AE 신호를 이용한 회전형 압축기의 이상상태 감시

이감규,정지홍,김전하,강명창,김정석 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.5

The compressor has one of important roles in refrigeration cycle and it determines refrigeration efficiency and quality. This paper aims to monitor rotary compressors for room air conditioners by using Acoustic Emission(AE) technique. The reliability of rotary compressors has been evaluated through visual inspection on them after long term test. This paper describes methods for acquisition and processing AE raw signal to monitor the state of rotary compressor. A detecting method of abnormal compressor in real time is suggested and special-purpose monitoring system which can be applied to automatic manufacturing line is developed using one-chip microprocessor at low cost.

Effects of Polyelectrolyte Dosage, Kaoline Particles and pH on Flocculation of Humic Acid by Cationic Polyelectrolytes

Kam, Sang-Kyu,Kim, Dae-Kyoung,Lee, Min-Gyu 한국환경과학회 2003 한국환경과학회지 Vol.12 No.8

Using a simple continuous optical technique, coupled with measurements of zeta potential, the effects of polyelectrolyte dosage, kaoline particles and pH on flocculation of humic acid by several cationic polyelelctrolytes, have been examined. The charge density of a polyelectolyte is important in determining the optimum dosage and in the removal of humic acid. The optimum dosage is less for the polyelectrolytes of higher charge density and is the same regardless of the presence of kaoline particles of different turbidity. At the dosage, the removal of humic acid is higher for the polyelectrolytes of higher charge density and the zeta potential of humic acid approaches to near zero. With increasing pH of humic acid, the optimum dosage increases and the flocculation index value obtained at the dosage decreases in the following sequences: pH 7> pH 5> pH 9, regardless of polyelectrolytes.

Flocculation Characteristics of Kaoline Suspensions in Water by Cationic Polyelectrolytes

Kam, Sang-Kyu,Kim, Dae-Kyoung,Moon, Chang-Seong,Ko, Byung-Churl,Lee, Min-Gyu 한국환경과학회 2002 한국환경과학회지 Vol.11 No.2

Using a simple continuous optical technique, coupled with measurements of zeta potential, the flocculation characteristics of kaoline suspensions of different content(15, 35 and 55 NTU) by several cationic polyelectrolytes, has been examined. The optimum mixing is obtained under a constant stirring of 200 rpm, differntly from a general flocculation test. The charge density of a polyelectrolyte is important in determining the optimum dosage and in the removal of kaoline particles. The optimum dosage is less for the polyelectrolye of higher charge density and is the same regardless of kaoline content. At the dosage, the removal of kaoline particles is higher for the polyelectrolye of higher charge density and zeta potential of kaoline particles reaches to near zero. The rate of adsorption and flocculation rate have been found to be affected by charge density and molecular weight of a polyelelctrolyte and the content of kaoline particles.

제주도 한림항내 표층퇴적물 중의 부틸주석화합물의 분포

감상규,김현정,허철구,최영찬,이민규 한국환경과학회 2003 한국환경과학회지 Vol.12 No.7

Butyltin compounds (BTs), namely tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT), were measured in surface sediments collected in 2001 inside Hallim Harbor where a lot of shipping occurs as one of major harbors of Jeju Island, in order to evaluate their distribution. BTs were detected in surface sediments of all stations and their concentrations were comparable to those in surface sediments of other sites of domestic and foreign countries. The main species among BTs was MBT, although there was a little difference with a survey site. No correlations were obtained between organic matter or particles size of surface sediments and total BTs, indicating that these factors did not affect on the distribution of BTs. It was estimated that more complex factors including BTs loads and surrounding sedimentary environments, affected on the distribution of BTs. The high correlations between BTs indicated that DBT and MBT were mainly degraded from TBT based on antifouling paints of vessel etc. and other sources, such as DBT and MBT, could be ignored. The butyltin degradation indexes ([DBT] + [MBT]/[TBT]) were in the range of 1.5~3.3 (mean 2.5), indicating that the parent compound, TBT, were inflowed into the surface sediments a long years ago and degraded.

