기능성 쌀 수요분석

조재환 한국농업정책학회 2005 농업경영정책연구 Vol.32 No.4

The objective of this paper is to find out the factors which influence to purchase the functional rice. The data used in demand modeling are characterized by the fact that the functional rice consumption is zero in the case of a lot of household during the survey period. Therefore, limited dependent variable models are used to determine factors influencing on functional rice demand. Of limited dependent variable models, tobit model is proved to provide a better representation of analysing functional rice purchase behavior. Results indicate the level of the perception and confidence on the functional rice, and the careful concern of the new rice products are significant determinants of consumption level with the household income variable. The results of this paper could be an important information for establishing the functional rice marketing strategy effectively.

구조적 흉요부/요부 만곡 청소년기 특발성 측만증에서 원위부 유합 범위를 결정하는데 있어서 동적 혹은 정적 기준의 신뢰도 비교

조재환,황창주,박재우,이동호,이춘성 대한척추외과학회 2019 대한척추외과학회지 Vol.26 No.4

Study Design: Retrospective comparative study. Objectives: To compare the reliability of 2 criteria to predict the radiological outcomes of corrective surgery in cases of adolescent idiopathic scoliosis (AIS) with structural thoracolumbar/lumbar (TL/L) curves. Summary of Literature Review: Distal fusion level selection in AIS with structural TL/L curves is debatable. Materials and Methods: This study included 131 AIS patients with structural TL/L curves who underwent corrective surgery in which distal fusion was stopped at L3. Whole-spine standing radiographs and bending radiographs were obtained preoperatively. The patients were divided into 2 groups according to their findings on bending radiographs (dynamic criterion) and by the last touching vertebra and the lower end vertebra (static criterion). Radiological outcomes were assessed by reviewing postoperative radiographs. Reliability tests were conducted to compare the predictability of radiological outcomes using these 2 methods. In addition, radiological parameters were compared between both criteria. Results: Among 131 patients, 25 showed radiologically poor outcomes (19.1%). The sensitivity of the dynamic and static criteria was 0.69 and 0.50, respectively. The specificity of each criterion was 0.49 and 0.64, respectively. Overall, the dynamic criterion showed superior reliability (p=0.03). However, no significant difference in radiological parameters could be found in a comparison of both criteria. Conclusions: Although the dynamic criterion was more sensitive for predicting poor radiological outcomes when stopping fusion at L3 in patients with structural TL/L curves, its specificity was lower than that of the static criterion. Thus, both dynamic and static criteria should be considered when selecting the distal fusion level in cases of AIS with structural TL/L curves. Key words: Adolescent idiopathic scoliosis, Double major curve, Distal fusion level, Lower instrumented vertebra 연구 계획: 후향적 비교 연구목적: 구조적 흉요부/요부 만곡 청소년기 특발성 측만증 환자 수술 후 방사선학적 결과를 예측하는 2가지 기준의 신뢰도를 비교하기 위함선행 연구문헌의 요약: 구조적 흉요부/요부 만곡 청소년기 특발성 측만증의 원위부 유합 부위 결정은 이견이 많음. 대상 및 방법: 원위 유합을 L3까지 수술한 구조적 흉요부/요부 만곡 청소년기 특발성 측만증 환자 131명을 대상으로 하였다. 수술전 전신 척추 기립 자세와 측부 굽힘 방사선 사진을 촬영하였다. 환자들은 측부 굽힘 사진 상의 기준(동적)과, Last touching vertebra와 lower end vertebra에 따른 기준(정적)에따라 분류하였고, 술후 방사선학적 결과에 따라 분석하였다. 두 기준에 따른 방사선학적 결과 예측의 신뢰도를 분석하였고, 여러 방사선학적 인자들의 차이를 분석하였다. 결과: 131명의 환자중 25명이 불량한 결과를 보였다(19.1%). 동적 기준과 정적 기준의 민감도는 각각 0.69와 0.50이었고, 특이도는 0.49와 0.64였다. 전반적으로는 동적 기준이 우월한 신뢰도를 보여주었다(p=0.03). 하지만, 두 기준에 따른 방사선학적 인자들의 차이는 없었다. 결론: L3에서 유합을 멈췄을 때 동적 기준이 더 불량한 예후를 예측하는데 민감했지만, 특이도는 정적 기준보다 낮았다. 구조적 흉요부/요부 만곡 청소년기 특발성 측만증 환자에서 원위 유합 범위 결정에 두 기준 모두를 고려하는 것이 좋을 것으로 생각된다. 약칭 제목: 구조적 흉요부/요부 만곡 청소년기 특발성 측만성 환자의 원위 유합 범위 결정

