In this work, ultra-fine calcium oxide (CaO) powder derived from eggshells is used as the starting material to synthesize mineral trioxide aggregate (MTA). The prepared CaO powder is confirmed to have an average particle size of 500 nm. MTAs are synthesized with three types of fine CaO-based powders, namely, tricalcium silicate (C3S), dicalcium silicate (C2S), and tricalcium aluminate (C3A). The synthesis behavior of C3S, C2S and C3A with ultra-fine CaO powder and the effects of C3A content and curing time on the properties of MTA are investigated. The characteristics of the synthesized MTA powders are examined by X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), and a universal testing machine (UTM). The microstructure and compressive strength characteristics of the synthesized MTA powders are strongly dependent on the C3A wt.% and curing time. Furthermore, MTA with 5 wt.% C3A is found to increase the compressive strength and shorten the curing time.

이 연구는 파각란 선별기 도입을 비용 편익분석 목적으로 수행되었다. 계란 파각란 선별기를 도입할 때의 총수입과 총비용 평가액의 추정결과는 다음과 같다. 총비용의 경우 구입가격, 고정비용 및 유동비용의 합계로 나타내었고, 할인율에 따라 5%, 10%일 때 각각 232,904천원과 242,904천원으로 산정되었다. 계란 파각란 선별기 평가액은 할인율에 따라 228,543천원(할인율 5%인 경우)과 218,543천원(할인율 10%인 경우)으로 추정되었다(Table 6). 파각란 선별기 기술가치에 대한 평가는 B/C비율, 순현재가치(NPV), 내부수익율(IRR)의 값으로 판단되었고, 내부수익율 IRR의 값은 가정했던 할인율보다 훨씬 높게 나타났고, 순현재가치도 0보다 큰 값으로 나타났으며, B/C비율도 1.0 이상으로 나타나 경제적 타당성을 가지는 것으로 판단되었다(Table 7).

Calcium phosphate powders were successfully synthesized by using re-cycled eggshell and phosphoric acid. The crystallization behavior and powder morphologies of the synthesized powders were dependent on the starting condition of the eggshell, the mixing ratio and method of the eggshell and phosphoric acid, and calcination temperature. In general, -tricalcium phosphate was stably synthesized at about 90 for 1h at each proper mixing ratio. And, the synthesized powders showed the similar microstructures to the morphology of original eggshell with uniform particle sizes. In this study, the calcium phosphate powders were synthesized with eggshell in various processing method. And their unique microstructures obtained from the eggshell were also. observed. The crystalline developments and microstructures of the synthesized powders were examined by X-ray diffractometer and scanning electron microscopy

The purpose of this study was to investigate the egg freshness and eggshell characteristics of old laying hens by adding sea urchin shell powder to the feed of such hens to achieve the objectives continuously pursued by environmental management, such as business profitability and waste resource utilization. A total of 90 Hy-Line Brown layers (66 weeks of age) were randomly divided into 2 treatments with 3 replicates, each of which consisted of 15 older layers, for 4 weeks. These treatments included a control (i.e., 0%) and 2% sea urchin shell powder. The 2% supplementation of sea urchin shell powder increased the Haugh unit (HU) at 2 and 4 weeks and eggshell strength at 4 wks compared to the controls (p<0.05). The HU at 0 weeks, eggshell thickness from 0 through 3 weeks, and eggshell strength at 0 and 2 weeks were not different between treatments (p>0.05). These results suggest that the addition of 2% sea urchin powder to the feed of laying hens improves egg freshness and eggshell strength in old laying hens.

This study was conducted to investigate the effects of dietary supplementation of various types of fermented red ginseng marc with red koji to laying hens on eggshell and egg yolk quality characteristics. A total of 240 Hy-line Brown laying hens (40 wk of age) were randomly allotted to 24 pens (6 replicates per treatment and 10 laying hens per replicate). Experimental diets consisted of 4 treatments containing basal diet (control), 1% fermented red ginseng marc powder with red koji, 1% fermented red ginseng marc pelleted with red koji and 1% fermented red ginseng marc coated with red koji. During the 8-wk feeding trial, there were no significant differences in eggshell strength, eggshell thickness and eggshell color among the treatments, except for eggshell strength at 4 and 8 wk and eggshell thickness at 0 wk. In addition, no differences in egg yolk color and egg yolk index were found for all treatments throughout the 8-wk feeding period, except for egg yolk color at 0 wk. Thus, using various types of fermented red ginseng marc with red koji to laying hens did not improve eggshell and egg yolk quality characteristics.

We tried to develope a desulfurization sorbent using eggshell for recycling, practicability, and economic development. The calcination character of the eggshell was examined by thermal gravimetric analysis and qualitative-quantitative character by X-ray diffractometer(XRD) and scanning electron microscope(SEM). The calcination was occurred easily in the case of eggshell and its form was changed from calcite(CaCO_3) to lime(CaO). The grain and pore sizes of the calcined sample after base-treatment were larger and more crystallic. The adsorption ability of the eggshell was two- to six-times in the calcination temperature more than in the grain size. Therefore, the eggshell was thought to be usable as the desulfurization sorbent.