• 한국조리학회지
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• 제12권4호
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• pp.299-319
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• 2006

The purpose of this study was to investigate the changes of hardness and microstructure of Dongchimi cooked with various sources of sugar(xylitol, xylose, sugar, pear juice). It was fermented at $10^{\circ}C$ for 60 days. The changes of pH in Dongchimi used different kinds of sugar decreased in all samples during the fermentation period, and then showed a slow decrease after 12 days of fermentation. The total acidity of Dongchimi using xylitol arrived slowly at the best tasting condition($0.3\sim0.4$ point) compared with other conditions. The changes of salt content were showed high as compared with other test conditions in 0 day, the day of fermentation. At the early stage of fermentation, the changes of turbidity of Dongchimi using sugar, pear juice were showed high as compared with those of Dongchimi using xylitol, xylose for $5\sim15$ days of fermentation. The maximum cutting force of Chinese radish Dongchimi showed the highest value among al at the 25 th day of ripening and then decreased gradually. The maximum cutting force of Dongchimi using sugar showed the lowest. The calcium and magnesium contents of Dongchimi juice and Chinese radish Dongchimi juice using xylitol were observed high at the early stage of fermentation and showed the highest value during the fermentation period. The microstructure showed disintegration appearance of middle lamella and cell wall during the fermentation period.

• 대한소아치과학회지
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• 제28권1호
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• pp.32-44
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• 2001

Er : YAG 레이저의 상아질 삭제효과와 이에 따른 온도변화를 평가하고자 발거된 소구치와 대구치로 상아세관내 조직액과 치수내압을 유지할 수 있는 상아질 시편을 제작하고 $2.94{\mu}m$의 pulsed Er : YAG 레이저(SDL-300EN, 삼성전자, 한국)를 handpiece형의 전달계를 이용한 비접촉식 방법으로 조사세기, pulse repetition rate, 조사시간, 물 분사여부 등의 조사조건을 달리하여 상아질 면에 조사하고 이때의 삭제량과 상아질 두께에 따른 온도변화, 그리고 삭제형태를 조사, 분석하여 다음과 같은 결과를 얻었다. 1. 레이저 조사세기와 pulse repetition rate가 클수록, 그리고 조사시간이 길수록 삭제량이 증가되었다(P<0.05). 그러나 5Hz의 pulse repetition rate에서는 조사시간에 따른 삭제량의 차이가 크지 않았다. 2. 삭제된 와동은 비교적 변연부가 명확하고 깨끗하였으며 와동의 바닥은 원추형이였으며 부드러웠다. 조사세기와 pulse repetition rate가 클수록, 그리고 조사시간이 길수록 와동의 상부 직경이 넓었으며 150mJ, 5Hz, 5sec에서는 와동변연부에 약간의 crack이 관찰되었다. 3. 레이저 조사세기와 pulse repetition rate가 클수록, 그리고 조사시간이 길수록 상아질의 온도가 더 많이 상승하였으며 시편의 두께가 두꺼울수록 온도상승이 적었다(P<0.05). 4. 물을 분사하며 레이저를 조사할 경우 물을 분사하지 않은 경우에 비해 온도상승이 매우 감소되었다(P<0.05). 이상의 결과를 종합해 볼 때 Er : YAG 레이저를 상아질에 조사할 경우 와동의 형태가 명확하고 물을 분사할 경우 온도상승이 많이 유발되지 않으므로써 삭제력이 좋고 치수에 유해작용이 없는 것으로 생각된다. 향후 임상에서 치질을 제거하는데 효율적으로 이용되기 위해서는 더욱 크고 이에 따른 온도상승을 최소로 할 수 있는 조사 시스템 및 방법에 대한 연구가 계속적으로 이루어져야 할 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권2호
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• pp.279-282
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• 2002

Twenty six male Hanwoo (Korean cattle) carcasses were measured for pH, temperature and instrumental color changes of loins during 24 h post-mortem carcass chilling at $4^{\circ}C$ in the cooler. The average internal temperature of loins was about $5^{\circ}C$ after 24 h of chilling, and with the exclusion of those with an ultimate pH>6.0 (dark-cutters), the average pH value was 5.5. When all carcasses were considered for the partial correlation coefficient between color and pH, with the temperature effect excluded, CIE $L^*$, $a^*$ and $b^*$ seemed to be affected significantly by pH during chilling process (p<0.001). However, when carcasses with dark-cutting condition were excluded, the correlation coefficients were much lower. In contrast, when the partial correlation coefficients between color and temperature, excluding the effect of pH on them, were analyzed, the relationship between color and temperature did not change much after values of DFD (dark, firm, dry) beef were excluded. The results suggested that the known interrelationship of color and pH in chilled beef loins be mainly due to the influence of temperature on pH and color.

