• 한국대기환경학회지
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• 제21권6호
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• pp.573-583
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• 2005

Fugitive dust, which is emitted in the ambient air without first passing through a stack or duct designed to control flow, is frequently generated by means of wind erosion from storage yards at Pohang Steel Wokrs. The size distribution of fugitive dust is mostly in the range of coarse particulate which is deposited as soon as emitted and less harm to human health; however $20\%$ of fugitive dust contains PM 10 known as one of most harmful airborne pollutant. Consequently, effective control and reduction of fugitive dust is strongly requested by the local society, but it is not easy so far because the generation and dispersion of fugitive dust highly depends on meteorological conditions, and it being occurred for irregularity. This research presented a fugitive dust control system for each meteorological condition by providing statistical prediction data obtained from a statistical analysis on the probability of generating the threshold velocity at which the fugitive dust begins to occur, and the frequency occurring by season and by time of the wind direction that can generate atmospheric pollution when the dispersed dust spreads to adjacent residential areas. The research also built a fugitive dust detection system which monitors the weather conditions surrounding storage yards and the changes in air quality on a real-time basis and issues a warning message by identifying a situation where the fugitive dust disperses outside the site boundary line so that appropriate measures can be taken on a timely basis. Furthermore, in respect to the spraying of water to prevent the generation of fugitive dust from the storage piles at the storage yard, an advanced statistical meteorological analysis on the weather conditions in Pohang area and a case study of fugitive dust dispersion toward outside of working field during $2002\∼2003$ were carried out in order to decide an optimal water-spraying time and the number of spraying that can prevent the origin of fugitive dust emission. The results of this research are expected to create extremely significant effects in improving surrounding environment through actual reduction of the fugitive dust produced from the storage yard of Pohang Steel Works by providing a high-tech warning system capable of constantly monitoring the leakage of fugitive dust and water-spray guidance that can maximize the water-spraying effects.

• Progress in Superconductivity
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• 제10권1호
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• pp.55-59
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• 2008

A Superconductor Flywheel Energy Storage System(SFES) mainly consists of a pair of non-contacting High Temperature Superconductor(HTS) bearings that provide very low frictional losses, a composite flywheel with high energy storage density. The HTS bearings, which offer dynamic stability without active control, are the key technology that distinguishes the SFES from other flywheel energy storage devices, and great effort is being put into developing this technology. The Superconductor Journal Bearing(SJB) mainly consists of HTS bulks and a stator, which holds the HTS bulks and also acts as a cold head. Static properties of HTS bearings provide data to solve problems which may occur easily in a running system. Since stiffness to counter vibration is the main parameter in designing an HTS bearing system, we investigate SJB magnetic force through static properties between the Permanent Magnet(PM) and HTS. We measure stiffness in static condition and the results are used to determine the optimal number of HTS bulks for a 100kWh SFES.

• 전기화학회지
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• 제6권2호
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• pp.145-152
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• 2003

전해 캐패시터와 supercapacitor의 특성을 함께 가지는 하이브리드 캐패시터의 용량은 표면이 산화물로 피복된 양극에 의해서 좌우된다 본 연구에서는 고전압 하이브리드 슈퍼캐패시터의 제조를 위해 양극의 용량 최적화를 수행하였다. $40{\mu}m$의 입자경을 갖는 알루미늄 분말과 NaCl분말을 4:1의 무게비로 혼합하여 디스크 형태의 전극을 만들고 열처리를 하였다. 열처리 후 $50^{\circ}C$의 증류수에서 NaCl을 용해시켜 열처리 온도에 따른 용량과 저항을 비교하였다. 최적의 열처리 과정을 거친 후 electropolishing 및 화학처리, 1차 및 2차 에칭을 단계별로 행하였고 각각의 단계에서 최적의 조건을 조사하였다 각각의 단계에서의 용량과 저항은 ac impedance analyzer를 사용하여 측정하였으며 전극의 표면은 SEM을 이용하여 관찰하였다. 2차 에칭 후 내전압이 300V급인 전극으로 만들기 위하여 365V로 양극산화 시켰으며, 산화된 알루미늄 디스크 전극을 사용하여 단위 셀을 제조하여 주파수에 따른 용량과 저항 특성을 기존의 300V급 알루미늄 전해 캐패시터와 비교하였다.

• Journal of Pharmaceutical Investigation
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• 제8권4호
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• pp.23-36
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• 1978

Since the active center of digestive enzymetic preparations, while under storage, lose their activity and potency by the exposure to moisture, colorization, solidifying and other physical changes. It is more important than beautiful package form that protected packaging form from moisture to get a pharmaceutical safety preparations and to maintain a definite potency. Then, in order to get a desirable conditions of storage and packaging, we used shellac and $AEA^{\circledR}$ as a coating base, and blister package, foil and bottle container as a packaging material. Temperature were set on room temperature and $37^{\circ}C$, moisture was adjusted to 40% RH and 80 % RH as a accelerated conditions. Accelerated test was carried out 6 times. The results are as follows: 1) The effect of packaging conditions give great influence on the maintenace of the stable potency. 2) Best result was produced with bottle container package. 3) $AEA^{\circledR}$ is more useful than shellac as a coating base of prevention from moisture. 4) Absorption of moisture gave considerable effects on potency and it has a limited point. 5) Difference in potency between optimal and worst condition is 472 u/2T, and difference in effective period is about 44 months.