PVDF/PMMA 용액의 열가역적 겔화에 관한 연구

조재환,김정대 한국섬유공학회 1997 한국섬유공학회지 Vol.34 No.10

Thermoreversible gels of blends of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) in ${\gamma}$-butyrolactone solution were prepared, and the effects of the addition of amorphous PMMA to the solutions on gelation mechanism, sol-gel transition and gel morphology were investigated. Gels of PVDF/PMMA blends could be obtained when the weight percent of PVDF in the blend is 40% or lower, and the sol-gel transition temperature decreased with the increase of PMMA. The size of spherical gels observed by scanning electron microscopy was dependent on the gelation temperature and weight percent of PMMA. Gels prepared at the gelation temperature of 4$0^{\circ}C$ were the largest in size regardless of weight percent of PMMA, and the gels obtained from 80/20 PVDF/PMMA blend solution showed the largest size among the gels formed at 4$0^{\circ}C$. These phenomena were considered to be due to the competition of crystallization and liquid-liquid phase separation of solution. At low temperatures, gelation occurred dominantly due to crystallization. However, it is due to phase separation of the solution at high temperatures even though crystallization followed the gelation. This is consistant with the turbidity measurement results.

지역 농산물 공동브랜드의 TV 광고효과 분석 : 함안수박을 중심으로

조재환 한국농업경제학회 2010 農業經濟硏究 Vol.51 No.3

The purpose of this study is to evaluate the economic impacts of regional brand advertising through television. This article deals with estimation and testing of three type of different distributed lag models such as finite distributed lag model, polynomial distributed lag model, and exponential distributed lag model with an example given of sales and advertising data for a water melon produced in the Ham-An area in Korea. The results indicated that exponential distributed lag model more general than the frequently employed finite distributed lag model and polynomial distributed lag model is shown to be consistent with the evidence. The evidence leads to the conclusion that the major effect of TV advertising on sales rapidly declines after two months even if the carryover effect of television advertising on sales lasts for four months. In addition, an estimated benefit-cost ratio was 26.1 indicating that every won invested into TV advertising cost returned \26.1 back in terms of agricultural income

살충제 파동으로 인한 수요감소가 계란가격에 미치는 영향

조재환,이상학,박종현,이한성 경상국립대학교 농업생명과학연구원 2019 농업생명과학연구 Vol.53 No.6

In August 2017, Korean government announced that pesticide ingredients had been found in domestic eggs, and it caused to decrease the egg consumption. Bird influenza reported in January 2017 induced egg farmers to increase the number of chickens and it resulted in oversupply in the egg market. These two incidents brought about egg price decline at that time in Korea. The objective of this article is to estimate the impacts of consumption decrease and oversupply on the egg price. The number of news report was used to represent the consumption decrease, and the egg production was used to represent the oversupply. It is assumed that consumption decrease and oversupply have carry-over effects on the price. Basically, the finite distributed lag model was used for the estimation, and the polynomial distributed lag model was added to minimize the multicollinearity problem. Producing area prices and retail prices were used for analysis and compared with each other. The results of estimation shows that producing area prices are responding more sensitively and quickly to the independent variables than retail prices in the short term, but the degrees are decreasing in the long term. Therefore, introduction of marketing order need to be considered to stabilize the egg price. 본 연구는 살충제 파동이라는 부정적인 언론보도가 계란 시장가격 하락에 미치는 동태적 과정을 실증적으로 분석한다. 이를 위하여 다항식시차분포모형을 이용하여 살충제 파동에 관한 부정적 언론보도의 영향이 산지와 소비지에서 어느 정도 상이하게 나타나는지, 영향이 언제까지 지속될 것인지, 영향의 강도가 시간대별로 어느 정도 상이한지를 계측하고, 또한 공급물량 증가에 따른 영향에 비해 살충제 파동의 영향이 어느 정도 되는지를 추정하고자 하였다. 분석결과, 산지가격모형과 소매가격모형 모두 공급량은 산지가격과 반비례관계인 것으로 나타났다. 산지가격모형의 가격신축성 계수가 소매가격모형의 그것보다 약 2.46배 큰 것으로나타나 계란 공급량의 변화에 대해 산지가격이 소비지가격보다 상대적으로 민감하게 반응한다는 것을 알 수있다. 따라서 계란 생산자단체 중심으로 한 공급량 조정이 더 유효한 대응책일 것으로 판단된다. 살충제 파동에 따른 영향을 나타내는 시차분포가중치의 합을 비교해 본 결과, 산지의 경우가 소매지의 경우에 비해 약2.73배 정도 크게 나타났는데, 이는 살충제 파동의 영향이 소비지보다 산지에서 더 크다는 것을 말해준다. 산란계 사육두수의 지속적인 증가에 따른 계란의 시장가격 하락으로 인한 피해는 소비지보다 산지가 더 크므로 생산자단체 중심으로 가격 안정을 꾀할 수 있는 유통명령제 도입이 시급하다.