• Journal of Biosystems Engineering
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• 제4권1호
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• pp.1-23
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• 1979

The use of barley seeder attached to rotary tiller in the rural area has a significant meaning not only for the solution of labor peak season, but also for the increase of land utilization efficiency. The facts that presently being used barley seeders are all based on the mechanical principles of the reverse rotation, center drive and are all using forward rotating tine, which is used to be easily and heavily worn out when it rotates reversely, raise problem of recommending them to rural area in Korea. Therefore, the main objective of the study was to develop new type of rotary tine attachable to barley seeders. To attain the objective the following approaches were applied. (1) The kinematic analysis of reverse rotating barley seeders. (2) The studies on the soil bin and artificial soil. (3) The comparative experiment on the power requirement of prototype tine. The results obtained from the studies are summarized as follow: 1. The kinematic analysis of barley seeder attached to rotary tiller: The following results were obtained from the kinematic analysis for deriving general formulae of the motion and velocity characterizing the rotary tine of barley seeders presently being used by farmers. a) The position vector (P) of edge point (P) in the rotary tine of reverse rotating, center drive was obtained by the following formula. $$P=(vt+Rcos wt)i+Rsin wt j+ \{ Rcos \theta r sin \alpha cos (wt- \beta +\theta r) +Rsin \theta r sin \alpha sin (wt-\beta + \theta r) \} lk $$ b) The velocity of edge point $(P^')$ of reverse rotating, center drive rotary tine was obtained by the following formula. $$(P^')=(V-wR sin wt)i+(w\cdot Rcoswt)j + \{ -w\cdot Rcos \theta r\cdot sin \alpha \cdot sin (wt-\beta +\theta r) + w\cdot Rsin \theta r\cdot sin \alpha \cdot cos (wt- \beta + \theta r \} k $$ c) In order to reduce the power requirement of rotary tine, the angle between holder and edge point was desired to be reduced. d) In order to reduce the power requirement, the edge point of rotary tine should be moved from the angle at the begining of cutting to center line of machine, and the additional cutting width should be also reduced. 2. The studies on the soil bin and artificial soil: In order to measure the power requirement of various cutting tines under the same physical condition of soil, the indoor experiments Viere conducted by filling soil bin with artificially made soil similar to the common paddy soil and the results were as follows: a) When the rolling frequencies$(x)$ of the artificial soil were increased, the densIty$(Y)$ was also increased as follows: $$y=1.073200 +0.070780x - 0.002263x^2 (g/cm^3)$$ b) The absolute hardness $(Y)$ of soil had following relationship with the rolling frequencies$(x)$ and were increased as the rolling frequencies were increased. $$Y=37.74 - \frac {0.64 + 0.17x-0. 0054x^2} {(3.36-0.17x + 0.0054x^2)^3} (kg/cm^3)$$ c) The density of soil had significant effect on the cohesion and angle of internal friction of soil. For instance, the soil with density of 1.6 to 1.75 had equivalent density of sandy loam soil with 29.5% of natural soil moisture content. d) The coefficient of kinetiic friction of iron plate on artificial soil was 0.31 to 0.41 and was comparable with that of the natural soil. e) When the pulling speed of soil bin was the 2nd forward speed of power tiller, the rpm of driving shaft of rotary was similar to that of power tiller, soil bin apparatus is indicating the good indoor tester. 3. The comparative experiment on the power requirement of prototype tine of reverse rotating rotary: According to the preliminary test of rotary tine developed with various degrees of angle between holder and edge pcint due to the kinematic analysis, comparative test between prototype rotary tine with $30 ^\circ $ and $10 ^\circ$ of it and presently being used rotary tine was carried out 2nd the results were as follows: a) The total cutting torque was low when the angle between holder and edge point was reduced. b) $\theta r$ (angle between holder and edge point) of rotary tine seemed to be one: of the factors maximizing the increase of torque. c) As the angle between holder and edge point ($\theta r$) of rotary tine was $30 ^\circ $ rather than $45 ^\circ $, the angle of rotation during cutting soil was reduced and the total cutting torque was accordingly reduced about 10%, and the reduction efficiency of total cutting torque was low when the angle between holder and edge point ($\theta r$) of rotary tine was $10 ^\circ $, which indicates that the proper angle between holder and edge point of rotary tine should be larger than $10 ^\circ $ and smaller than $30 ^\circ $ . From above results, it could be concluded that the use of the prototype rotary tine which reduced the angle between holder and edge point to $30 ^\circ $, insted of $45 ^\circ $, is disirable not only decreasing the power requirements, but also increasing the durabie hour of it. Also forward researches are needed, WIlich determine the optimum tilted angle of rotary brocket, and rearrangement of the rotary tine on the rotary boss.

