노동조합몰입의 영향요인에 관한 비교연구 : 생산직과 사무직 노조원의 몰입요인 비교를 중심으로

鄭然昻,具種權 中央大學校 經營硏究所 1997 經營學論集 Vol.23 No.1

고화제의 종류에 따른 중금속 슬러지의 고형화 특성 연구

정연구,이승환 金烏工科大學校 1999 論文集 Vol.20 No.-

The solidification technology is a process to convert hazardous wastes into waste form suitable for safe disposal with an improvement of the physical and handling characteristics of the waste. In this study, three kinds of synthetic heavy metal sludges including Cu, Cr and Pb, respectively, were solidified with a cement-based and a lime-based solidification process. In a cement-based process, fly ash and lime was mixed with cement as an additive. Fly ash was used as a pozzolonic agent in a lime-based process. The unconfined compressive strength of solidified material was measured to test structural rigidity. The solidified heavy metal sludge was crushed to 2∼9.5mm and leached under the acidic condition using 0.1N acetic acid for 24 hours. The leachability of Cu was significantly reduced when it was solidified with cement/lime process. The amount of leached Cu decreased with an increase of lime addition. The two cement-based processes were found to be effective in solidification of Cr sludge. The chromium concentration in leaching solution was maintained at low value in a wide range of pH, which is outstanding feature of solidified Cr sludge. Lead sludge retarded the hydration of cement and resulted in low compressive strength of solidified material compared with other heavy metal sludge. Lime addition alleviated this adverse effect of lead sludge in cement-based solidification process. However, lime-based process was found not to be effective in development of compressive strength and reduction of leachability of heavy metals from solidified materials.

슬러지 특성을 고려한 정수장 배출수 처리시설의 설계탁도 결정

정연구,김교억 금오공과대학교 산업기술개발연구원 2001 産業技術開發硏究 Vol.17 No.-

of these solid residuals depends on the raw water quality, dosage of chemicals used, performance of treatment process, methods of sludge removal and backwash frequency. One of the most difficult task in planning and designing a residuals treatment process is determining the amount of materials to be handled. Bansong water treatment plant were chosen as a model plant in this study and its raw water quality and sludge production were investigated. Turbidity of raw water fluctuated significantly with change of season. It went up to 400 NTU in rainy summer season while it was 10~20 NTU in the other seasons. The relative frequency distribution of turbidity was highly skewed to the right. The SS/turbidity ratio was about 0.9, which is smaller than 1.4 being used popularly in Korea. The weight of sludge produced during the high turbidity increased substantially and its settling property was also greatly i Most conventional water treatment plants produce two major residuals-residuals from the sedimentation basin and residuals from backwashing a filter. The quantity and quality mproved, resulting in production of highly concentrated sludge. These results indicated that the volume of sludge produced during high turbidity may be similar to that of average turbidity. As a result, it was proposed that the average turbidity of three years should be used as a design criteria to estimate the sludge production in planning and designing a sludge treatment plants.

산소소비속도를 이용한 퇴비화 미생물의 활성도 평가

정연구,김진수 금오공과대학교 산업기술개발연구원 2000 産業技術開發硏究 Vol.16 No.-

Composting reaction usually proceeds under the dynamic change of some operating conditions such as pH, temperature and ammonia content. The pH value is usually maintained at low level during the initial stage of reaction, resulted from the active decomposition of easily degradable organic materials. The low pH gradually goes up to 8.5~9.0 with a production of ammonia. Along with these changes of operating conditions, reaction temperature also increases to 60℃ or even higher. As pH and temperature increase, the fraction of free ammonia that is responsible for the microbial inhibition also increases. As a results, active production of ammonia could inhibit the microbial activity in composting reaction. We investigated the effects of ammonia on the microbial activity in compost using oxygen consumption rate. The microbial activity of compost was found to be decreased with an increase of ammonia content in compost regardless of water content and temperature. It was also found that water content and temperature had greater effects on the microbial activity than the ammonia content. Additionally, the cumulative amount of oxygen consumed in biological reaction was successfully simulated with a modified Gompertz equation developed in this study.