Structure - Property relationships of the Wholly Aromatic Copolyesters with Phenylhydroquinone Moiety

조재환,윤병숙,손태원 한국고분자학회 1990 한국고분자학회 학술대회 연구논문 초록집 Vol.1990 No.10

Structure and Physical Property of the Blends of Ultra-high Molecular Weight Polyethylene

조재환,국윤환,황윤언,Jo, Jae-Hwan,Guk, Yun-Hwan,Hwang, Yun-Eon The Korean Fiber Society 1989 한국섬유공학회지 Vol.26 No.2

Gel films were prepared from the mixtures of ultra-high molecular weight polyethylene(UHME PE) and high density polyethylene (HDPE) in a decalin solution. To investigate the formation of mixed crystals in the blends, i.e.cocrystallization, melting behaviors of the gel films and the slowly cooled films from melt were analyzed by differential scanning calorimetry. The slowly cooled films from melt as well as gel films showed the single melting peaks and this was ascribed to the formation of mixed crystals. The heat of fusion of the slowly cooled films from melt was nearly linear to the weight percent of UHMW PE and HDPE but gel films showed a minimum value. However, no significant lattice changes were found in the X-ray diffraction of gel films. The tensile moduli of gel films decreased with the increase of weight percent of HDPE and the yield stresses were almost constant in the intermediate weight percent of UHMW PE and HDPE.

폴리비닐리덴플루오라이드-테트라플루오로에틸렌과 폴리비닐 리덴플루오라이드-헥사플로오로아세톤의 블렌드의 압전성

조재환,김상용,궁전청,Jo, Jae-Hwan,Kim, Sang-Yong,Gung, Jeon-Cheong The Korean Fiber Society 1989 한국섬유공학회지 Vol.26 No.2

Poly(vinylidenefluoride-tetrafluoroethylene), P(VDF-TFE)and poly(vinylidenefluoride-hexafluoroacetone), P(VDF-HFA) were blended, both of which were crystalline polymers. The crystal structures of the blends were investigated using X-ray diffraction. The samples containing the rich P(VDF-TEE) showed the crystal structure of only the polar phase, whereas those containing the rich P(VDF-HFA) showed the mixed crystal structure of $\alpha$ and $\beta$ phases. The piezoelectric properties of the blends were measured to investigate the origin of piezoelectricity and the mechanism of dipole reorientation. The piezoelectricity may be originated from the residual polarization and the internal strain of the samples. The 180$^{\circ}$rotation of dipoles was supported by the fact that the measured value of the maximum polarization agrees with the calculated value using the frozen dipole model.

연신조건이 저온에서의 PET 필라멘트사의 점탄성적 성질에 미치는 영향

조재환,조원호,김상용,Jo, Jae-Hwan,Jo, Won-Ho,Kim, Sang-Yong 한국섬유공학회 1981 한국섬유공학회지 Vol.18 No.1

Dynamic mechanical measurements were made in order to investigate effects of the drawing conditions on the viscoelastic properties of PET filament yarns at low temperatures(-100$^{\circ}$C∼-0$^{\circ}$C). The tan$\delta$-temperature relations of the Maxwell and the Zener model were theoretically plotted and compared with the experimental data. It was shown that the experimental results nearly coincided with the Maxwell model at temperatures below the ${\beta}$ peak and with the Zener model in the neighbor of the ${\beta}$ peak. Maximum tan$\delta$ at the ${\beta}$ peak decreased with the increase of the drawing temperature but was not affected by the draw ratio. On the other hand maximum tan$\delta$ temperature at the ${\beta}$ peak was not significantly affected by the drawing temperature and the draw ratio.

새로운 Polyarylethersulfone 의 합성과 그 특성

조재환,이철주,손태원 한국고분자학회 1989 한국고분자학회 학술대회 연구논문 초록집 Vol.1989 No.10