• 한국초지조사료학회지
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• 제5권2호
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• pp.111-115
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• 1985

본(本) 시험(試驗)은 예취시기(刈取時期)를 달리하여 조제(調製)된 건초(乾草)를 이용(利用)하여 예취시기(刈取時期)와 섭취량(攝取量)이 소화율(消化率)에 미치는 영향에 대하여 검토(檢討)하였다. 목초(牧草)는 6월(月) 4일(日)(영양생장기(榮養生長期))과 6월(月)30일(日)(출수기(出穗期))에 예취(刈取)된 1 번초(番草)로 건초(乾草)를 조제(調製)하였으며 이 건초(乾草)는 제한급여(制限給與)와 수준(水準)으로 급여(給與)하였다. 그 결과(結果)를 요약(要約)하면 다음과 같다 1. 예취시기(刈取時期)가 지연(遲延)됨에 따라 조단백질(粗蛋白質) 및 조지방함량(粗脂肪含量)은 감소(減少)하였고, 섬유질(纖維質) 및 lignin함량(含量)은 증가(增加)하였다. 2. 조기예취건초구(早期刈取乾草區)와 만기예취건초구(晩期刈取乾草區)의 건물섭취량(乾物攝取量)은 각각(各各) $82g/W_{kg}^{0.75}$과 $68g/W_{kg}^{0.75$이였다. 3. 조기예취건초구(早期刈取乾草區)에서 제한급여(制限給與)와 자유채식간(自由採食間)의 건물소화율(乾物消化率)에서는 유의차(有意差)가 없었으며, 배분상태(排糞狀態)를 고려(考慮)하지 않은 무제한급여(無制限給與)에서는 현저하게 감소하였다. 그리고 조단백질(粗蛋白質), 유기물(有機物) 및 섬유질소화율(纖維質消化率)에서도 유의차(有意差)는 없었으나 자유채식(自由採食)했을 때가 감소(減少)하는 경향을 보였다. 4. 만기예취건초구(晩期刈取乾草區)의 경우 조단백질소화율(粗蛋白質消化率)을 제외한 전성분(全成分)의 소화율(消化率)이 섭취량(攝取量)의 증가(增加)에 따라 유의(有意)하게 감소(減少)하였다. (P<0.05 혹은 P<0.01) 5. 조기예취건초구(早期刈取乾草區) 와 만기예취건초구간(晩期刈取乾草區間)의 소화율(消化率)을 비교하면 1%수준(水準)의 유의차(有意差)가 있었다.

• 한국분말재료학회지
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• 제6권1호
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• pp.88-95
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• 1999

The purpose of this study is to investigate the manufacturing feasibility of WC-Co milling inserts via Powder Injection Molding (PIM) process. WC-Co is used in a wide variety of cutting tools due to its high hardness, stiffness, compressive strength and wear resistance properties. WC-Co parts for a high stress application were conventionally produced by the press and sinter method, which were Iimited to 2 dimensional shapes. Manufacturing WC-Co parts for a high stress application by PIM implies that tool efficiency can be highly improved due to increased freedom is design. P30 grade WC powder (WC-Co-TiC-TaC system) was mixed with RIST-5B133 binder and injection molded into milling inserts (Taegu Tech. Model WCMX 06T 308). The mean grain size of the powder was about 0.8$\mu$m. Injection molded specimens were debound by solvent extraction and thermal degradation method at various conditions. The specimens were sintered at 140$0^{\circ}C$ for 1 hr in vacuum. Carbon content, weight loss, dimensional change, and macro defects of the specimen were carefully monitored at each stage of the PIM process. PIMed WC-Co milling inserts reached 100% full density after sinteing. Its mechanical properties and micro-structures were comparable with the press and sintered milling insert. Carbon content of the sintered WC-Co insert was mainly determained by the atmosphere of thermal debinding. By controlling powder loading and injection molding condition, dimensional accuracy could be obtained within 0.4%. We confirm that PIM can not only be an alternative manufacturing method for WC-Co parts economically but also provide a design freedom for more effieient cutting tools.