HB 방법을 이용한 Ku-Band MESFET Gate 혼합기 설계 및 제작에 관한 연구

金正根,具然健 弘益大學校 科學技術硏究所 1994 科學技術硏究論文集 Vol.5 No.-

In this paper, the key feature is that the performance of MESFET mixers predicts the results through the simulations and minimizes the errors after fabricated, which is based on the nonlinear/linear analysis technique. The FET mixers require for nonlinear and linear analysis. First in the nonlinear analysis, the voltage and current waveform of nonlinear elements under large-signal excitation condition is determined by a harmonic balance method, where the Newton-Raphson algorithm is used to solve the resulting nonlinear equation. The computer time is reduced with the simple jacobian matrix. Second, in the linear analysis, the conversion gain and input, output impedance of mixers can be easily obtained by frequency conversion matrix. The analysis is applied to FET mixers and the design technique is presented. Finally, in order to check experimentally the capability of the analysis, a Ku-band 10.75GHz LO, implemented on the teflon (εr=2.33) substrate with a mounted MESFET(KF1010).

설계강우의 시간적분포에 따른 첨두유출량 변화에 관한 연구

이정식,정연구,이재준 金烏工科大學校 1998 論文集 Vol.19 No.-

In this study the effect of temporal patterns of design rainfall on characteristics or runoff is examined using the correlation analysis between the rates of variation of hydrograph and rainfall charateristics. Peak discharge, time to peak, and peak rainfall intensity which are hydrograph and rainfall charateristics are obtained by applying four methods of temporal patterns of design rainfall to the analysis of rainfall-runoff through RRL model. The result of this study are as follows : 1) The rate of variation of peak rainfall intensity is affected by the duration of design rainfall, and the Keifer and Chu method among four methods of temporal patterns has the greatest effect on the rate of variation of those. 2) It is shown that maximum peak discharge is obtained at forward type in longer duration of design rainfall and centered type in shorter duration of design rainfall. 3) Generally time to peak delays with the progress from forward to backward type in the rate of variation of time to peak.

구미산업단지 대기중 휘발성유기화합물(VOCs)의 농도특성

최우건,배상호,박덕신,정연구,김태오 한국환경과학회 2004 한국환경과학회지 Vol.13 No.3

This study focuses on the measurement of airborne Volatile Organic Compounds (VOCs) in the Kumi electronic industrial complex during the time periods of August and September, 2002 and January and February, 2003. This study was based on the US-EPA method TO-14 while the VOCs were analyzed with GC/MSD. The toluene level revealed high concentration at all measurement sites. The areal rank of average concentrations of VOCs is as follows : industry l>industry2>urban>middle>residential. Concentrations of VOCs in Kumi electronic industrial ones were generally higher than at Yeochon and Ulsan industrial complexes. Dichloromethane and trichloroethylene, which are used as a cleaner in the process of electronic industries, were observed 4 to 8 times higher than those of other areas. Among the aromatic compounds, toluene showed the highest level, while the concentrations of dichloromethane and trichloroethylene were higher than those of other halogen compounds. In Kumi, toluene, trichloroethylene, and dichloromethane were confirmed as the major compounds of VOCs by this research.

Clinical implications of the newly defined concept of ventilator-associated events in trauma patients

( Tae Yeon Lee ),( Jeong Woo Oh ),( Min Koo Lee ),( Joong Suck Kim ),( Jeong Eun Sohn ),( Jeong Hwan Wi ) 대한외상학회 2022 大韓外傷學會誌 Vol.35 No.2

Purpose: Ventilator-associated pneumonia is the most common nosocomial infection in patients with mechanical ventilation. In 2013, the new concept of ventilator-associated events (VAEs) replaced the traditional concept of ventilator-associated pneumonia. We analyzed risk factors for VAE occurrence and in-hospital mortality in trauma patients who received mechanical ventilatory support. Methods: In this retrospective review, the study population comprised patients admitted to the Jeju Regional Trauma Center from January 2020 to January 2021. Data on demographics, injury characteristics, and clinical findings were collected from medical records. The subjects were categorized into VAE and no-VAE groups according to the Centers for Disease Control and Prevention/National Healthcare Safety Network VAE criteria. We identified risk factors for VAE occurrence and in-hospital mortality. Results: Among 491 trauma patients admitted to the trauma center, 73 patients who received ventilator care were analyzed. Patients with a chest Abbreviated Injury Scale (AIS) score ≥3 had a 4.7-fold higher VAE rate (odds ratio [OR], 4.73; 95% confidence interval [CI], 1.46-17.9), and those with a glomerular filtration rate (GFR) <75 mL/min/1.73 ㎡ had 4.1-fold higher odds of VAE occurrence (OR, 4.15; 95% CI, 1.32-14.1) and a nearly 4.2-fold higher risk for in-hospital mortality (OR, 4.19; 95% CI, 1.30-14.3). The median VAE-free duration of patients with chest AIS ≥3 was significantly shorter than that of patients with chest AIS <3 (P=0.013). Conclusions: Trauma patients with chest AIS ≥3 or GFR <75 mL/min/1.73 ㎡ on admission should be intensively monitored to detect at-risk patients for VAEs and modify the care plan accordingly. VAEs should be closely monitored to identify infections early and to achieve desirable results. We should also actively consider modalities to shorten mechanical ventilation in patients with chest AIS ≥3 to reduce VAE occurrence.