Biosorption of Heavy Metal lons by Biomass of Marine Brown Algae in Cheju using Their Immobilization Techniques: Biosorption of Copper by Undaria pinnatifida

Kam Sang-Kyu,Lee Min-Gyu The Korean Environmental Sciences Society 1997 Environmental sciences Vol.1 No.2

The biosorption performances of copper were investigated by the immobilized biomass of nonliving marine brown algae Undaria pinnatifida by each of the Ca-alginate method(Ca-ALG), Ba-alginate method(Ba-ALG), polyethylene glycol method(PEG), and carrageenan method (CARR). The copper removal performance increased but the copper uptake decreased as the biomass amount was increased. However, the copper uptake by the immobilized biomass increased with increasing initial copper concentration. Among the immobilization methods, the copper uptake decreased in the following sequence: Ca-ALG > Ba-ALG > PEG > CARR. The pattern of copper uptake by the immobilized biomass fitted the Langmuir isotherm better than the Freundlich isotherm. Desorption of deposited copper with 0.05 ~0.5M HCI, resulted in no changes of the copper uptake capacity of the immobilized biomass by the immobilization methods except for PEG, through five subsequent biosorption/desorption cycles. There was no damage to the immobilized biomass which retained its macroscopic appearance in repeated copper uptake/elution cycles.

수중의 Pyrene, Chrysene 및 Benzo[a]pyrene의 광분해(Ⅱ)

감상규,김지용,주창식,이민규 한국환경과학회 2003 한국환경과학회지 Vol.12 No.7

The photodegradations of pyrene, chrysene and benzo[a]pyrene that were similar in structure among polycyclic aromatic hydrocarbons (PAHs) were investigated with a low-pressure mercury lamp(the wavelength of 253.7 ㎚ and UV output of 1.35x10^(-3) J/s). The optimum concentrations of TiO₂ and H₂O₂ on the photodegradation of pyrene, chrysene and benzo[a]pyrene were 1 g/L and 1.5 x 10^(-3) M, respectively. By these optimum concentrations, their rates increased with increasing the concentration of TiO₂ and H₂O₂ because the amounts of OH radical formed increased, but for the higher concentrations than the optimum, their rates decreased with increasing those concentrations because the white turbidity phenomena occurs in case of TiO₂ and H₂O₂ acts as an OH radical inhibitor. The photodegradation rates among the photodegradation processes such as UV, UV/TiO₂, UV/H₂O₂, and UV/H₂O₂/TiO₂ decreased in the following sequences: UV/H₂O₂/TiO₂> UV/H₂O₂> UV/TiO₂> UV.

황토로부터 합성한 제올라이트에 의한 Cd(Ⅱ) 및 Cu(Ⅱ) 흡착특성

감상규,홍정연,허철구,이민규 한국환경과학회 2003 한국환경과학회지 Vol.12 No.7

Various kinds of zeolites, such as analcime (ANA), cancrinite (CAN), Na-P1 and sodalite octahydrate (SOD) could be synthesized from Hwangto by hydrothermal reaction in a high-pressure vessel. The adsorption characteristics of Cu(Ⅱ) and Cd(Ⅱ) by Hwangto and its synthetic zeolites were investigated using the chemical and electrochemical surface parameters of these adsorbents. The heavy metal adsorptivity among the adsorbents decreased in the following sequences: Na-P1 > SOD > ANA > CAN > Hwangto. This sequence was the same with the values of surface site density (Ns) of these adsorbents and was correlated inversely with the values of pHpzc (pH of the point of zero charge) and the values of Ka2(int) (intrinsic surface deprotonation constant) of the adsorbents for synthetic zeolites, i.e., the adsorbents with higher values of Ns and with lower values of pHpzc and Ka₂(int) for synthetic zeolites showed higher heavy metal adsorptivity. With increasing pH, the heavy metal adsorptivity increased greatly between pHpzc and pH 6 or 7 because of the steep increase of negatively charged sites for synthetic zeolites, but for Hwangto, it increased broadly because of slow increase of negatively charged sites based on its lower surface sites.

