PCB plate came out of the pin, the maximum load was 19.24 N. As the structural analysis result, the maximum equivalent stress of Pin 1 was 192.96MPa because the maximum stress occurs at Pin 1 among all parts of this study model. By examining the damage property of the contacted indent and applying this study result to the design of real indentation, the damage can be prevented and the durability can be estimated.
제대영 ( Dai Young Jae ),서희영 ( Hui Yeong Seo ),조현서 ( Hyun Seo Cho ),안현철 ( Hyun Chul Ahn ),김춘식 ( Choon Sig Kim ) 한국산림과학회 2015 한국산림과학회지 Vol.104 No.1
This study was carried out to evaluate the growth characteristics, carbon and nitrogen content of containerized 1-0 Chamaecyparis obtusa seedlings at various levels of fertilizer (2 g/L, 1 g/L, control) and three container volumes (500 mL, 400 mL, 320 mL). The growth of root collar diameter was highest in the 2 g/L (3.14 mm), followed by the 1 g/L (2.75 mm) and control (2.41 mm) treatments, while the height of seedling was significantly higher in the 1 g/L (21.88 cm) than other treatments (2 g/L: 20.92 cm; control: 19.06 cm). The growth of root collar diameter by container volume was better in the 500 mL than in the 320 mL. Dry weight of seedling was the highest in the 1 g/L (4.41 g seedling.1), followed by the control (3.67 g seedling.1) and the 2 g/L (2.92 g seedling.1) treatments. The dry weight of seedlings by container volume was significantly higher in the 500 mL than in the 320 mL. Nitrogen concentration in foliage was ranged from 1.51% in the control to 2.45-2.60% in the fertilizer treatments. However, carbon concentration of seedlings was not affected by the fertilizer or the container volume treatments. The growth of seedlings following planting in mountain area was better in the fertilized seedlings compared with in the unfertilized seedlings. The results indicate that the 1 g/L fertilization was an optimum rate for growth following planting of Chamaecyparis obtusa seedlings.
PCB 판에 대한 핀의 이동 공정에 따른 압입파괴 평가
김영춘(Kim, Young-Choon),김춘식(Kim, Choon-Sik),이희성(Lee, Evan),조재웅(Cho Jae-Ung) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.12
기계적 체결 방식으로 볼트와 너트를 이용한 결합 방식과 리벳이나 핀이 널리 사용되고 있다. 압입 방식은 다른 생산방법에 비하여 쉽게 가공 가능하며 재료의 인성이 우수하다. 하지만 실제적으로 압입방식으로 생산하는 과정에서 균열 이 발생될 수 있는 경우가 많다. 따라서 본 연구에서는 CATIA 프로그램을 이용하여 핀이 PCB 판으로 들어가고 나가는 두 가지 경우의 모델을 만들고 ANSYS 프로그램을 이용하여 유한요소 해석을 수행하였다. Case 1 및 2의 경우에 핀이 PCB판에 들어갈 때, PCB판에서 작용되는 최대 하중은 각각 79.708N과 90.277N이다. 그리고 Case 1 및 2의 경우에, PCB판이 Pin에서 빠져나올 때의 최대 하중은 각각 63.783N과 33. 75N으로 각각 나타났다. 본 연구의 결과를 실제 압입 공정의 설계에 응용한다 면 그 파손방지 및 내구성을 평가하는 데에 활용이 클 것으로 사료된다. Assembly using a bolt and nut, and rivet or pin have been used widely for forming mechanical joints. The indent method is an easier process than other manufacturing techniques and the toughness of the material is excellent. On the other hand, there are many cases in which the cracks occur on the manufacturing process as the indent method. Therefore, two kinds of models, in which a pin goes into and out PCB plate in this study were developed using the CATIA program and finite element methods were performed using the ANSYS program. When a pin was passed through a PCB plate in cases 1 and 2, the maximum loads applied to the PCB plate were 79.708N and 90.277N, respectively. When the PCB plate came out of the pin in cases 1 and 2, the maximum loads were 63.783N and 33.75N, respectively. The damage prevention and durability can be improved by applying the study results to the design of real indentation.
재유화형 EVA 수지를 함유한 광산 폴리머-차수재의 물성 평가
조용광(Yong-Kwang Cho),남성영(Seong-Young Nam),김춘식(Chun-Sik Kim),이형우(Hyoung-Woo Lee),조성현(Sung-Hyun Jo),안지환(Ji-Whan Ahn) 한국고분자학회 2018 폴리머 Vol.42 No.4
저투수성 광산 차수재를 제조하기 위해 재유화형 ethylene vinyl acetate(EVA) 분말수지를 혼입한 폴리머-차수재를 제조하였다. EVA 수지는 방수성, 및 내구성이 우수하여 여러 산업에서 다양하게 활용되고 있다. 본 연구에서는 시멘트와 골재 사이의 공간을 EVA 폴리머 필름으로 채워 기초 물성 향상 및 수밀성 향상을 통한 우수한 차수성능을 발현하고자 하였다. 연구결과 재유화형 EVA 분말수지 함량이 4%까지는 휨강도, 압축강도, 건조수축안정성 등 기초물성이 향상되는 것을 확인하였다. 하지만, 재유화형 EVA 분말수지 5%를 사용할 경우 물성이 크게 향상되지 못하거나 4% 대비 감소하는 것을 확인하였다. 투수계수 측정결과 8.30×10<SUP>-10</SUP>에서 5.50×10<SUP>-12</SUP>까지 저투수성을 발현하는 것을 확인하였다. The polymer liner and cover material were produced with an admixture of re-emulsification type ethylene vinyl acetate (EVA) powder resin to make the low water permeability mine liner and cover material. The purpose of this study is to improve the basic physical properties and water tightness by filling the space between cement and aggregate with EVA polymer film, which result in the improvement of waterproof performance. It was confirmed that basic properties such as strength and dry shrinkage stability were improved until the re-emulsification type EVA powder resin was mixed up to 4%. However, it was confirmed that the physical properties were not significantly improved when 5% of the re-emulsification type EVA powder resin was used, or decreased compared with the case of using 4% of that. As a result of the measurement of the permeability coefficient, the physical properties were improved from 8.30×10<SUP>-10</SUP> to 5.50×10<SUP>-12</SUP>.