D-limonene included in citrus fruits is obtainable to extract essential oil as well as separate the oil ingredient. Soxhlet extraction, a type of SDE (Simultaneous steam Distillation and solvent Extraction), was used to extract limonene from tangerine peel. HPLC analysis was performed to quantify extracted d-limonene by using reversed-phase HPLC column. Results of HPLC analysis showed that the optimal extraction time was 2 hours in any solvent, and the extracted amounts of d-limonene in tangerine peel (per g tangerine peel) were 7.77 mg, 0.49 mg, and 0.28 mg in ethyl alcohol, nhexane, and ether. Because yield was the highest in using ethyl alcohol as a solvent, polarity is stronger factor to effect on yield of extraction than boiling point.

Aragonite is an important dimorph of calcium carbonate, industrially and biologically. However, aragonite is so thermodynamically unstable that it is difficult to understand its formation mechanism. A continuous microfluidic system was employed, in which crystallization was induced only by diffusion in a micron-scale channel. Calcium carbonate (CaCO 3 ) formed by liquid-liquid reaction and magnesium ions (Mg 2+ ) were used as additives. To assess the influence of Mg 2+ concentration, the Mg 2+ /Ca 2+ molar ratio was set to 1, 3, and 5. Laminar streams flowed in the detection channel with different concentration gradients. The initial crystallization time (t I.C ) increased exponentially and the density of crystals decreased as the Mg 2+ ion concentration increased. Following transformation of all particles into snowman or sphere shapes, they became spinose sphere-shaped crystals, which was the final form in this study.

− Crystallization of CaCO 3 is practiced on a polymethylsiloxane (PDMS) -based microfluidic system. Liquid-liquid reaction was investigated by mixing calcium chloride (CaCl 2 ) and sodium carbonate (Na 2 CO 3 ) solution to crystallize CaCO 3 . Aspartic acid (Asp) was added to investigate the morphology change such as vaterite and calcite. Suitable ratio of Na 2 CO 3 and CaCl 2 was searched for initial seed formation. Christmas tree model was used as microfluidic device to form concentration gradient of Na 2 CO 3 and CaCl 2 . After observing microfluidic channel by using optical microscope, we found that seeds of CaCO 3 were formed under the condition that the ratio of Na 2 CO 3 and CaCl 2 was 2:1. Morphology of crystals were also observed as CaCO 3 crystals grow. When Asp was added, vaterite crystal was more frequently found in two morphologies (vaterite and calcite) and seed formation and crystal growth were inhibited.

요 약양이온교환 고성능액체크로마토그래피에서 라이소자임을 분석하고, 실험결과인 크로마토그램을 통해 모멘트 분석을 수행하였다. 용리 인산완충용액은 1.0, 0.75, 0.5 M의 소금을 포함하였다. 실험변수는 유량, 용리 완충용액중 소금 농 도, 시료의 농도로 하였다. General rate (GR) model을 도입하여 1차와 2차 모멘트를 해석하였다.Abstract − The moment analysis of lysozyme was implemented using chromatograms that were obtained from weak cation exchange column in high performance liquid chromatography system. Three elution sodium phosphate buffers containing 1.0, 0.75, 0.5 M sodium chloride were used. Experiments were conducted by varying flow rate, elution sodium chloride concentration, and lysozyme solute concentration. The general rate (GR) model was employed to calculate the first moment and the second moment. By plotting L/u 0 vs. (μ 1 -t 0 )/(1-ε e )(1-ε i )] equilibrium constants (K) were obtained from first moment analysis. Intra-particle diffusivity was obtained from theoretical plate number data. Based on the results of moment analysis, van Deemter plots were drawn in order to investigate the contributions of H ax , H f , and H d to total Height Equivalent to a Theoretical Plate (HETP, H total ). The effect of intra-particle diffusion (H d ) was the most dominant factor contributing to HETP while external mass transfer (H f ) was negligible factor.

요 약고성능액체크로마토그래피(high-performance liquid chromatography, HPLC)에서 C18(octadecyl silica, ODS) 칼럼에서 고리형 아데노신 일인산(cyclic adenosine monophosphate, cAMP)의 크로마토그램을 얻은 후, 모멘트 분석을 수행하였 다. 일반속도 모델(general rate model, GR model)을 기반으로 first absolute moment와 second central moment를 계산 하였다. 모멘트 분석의 중요한 세 가지 계수인 분자확산계수(molecular diffusivity, D m ), 외부물질전달계수(external mass transfer coefficient, k f ), 입자내부확산계수(intra-particle diffusivity, D e )는 각각 Wilke-Chang 식, Wilson-Geankoplis 식을 이용하고 이론단수(theoretical plate number) 식과 van Deemter 식을 비교하여 계산하였다. 실험은 각각 세 가지의 이동상 조성, 용질 농도, 유량 조건에서 수행하였다. Van Deemter 그래프를 그려 모멘트 분석결과를 정성적으로 정리 했으며, 이론단 상당높이(height equivalent to a theoretical plate, HETP,Abstract − The moment analysis of cyclic adenosine monophosphate (cAMP) was performed using chromatograms that were obtained with the pulse input method from an octadecyl silica (ODS) high-performance liquid chromatography (HPLC) column. The general rate (GR) model was employed to calculate the first absolute moment and the second central moment. Three important coefficients for moment analysis, which are molecular diffusivity (D m ), external mass transfer coefficient (k f ), and intra-particle diffusivity (D e ), were estimated by the Wilke-Chang equation, Wilson-Geankoplis equation, and comparing van Deemter equation to theoretical plate number equation, respectively. Experiments were conducted by various conditions of flow rates, methanol volume ratio of the mobile phase, and solute concentration. After the moment analysis, results were organized by van Deemter plots. Also van Deemter coefficients were compared each other to effect H ax , H f , and H d on height equivalent to a theoretical plate (HETP, H total ). The value of intraparticle diffusion (H d ) was the primary factor which makes for HETP whereas external mass transfer (H f ) was disregardable factor.