합성 Goethite에 의한 인산이온, 황산이온 및 구리이온의 혼합용액에서의 흡착특성

감상규,이동환,이민규 한국환경과학회 2003 한국환경과학회지 Vol.12 No.10

Adsorption on goethite of individual component from a solution containing phosphate, sulfate, or copper ion was investigated. Competitive adsorption in the binary and ternary solution systems composed of phosphate, sulfate. and copper ions was also investigated. In competitive adsorption systems with phosphate and sulfate ions. the presence of phosphate ion reduced the adsorption of sulfate ion largely. On the other hand. the presence of sulfate ion caused only a small decrease in phosphate adsorption. This result suggests that phosphate ion is a stronger competitor for adsorption on goethite than sulfate ion. which is consistent with the higher affinity of phosphate for the surface compared to sulfate ion. Compared to the results from single-sorbate systems, adsorption of copper ion in the binary system of sulfate ion and copper ion was found to be enhanced in the presence of sulfate ion. Addition of sulfate ion to the binary system of copper ion and phosphate ion resulted in a small enhancement in copper sorption. This result implies that the presence of sulfate ion promotes adsorption of the ternary complex FeOHCuSO₄. The adsorption isotherms could be well described by the Langmuir adsorption equation.

석탄회로 합성한 제올라이트에 의한 Sr(Ⅱ) 및 Cs(Ⅰ) 이온의 제거 특성

감상규,이동환,문명준,이민규 한국환경과학회 2003 한국환경과학회지 Vol.12 No.10

The adsorption behaviors of strontium and cesium ions on fly ash, natural zeolites, and zeolites synthesized from fly ash were investigated. The zeolites synthesized from fly ash had greater adsorption capabilities for strontium and cesium ions than the original fly ash and natural zeolites. The maximum adsorption capacity of synthetic zeolite for strontium and cesium ions was 100 and 154 ㎎/g, respectively. It was found that the Freundlich isotherm model could fit the adsorption isotherm. The distribution coefficients (K_(d)) for strontium and cesium ions were also calculated from the adsorption isotherm data. The distribution coefficients decreased with increasing equilibrium concentration of strontium and cesium ions in solution. By studying the removal of cesium and strontium ions in the presence of calcium. magnesium, sodium. potassium. sulfate, nitrate, nitrite, and EDTA (in the range of 0.01 - 5 mM) it was found that these coexistence ions competed for the same adsorption sites with strontium and cesium ions.

Comparison of Flocculation-Spectrophotometry and Streaming Current Detector Method to the Control of Flocculants for the Removal of Humic Acid

Kam Sang-Kyu,An Lee-Sun,Lee Min-Gyu The Korean Environmental Sciences Society 1997 Environmental sciences Vol.1 No.2

Flocculation-spectrophotometry and streaming current detector(SCD) method were investigated and compared in order to determine the optimum dosages of synthetic cationic polymers of different charge density and molecular mass for the removal of humic acid. The optimum dosage for each of the polymers was determined with the dosage at which the lowest absorbance of humic acid was shown for the former and was determined with the dosage required during charge neutralization of humic acid for the latter. It was in good agreement between both methods and there is a strong inverse correlation between the optimum dosage and charge density of the polymers, with highly charged polymer giving the lowest optimum dosage, pointing out the importance the charge neutralization. By flocculation-spectrophotometry, it was found that the absorbance of humic acid with the amount of each of the polymers dosed, changes sharply for polymers of high charge density, but changes rather broadly for polymers of low and middle charge density. Both methods showed that a stoichiometric correlation exists between the optimum dosage of each of the cationic polymers and the negatively charged humic acid.