• 한국초지조사료학회지
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• 제14권4호
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• pp.271-280
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• 1994

본 실험은 전차 확대대어 가는 유휴 논토양에 Reed canarygrass를 재배하였을 때 , 예취빈도와 무기태 질소시비가 건물수량에 미치는 영향을 조사하여, Reed canarygrass의 잠재생산성의 증대를 위한 경제적 이고도 합리적인 예취빈도와 지로시비수준을 추정하고자 하였다. 그 결과를 요약하면 다음과 같다. 1. 예취빈도에 EKfms 예취번초의 상대수량은 3회와 4회 예취구에서 2번초, 5회 예취구에서는 3번초에서 연간 건물수량의 43.1, 34.0 및 34.1%를 나타내어, 다른 예취번초에 의하여 가장 높은 상대수량을 기록하였다. 2. 모든 예취구에서 질소시비수준이 증가함에 따라 연간 건물수량이 증가하였으나, 무기태 질소는 예취빈도멸 30kg/ha으로 증시하였을 때 무질소시비구에 비해 3회 4회 5회 예취에서 각각2.7ton, 3.3ton 및 3.4ton/ha의 가장 큰 건물수량의 증가를 나타내었다.(p<0.05).4. 질소시비에 따른 전물생산효율(kg DM/kg N)은 3, 4회 및 5회 예취구의 30kg/ha 수준에서 2937kg, 27.2kg 및 22.8kg의 가장 높은 건물을 생산하였으나, 그 이상의 질소시비수준에서의 건물생산효율은 저하되었다. 전질소량(kg TN/kg N)에 있어서도 예취빈도별 30kg/ha(4회와 5회 예취구)와 60kg/ha 수준(3회 예취구)에서 각각 0.45kg, 0.48kg 및 0.46kg의 높은 전질소량을 나타내었으나 그 이상의 질소시비수준에서 전질소량은 저하되었다. 5, 경제적 시비수준의 범위는 3회 예취구에서 119.2~243.3kg/ha, 4회 예취구에서 253.4~295.4kg/ha 그리고 5회 예취구에서 302.2~361.2kg/ha의 범위였다. 6. 본 실험의 조건에서 논토양에서 재배되고 있는 Reed canarygrass의 잠재생산성을 최대한으로 발휘할 수 있는 예취빈도는 연간 3회로써, 질소이용효율이 높았고, 경제적 시비수준은 200~240kg/ha에서 15~16ton/ha정도의 경제적 한계수량을 얻었고, 400kg/ha 미만의 한계시비수준에서 17ton/ha의 최대건물수량을 얻을 수 있었다.

• 자원리싸이클링
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• 제30권1호
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• pp.60-65
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• 2021

타이타늄 터닝 스크랩을 재활용하기 위해서는 표면에 남아있는 절삭유나 기타 오염물을 제거해야할 필요가 있다. 본 연구에서는 초음파 침지-스팀의 복합 세척 공정을 활용하여 타이타늄 스크랩을 세척하고, 건조 조건을 달리하여 절삭유를 제거하는 실험을 진행하였다. 또한 절삭유 제거 메커니즘 확인을 위한 접촉각 측정을 통해 타이타늄 터닝 스크랩의 침지 용액 최적 농도를 확인하였다. 피로인산나트륨 용액에 침지 세척 시 50℃에서 절삭유 내 탄소 제거율이 가장 높았으며, 스팀 세척-초음파 침지-스팀 세척 순으로 진행하는 것이 초음파 침지 후 스팀 세척을 실시하는 것보다 탄소 함량이 낮은 것을 확인했다. 타이타늄 스크랩의 TGA 분석을 통해 산화 및 절삭유의 분해 거동을 조사하고 고온 건조에 적용하였다. 건조 후 탄소와 산소 함량을 고려 시 200℃에서 2시간 건조를 하는 것이 최적의 조건임을 확인하였다.

• 한국기계가공학회지
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• 제2권1호
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• pp.63-68
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• 2003

The aspherical lenses are used as objective lens of optical pickup. To examine the design factor the sample product is made before manufacturing of injection mould of lens. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, the roam spindle speed, the depth of cut, the feedrate are found. The demanded surface roughness 100m Ra, aspherical form error $0.5{\mu}m$ P-V for aspherical lens of optical data storage device are satisfied.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.891-894
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• 1997

The asphericals lenses are used as objective lens of optical pickup. To examine the design factor the sample product is made before manufacturing of injection mould of lens. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, he main spindle sped, the depth of cut, the feedrate are found. The demanded surface roughness 10nm Ra, aspherical form error 0.5${\mu}{\textrm}{m}$ P-V for aspherical lens of optical data storage device are satisfied.