• 대한의생명과학회지
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• 제11권1호
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• pp.63-69
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• 2005

We investigated the changes of fibrinolytic and antioxidative activities of wild or cultivated Codonopsis lanceolata, which were packed in woven polypropylene (WP) film or low density polyethylene (LDPE) film and stored for 0, 15, and 30 days at refrigerated $(2\~4^{\circ}C)$ or room $(l8\~20^{\circ}C)$ temperature (So we have 16 samples, and wrote them as the abbreviated words such as W-WP-RE-15, W-WP-RO-15, W-LDPE-RE-15, W-LDPE-RO-15, W-WP-RE-30, W-WP-RO-30, W-LDPE-RE-30, W-LDPE-RO-30, C-WP-RE-15, C-WP-RO-15, C-LDPE-RE-15, C-LDPE-RO-15, C-WP-RE-30, C-WP-RO-30, C-LDPE-RE-30, C-LDPE-RO-30). Fibrinolytic activity of fresh Codonopsis lanceolata cultivated in the mountain or field were 0.8 unit (plasmin unit/ml) or 7.3 units, respectively. In descending order, the activities of wild Codonopsis lanceolata stored for 15 days were as followed; LDPE-RE (0.70 unit), WP-RO (0.52 unit), WP-RE (0.45 unit), and LDPE-RO (0.30 unit). After 30 days, fibrinolytic activities of them decreased to 0.47 unit (LDPE-RE), 0.28 unit (WP-RO), 0.21 unit (WP-RE), and 0.30 unit (LDPE-RO). Considering from the point of fibrinolytic activity, the optimal storage condition of wild Codonopsis lanceolata was packing with LDPE film and storing at $4^{\circ}C$. The change of fibrinolytic activities of Codonopsis lanceolata cultivated in the field revealed the similar trend as wild samples, but the fibrinolytic activities of 30 days-stored samples were maintained better than the wild Codonopsis lanceolata. Fibinolytic activity of wild Codonopsis lancealata was increased by heating for 5 min at $100^{\circ}C$ and decreased by addition of NaCl. Antioxidative activities of Codonopsis lanceolata were also compared from the electron donating activity. Fresh Codonopsis lanceolata had about $70\%$ of electron donating activity. Independent of cultivation area, electron donating activity dropped to $19\~74\%$ (wild Codonopsis lanceolata) and $27\~59\%$ (cultivated Codonopsis lanceolata) during 15 days storage. But after 30 days storage, we obtained the unexpected results, which meant that the activities were higher activities than 15 days-stored samples or even though the fresh samples. In general, Codonopsis lanceolata could maintain antioxidative activities most strongly with LDPE film and chilled condition.

• 한국농공학회지
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• 제37권3_4호
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• pp.34-47
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• 1995

It is experienced fact as a regular annual event that the structure to he designed on unreasonable flood for the agricultural structures including reservoirs have been brought not only loss of lives, but also enormous property damage. For the solution of this problem at issue, this study was conducted to develop an optimal runoff hydrograph model by comparison of the peak flows and time to peak between observed and simulated flows derived by linear time-invariant and linear time-variant models under the condition of having a short duration of heavy rainfall with uniform rainfall intensity at nine small watersheds which are within the range of 55.9 to 140.7 square kilometers in area in Han, Geum, Nagdong and Yeongsan Rivers. The results obtained through this study can be summarized as follows. 1. Storage constants and Gamma function arguments were calculated within the range of 1.2 to 6.42 and of 1.28 to 8.05 respectively by the moment method as the parameters for the analysis of runoff hydrograph based on linear time-invariant model. 2. Parameters for both linear time-invariant and linear time-variant models were calibrated with nine gaged watershed data, using a trial and error method. The resulting parameters including Gamma function argument, N and storage constant, K for linear time-invariant model were related statistically to watershed characteristic variables such as area, slope, length of main stream and the centroid length of the basin. 3. Average relative errors of the simulated peak discharge of calibrated runoff hydrographs by using linear time-variant and linear time-invariant models were shown to be 0.75 and 5.42 percent respectively to the peak of observed runoff hydrographs. Correlation coefficients for the statistical analysis in the same condition were shown to be 0.999 and 0.978 with a high significance respectively. Therefore, it can be concluded that the accuracy of a linear time-variant model is approaching more closely to the observed runoff hydrograph than that of a linear time-invariant model in the applied watersheds. 4. Average relative errors of the time to peak of calibrated runoff hydrographs by using linear time-variant and linear time-invariant models were shown to be 16.44 and 19.89 percent respectively to the time to peak of observed runoff hydrographs. Correlation coefficients in the same condition were also shown to be 0.999 and 0.886 with a high significance respectively. 5. It can be seen that the shape of simulated hydrograph based on a linear time- variant model is getting closer to the observed runoff hydrograph than that of a linear time-invariant model in the applied watersheds. 6. Two different models were verified with different rainfall-runoff events from data for the calibration by relative error and correlation analysis. Consequently, it can be generally concluded that verification results for the peak discharge and time to peak of simulated runoff hydrographs were in good agreement with those of calibrated runoff hydrographs.