Comparison of Clinical Presentation between Adult Patients with the Pandemic Influenza A (H1N1) 2009 Infection and Those with Noninfluenza Acute Respiratory Illness (초)

Yun Jeong Jeong,Ji Yeon Lee,Yeon Joo Lee,Seo Yun Kim,Hyeon Kyoung Koo,Sung Soo Park,Byoung Jun Lee,Jong Sun Park,Deog Kyeom Kim,Hee Soon Chung,Chang Hoon Lee 대한결핵 및 호흡기학회 2010 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.110 No.-

퇴비화 공정의 1차 발효단체에서 질소성 물질의 거동 평가

정연구(Yeon-Koo Jeong),김진수(Jin-Soo Kim) 유기성자원학회 2000 유기물자원화 Vol.8 No.3

음식쓰레기,슬러지 등과 같이 C/N비가 낮은 폐기 물을 호기성으로 퇴비화하는 경우 질소 성분이 많이 손실될수 있으며, 이는 비료성분의 손실,악취를 비 롯한 환경오염 발생 등을 유발할 수 있다 본 연구에서는 퇴비화 공정에서 질소성 물질의 보존방법을 도출하기 위한 기초 연구로 음식쓰레기를 실험실 규모로 퇴비화하면서 일반적인 호기성 퇴비화 공정에서 일어나는 질소의 거동을 분석하였다. 음식쓰레기는 종이나 나무조각과 혼합하여 퇴비화하였으며, 질소성 물질의 거동을 평가하기 위해 퇴비시료에 포함된 암모니아, 산화성 질소, 유기성 질소를 측정하였다. 배가스로 손실되는 질소도 황산으로 흡수시켜 정량하였다. 퇴비화 반응의 활성화 여부가 유기성 질소의 무기화에 큰 영향을 미치는 것으로 조사되었다. 활성이 좋은 퇴비를 식종한 경우 반응 초기부터 유기성 질소의 무기화가 활발히 진행되어 많은 양의 질소가 손실된 반면 초기의 낮은 pH 기간이 길어지면 유기성 질소의 분해가 지연되는 것으로 나타났다. 암모니아 손실량은 주입된 공기량의 영향이 큰 것으로 판단되며, 암모니아 손실이 증가하면 퇴비의 암모니아 함량이 크게 감소하였다. 질소에 대한 물질수지 분석을 통하여 초기 질소의 28~38%가 암모니아로 전환되었으며 전환된 암모니아의 77~94%가 가스로 손실된것으로나타났다. Composting of N-rich wastes such as food waste and wastewater sludges can be associated loss of with subsrancial gaseous N, which means loss of an essential plant nutrient but may also lead to environmental pollution. We investigated the behavior of nitrogenous materials during the fìrst high-rate phase in composting of food waste. Air dried food waste was mixed with shredded waste paper or wood chip and reacted in a bench scale composcing reactor. Samples were analyzed for pH, ammonia, OJcidized nitrogen and organic nitrogen. The volatilized ammonia nitrogen was also analyzed using sulfuric acid as an absorbent solucion. Initial progress of composting reaccion greatly influenced the ammonifìcation of organic nitrogen. A well-balanced composting reaction with an addition of active compost as an inoculum resulted in the promoted mineralization of organic nitrogen and volatilization of ammonia. The prolongation of initiallow pH period delayed the production of ammonia. It was also found that nitrogen loss was highly dependent on the air flow supplied. With an increase in input air flow, the loss of nitrogen as an ammonia also increased, resulted in substantial reduction of ammonia content in compost. The conversion ratio of initial nitrogen into ammonia was in the range of28 to 38% and about 77 ~94%of the ammonia produced was escaped as a gas. Material balance on the nitrogenous materials was demonstrated to provide an information of importance on the behavior of nitrogen in composting reaction.