In most of sintered metal powder compacts, the sintered density distribution is controlled to be as high and uniform as possible to ensure the required mechanical properties. In general, the density distribution in the compacts is not uniform and not easy to measure. In the present study, a method for measuring the density distribution was developed, based on the indentation force equation by which the hardness and the relative density were related. The indentation force equation, expressed as a function of strength constant, workhardening coefficient and relative density, was obtained by finite element analysis of rigid-ball indentation on sintered powder metal compacts. The present method was verified by comparing the predicted density distribution in the sintered Fe-0.5%C-2%Cu compacts with that obtained by experiments, in which the density distribution was directly measured by machining the compacts from the outer surface progressively.

Powder forging is a combined technology of powder metallurgy and precision hot forging. Recently, the technology is developing rapidly because of its economic merits, especially in automotive part manufacturing. In the present study, the finite element technique was developed to predict density variation during P/M forging and the technique was applied to analysis of forging of a P/M connecting rod. Although deformation mode of the connecting rod was quite complex, several sections were selected and analyzed under an assumption of asymmetric or plane strain deformation. It was found that some modifications were necessary on the cross section of the beam portion. Therefore, the cross section was modified repeatedly until a satisfactory result of the analysis was obtained. On the other hand, no modifications were necessary in the ring and the pin portions. It is anticipated that the developed technique can be used to optimize preform design and manufacturing processes in P/M forging, which are highly critical to produce successful products in practice.

본 연구는 코끼리 흑마늘의 분말화를 위해 추출액과 말토덱스트린을 비율 별로 첨가한 후 분말을 제조하였으며, 제조 및 저장 조건 별로 품질 특성을 비교 분석하는데 목적을 두었다. 분말의 용해도는 90.87-96.93%으로 5:5 처리구에서 가장 높은 값을 보였으며 색깔의 경우 말토덱스트린 함량이 증가할수록 명도는 감소하였으나 적색도와 황색도는 증가하였다. 입도는 7:3 처리구를 제외하고 말토덱스트린 함량에 비례하여 증가하는 추세를 보였으며, 분산성은 0.54-0.63 범위에서 나타났다. 포화 염용액으로 다른 상대습도를 조성하여 25, 35℃에서 분말을 각각 저장했을 때 평형 수분함량은 4:6에서 가장 낮게 나타났다. 그리고 단분자층 수분함량을 산출하기 위해 GAB 식과 BET 식을 이용하였으며 모든 조건에서 0.943-0.997로 높은 R2값을 보였다. 여러 처리구 중 4:6 처리구가 단분자층 수분함량이 가장 낮았으며 다른 처리구들은 온도나 적용 식에 따라 다른 추세를 보였다. 또한 등온 흡습 모델의 적합성을 확인하기 위해 Caurie, Halsey, Kuhn, Oswin, Mizrahi 식을 사용하였는데, 그 중 Halsey, Kuhn 식이 높은 R2 값과 낮은 편차를 보여 적합성을 나타내었다.

Functional compounds including flavonoids, anthocyanins, polyphneols and antioxidants were extracted from blue honeysuckle (Lonicera caerulea L.) using highly efficient microwave-assisted extraction. And extraction process was modeled and optimized according to response surface methodology (RSM). The independent variables (Xn) were ethanol concentration (X1: 0, 25, 50, 75, 100%), irradiation time (X2: 1, 3, 5, 7, 9 min), and microwave power (X3: 60, 120, 180, 240, 300 W). Dependent variables (Yn) were total flavonoid contents (Y1), total anthocyanin contents (Y2), total polyphenol contents (Y3) and antioxidant activity (Y4). Four-dimensional response surface plots were generated based on the fitted second-order polynomial models to get optimal conditions. Estimated optimal conditions for 4 responses were ethanol concentration of 54-72%, irradiation time of 7.1-7.6 min, and microwave power of 243-251 W. Ridge analysis predicted the maximal responses of total flavonoid content, total anthocyanin content, total polyphenol content and antioxidant activity were 38.00 mg RE/g, 6.80 mg CGE/g, 14.90 mg GAE/g, 89.10%, respectively. Verification experiment was carried out at predicted optimal conditions and experimental values for total flavonoid content, total anthocyanin content, total polyphenol content and antioxidant activity were 38.10 mg RE/g, 6.72 mg CGE/g, 14.91 mg GAE/g and 89.13%, respectively. No significant difference was observed between predicted and experimental values, indicating good fitness of fitted model and successful application of RSM.

This study investigated quality change of ginseng depending on far-infrared (FIR) drying methods. The ginseng was cut into 2 mm slices and measured moisture content (MC), color, total polyphenol content (TPC), total flavonoid content (TFC) and DPPH radical scavenging activity (DPPH). The color values (L, a, and b) were decreased after far-infrared (FIR) drying. As increase in drying time, color was changed. Considering quality parameters including MC, TPC, TFC, and DPPH, the optimum condition for drying was set at 65℃ for 60 min. Furthermore, we compared color and functional compounds depending on drying process including FIR, freeze-, vacuum, and hot-air drying. The color values of ginseng were decreased when dried using vacuum and hot-air. While the color values of ginseng were increased after freeze drying. Comparison with another drying method, FIR drying presented the highest color difference. FIR and vacuum-dried ginseng indicate higher contents of TPC and TFC than freeze- and hot air-dried ginseng. And hot-air-dried ginseng present the highest DPPH when compared to another drying methods. On the other hand, freeze dried ginseng show the lowest TPC, TFC, and DPPH.