• 한국수자원학회논문집
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• 제42권9호
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• pp.759-771
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• 2009

장거리 용수공급 시스템에서 전력비용은 전체 운영비용의 큰 부분을 차지한다. 본 연구는 시간단위의 펌프와 배수지 시스템의 최적 운영계획을 평가하기 위해 동적계획기법에 기초한 방법론을 제시하고 있다. 해석방법은 운영비용 최소화 관점에서 펌프용량 확대를 전제로 현재 가용 펌프의 효율적 운전과 전력요금체계, 시간별 용수수요 추이 그리고 배수지 특성과 송수관로의 제약조건 등을 고려하였다. 이를 위해 적용 가능한 시스템 운영목적과 제약조건이 제시되었고 개발된 방법은 수도권 광역상수도 양주계통의 2개 가압장과 5개 배수지를 대상으로 적용하였다. 적용결과는 펌프 확장의 경우 상당한 수준의 운전비용을 절감할 수 있는 것으로 나타났으며, 이와 같은 방법은 기존 시스템의 최적운영은 물론 생애주기 비용 최소화 측면에서 신규 용수공급 체계의 설계 등에 적절히 활용될 수 있다.

• 한국버섯학회지
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• 제10권4호
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• pp.224-235
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• 2012

최근 식용버섯에 대한 자실체의 아미노산 성분함량은 자료별로 수집하면 종류 및 성분함량에 있어서 그 차이가 크며, 성분에 대한 일정한 어떤 경향치를 확인하기 곤란한 상황이다. 버섯품종 및 저장 온도에 따른 영양성분의 손실을 비교 조사하고 그 기준을 정립하기 위한 기초자료 수집을 목적으로 팽이버섯 자실체 내의 아미노산을 함량을 HPLC로 분석 정량하여 버섯 자실체의 영양성분의 변화를 검토하고자 하였다. 수확후 시료에서 가장 높은 함량을 보인 성분은 cystein, arginine, gultamic acid, proline 등이었으나 품종 및 저장기간에 따라 많은 차이를 보인다. 저장온도별 분석결과에서는 $-1^{\circ}C$ 보다 $4^{\circ}C$에서 저장하는 것이 저장기간에 따른 성분손실이 적은 것으로 나타났다. 계통간에 저장기간에 따른 아미노산 종류별 함량에서 백색계열은 그 변화가 심하지 않았으나 갈색계통은 그 변화가 심하여, 백색 및 갈색 계통간의 차이가 크고, 계통내의 품종간에서도 그 차이가 있었다. 아미노산 함량은 일부 Proline등과 같이 증가하는 경우를 보이는 경우를 제외하고, 일정하지는 않으나 저장기간에 따라 감소하는 경향을 보이고 있다. 종합해보면 팽이버섯 자실체의 아미노산 함량은 계통, 품종, 저장기간 등에 따라 차이를 있는 것을 확인할 수 있었다.

• 디지털융복합연구
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• 제12권6호
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• pp.223-229
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• 2014

대용량의 지식베이스 시스템에서 유용한 정보를 추출하여 효율적인 의사결정을 수행하기 위해서는 정제된 특징추출이 필수적이고 중요한 부분이다. 러프집합이론에 있어서 최적의 리덕트의 추출과 효율적인 객체의 분류에 대한 문제점을 극복하고 자, 본 연구에서는 조건 및 결정속성의 효율적인 특징추출을 위한 러프엔트로피 기반 퀵리덕트 알고리듬을 제안한다. 제안된 알고리듬에 의해 유용한 특징을 추출하기 위한 조건부 정보엔트로피를 정의하여 중요한 특징들을 분류하는 과정을 기술한다. 또한 본 연구의 적용사례로써 실제로 UCI의 5개의 데이터에 적용하여 특징을 추출하는 시뮬레이션을 통하여 본 연구의 모델링이 기존의 방법과 비교결과, 제안된 방법이 효율성이 있음을 보인다.

• Ocean Systems Engineering
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• 제8권3호
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• pp.247-279
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• 2018

This study aims to investigate the behavioral characteristics of the LWSCR (lazy-wave steel catenary riser) for a turret-moored FPSO (Floating Production Storage Offloading) by using fully-coupled hull-mooring-riser dynamic simulation program in time domain. In particular, the effects of initial geometric profile on the global performance and structural behavior are investigated in depth to have an insight for optimal design. In this regard, a systematic parametric study with varying the initial curvature of sag and arch bend and initial position of touch down point (TDP) is conducted for 100-yr wind-wave-current (WWC) hurricane condition. The FPSO motions, riser dynamics, constituent structural stress results, accumulated fatigue damage of the LWSCR are presented and analyzed to draw a general trend of the relationship between the LWSCR geometric parameters and the resulting dynamic/structural performance. According to this study, the initial curvature of the sag and arch bend plays an important role in absorbing transferred platform motions, while the position of TDP mainly affects the change of static-stress level.