꾸지뽕 열매는 미생물에 의한 오염과 물러짐으로 저장기간이 짧고 유통이 어렵다는 단점이 있다. 농산물에 적용할 수 있는 선도 유지 및 가공법은 여러 방법이 있지만 본 연구에서는 실질적으로 농민들이 적용할 수 있는 블랜칭 처리방법과 열풍 건조법에 대해 연구하였다. 먼저 블랜칭 처리 시간별로 꾸지뽕의 생균수를 측정하여 블랜칭 처리 시간이 증가할수록 미생물이 점차적으로 감소하는 것을 확인할 수 있었다. 그리고 블랜칭 처리 시간 및 건조 조건에 따른 건조 추세를 비교한 결과, 40℃에서 건조 시 무처리구 보다 블랜칭 처리구가 더 빠른 수분 감소 효과를 나타내었다. 하지만 건조 온도가 증가할수록 무처리구와 블랜칭 처리구 간의 건조 추세 차이는 점점 줄어드는 것을 확인하였다. 최종적으로 블랜칭 및 열풍건조의 최적 조건을 도출하기 위해 반응표면 분석법을 이용하였다. 조건에 따른 total polyphenol content, total flavonoid content, DPPH radical scavenging activity, 색차(ΔE)의 예측값은 각각 8.62 mg GAE/g, 56.65 mg RE/g, 40.26%, 11.69의 수치를 나타냈다. 최적 범위 내 임의의 조건 즉, 240 sec 블랜칭 처리 시간, 60℃ 건조 온도, 24 h 건조 시간에서 실험값은 10.06 mg GAE/g, 49 mg RE/g. 44.99%, 10.53을 나타냈으며 예측값과 실험값은 유사한 값을 보였다.

Background: In this study, microwave extraction was used, which is an effective method to extract useful bioactive substances as it requires low quantities of solvent and short time periods. The aim of this study was to determine the optimal extraction conditions for Agrimonia pilosa Ledeb. Methods and Results: The independent variables were ethanol concentration, microwave power, and extraction time, each of which had five levels. The dependent variables were total polyphenol and total flavonoid content, and DPPH radical scavenging activity. To determine the optimal extraction conditions for bioactive compounds, a response surface methodology was employed. Contour maps were generated from polynomial equations. The optimal conditions were then assumed by superimposing these contour maps. Based on the resulting graph, the optimal microwave extraction conditions for Agrimonia pilosa Ledeb were determined as 42 - 48% ethanol concentration, 240 - 280W microwave power, and 13 - 20 min of extraction time. Conclusions: Ethanol concentration had a significant effect on microwave extraction, in terms of total polyphenol and total flavonoid content, as well as DPPH radical scavenging activity. Microwave power and extraction time influenced the total polyphenol content, but not the total flavonoid content or the DPPH radical scavenging activity.

본 연구는 전통적으로 방부 또는 살균효과가 있어 떡 등에 첨가되거나 저장 및 포장에 이용되었던 자생식물 15종 21건에 대하여 데하이드로초산(sodium dehydroacetate), 소르빈산(sorbic acid), 안식향산(benzoic acid), 파라옥시안 식향산메틸(methyl p-hydroxybenzoate), 파라옥시안식향산에틸(ethyl p-hydroxybenzoate), 파라옥시안식향산프로필(propyl p-hydroxybenzoate), 파라옥시안식향산이소프로필(isopropyl p-hydroxybenzoate), 파라옥시안식향산이소부틸(isobutyl p-hydroxybenzoate), 파라옥시안식향산부틸(butyl p-hydroxybenzoate), 프로피온산(propionic acid)의 함유량을 분석하였다. 솔잎, 망개잎, 대나무잎 등 15종에 대한 천연유래 보존료 함유량을 조사한 결과 솔잎, 대나무잎, 칡잎, 모시잎, 쑥, 잣나무잎 등 6종에서 안식향산, 소르빈산, 프로피온산을 확인할 수 있었다. 안식향산은 대나무잎, 모시잎, 솔잎, 쑥, 칡잎, 잣나무잎에서 8.201~21.839 mg/kg, 소르빈산은 대나무잎과 칡잎에서 5.630~24.995 mg/kg, 프로피온산은 모시잎에서 61.324~62.726 mg/kg이 검출되었다. 조사 식물 중 망개잎, 토란잎, 조릿대, 연잎, 원추리, 구절초, 떡갈나무잎, 산초잎, 감잎 등 9종에서는 천연보존성분이 검출되지 않았다.

2005년 3월부터 10월까지 과채류 152건을 대상으로 아황산염류의 자연함유량과 인위적인 사용실태를 비교하기 위하여 모니어-윌리암스 변법을 사용하여 이산화황의 함유량을 분석하였다. 가공하지 않은 14품목 42건에 대한 이산화황 분석결과 평균검출범위는 이었으며, 각 품목별 평균으로는 무가 8.97 mg/kg으로 가장 높았고 양파가 8.04 mg/kg 순으로 조사되었다. 가공한 23품목 110 건에 대한 이산화황 평균분석결과 검출범위는 이었으며,