• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.6
• /
• pp.369-373
• /
• 2008

Special concern has been given to the elevated arsenic content in soils because of its high mobility and toxicity. Layered double hydroxide (LDH) which has a high anionic exchange capacity is another potential anion adsorbent for toxic anions such as arsenic, chromate and selenium etc. The uptake of arsenate from aqueous solutions by the calcined Mg-Al LDH has been investigated. The sorption capacity was about 530 mmol/kg. Sorption isotherm was defined as L-type in which arsenate was removed by LDH through anion uptake reaction. Arsenate sorption by the calcined Mg-Al LDH was occurred by reconstruction of LDH's framework. Competitive adsorption revealed that Mg-Al LDH had higher selectivity for arsenate than for sulfate. These results strongly suggest that calcined Mg-Al LDH has a promising potential for efficient removal of toxic metal oxides like arsenates from aqueous environments.

• Journal of the Korean Geosynthetics Society
• /
• v.12 no.3
• /
• pp.87-94
• /
• 2013

As sediment contamination problems have recently been raised in Korea, the need for technologies to remove contaminants in sediments has increased. Contaminated sediments in Korea has been annually dredged and treated using processes of coagulation/flocculation, sedimentation on barges, dewatered and dried at prepared site, and then disposed at a landfill site, which is very costly, and only a limited landfill space available in Korea. Contaminants in media containing a high percentage of silt and clay sized particles, typically, are strongly adsorbed on the particles and difficult to remove. Particle separation processes that separate the fine clay and silt particles from the coarser sand and gravel and concentrate the contaminants into a smaller volume of sediment that can be further treated of disposed of, are very effective in the post step processes. In this study are to test the feasibility of treating dredged sediments using a hydrocyclone process, and to estimate design parameters for a pilot scale test. A hydrocyclone was operated to separate larger particles from the sediments. It was found that the particle separation was greatly affected by the solid contents and inlet pressure in the hydrocyclone.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.22 no.3
• /
• pp.53-59
• /
• 2014

In this study, the sewage sludge dryer is installed before and after dehydration of the sludge and aqueous phase composition, the heavy metal content, and measurement and analysis were investigated. The removal efficiency of water content of sewage sludge was about 95.7% in the sewage sludge dryer. The removal efficiency of water content for primary dryer was designed for 35% of primary drying, secondary drying to remove the water content to 10%, but as the measurement revealed that 20.8% of primary drying, the second dryer 3.3% a better effect to the actual operation respectively. Before the installation of the sewage sludge dryer, the content of heavy metal was as follows, Cu:352~614 ppm, Hg: 1.3~1.44ppm, Cd : 1.1~1.86ppm, Pb : 17.25~ 28.93 ppm, As : 1ppm. And after the installation of the sewage sludge dryer, the content of heavy metal changed to as follows, Cu : 340~350 ppm, Hg : 0 ppm, Cd : 0~0.021 ppm, Pb : 0 ppm, As : 0~0.043 ppm which is Also below the legal limits. Also, the sewage sludge dryer produce 1/4 of the sewage sludge into dried sludge.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.6
• /
• pp.1405-1410
• /
• 2018

The Ringer's Solution used in medical institutions is one of the injections helpful for recovering the body condition from fever or dehydration by supplying the water to the body. The medical staffs frequently check the amount of Ringer's Solution prescribed for the relevant patient to check the time for replacing the Ringer's Solution. However, currently, many nurses experience the excessive workload because of the insufficient workforce and lots of workload assigned to each of the nurses; so the they cannot provide the high-quality medical services to patients and guardians. In order to solve this problem, this thesis designed and realized the Ringer's Solution replacement time control system through the non-contacting sensor, IoT device using WiFi, and OCS interlock. Thus, this study is expected to be able to efficiently operate the Ringer's Solution replacement work and also to provide the high-quality medical service to patients and guardians by automatically notifying the timing of Ringer's Solution replacement to medical staffs, and omitting the inefficient intermediate step in the past.

• Membrane Journal
• /
• v.33 no.6
• /
• pp.305-314
• /
• 2023

Various methods for removing by-products from chemical reactions are being studied to improve yield of catalytic reaction. Since the water is predominantly generated as a by-product in industrially significant reactions, it is necessary to develop the technology that can reliably remove water over a wide range of temperatures. Although several strategies using absorbents and additional dehydration reactions, have been proposed, they have limitations due to the issues such as additional energy and time consuming steps and sustainability of conversion. Membrane technology, which offers advantages such as easy operation, installation, and low maintenance costs, proves to be a promising approach for enhancing the efficiency of catalysts in various catalytic reactions. Therefore, this review discusses the removal of by-products using membranes and the associated benefits in this context.

• Journal of the Korean Institute of Gas
• /
• v.21 no.2
• /
• pp.1-9
• /
• 2017

Enhanced coalbed methane recovery (ECBM), as injecting $CO_2$ or $N_2$ into the coalbed methane (CBM) reservoir for increasing methane recovery, takes center stage in these days. ECBM makes a better recovery than the conventional production method, it called dewatering process. However the characteristics of injection gas affect to methane recovery, thus analysis on the mixed ratio of injection gas should be required. In this study, CBM reservoir model was built to estimate the methane recovery of ECBM method by different mixed ratio of injection gas. Additionally, to consider the characteristics of injection gas such as carbon captured storage, nitrogen re-injection, etc. economic analysis was performed. The results showed that ECBM cases produced methane almost twice as much as dewatering case and $CO_2$ 10% and $N_2$ 90% case resulted in the highest methane recovery among the mixed gas cases. On the other hand, the results of economic analysis showed that $CO_2$ 20% and $N_2$ 80% case made the highest total production profit. Therefore, both the recovery of methane and economical efficiency should be considered to apply ECBM process.

• Economic and Environmental Geology
• /
• v.57 no.2
• /
• pp.177-184
• /
• 2024

This study was conducted to find a way to reduce the production of cakes generated in the domestic aggregate production process. Cakes from 8 wet aggregate producers were collected and particle size was analyzed. Samples were collected step by step from an aggregate producer A, particle size analysis was performed, and the material balance was calculated before and after an sand recovery unit by modeling the production process. As a result of the particle size analysis of eight cakes, one sample contained 50% sand, and the rest contained about 5% to 25% sand. The results showing that the cake contained a variety of sand in cakes may indicate that the recovery efficiency of the sand recovery units in the field varied. Sieve analysis of the samples showed that the generation of sand particles increased 2.8 times during the third crushing compared to the second crushing, and more cake particles were generated. As a result of simulating the sand recovery unit model, the lower the cut point of the cyclone and dewatering screen, the higher the sand production and the less cake production appeared. In order to reduce the production of cake in the field, it was determined that an optimal operation of the sand recovery unit was necessary in the aggregate production process.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2000.11a
• /
• pp.407-416
• /
• 2000

국방 부문에 종사하는 관리자들은 국방정보시스템 사업관리에 있어서 최신정보기술에 대한 기본적인 사항은 알고있어야 효율적이고 효과적이며 성공적인 사업관리를 진행할 수 있을 것이다. 국방 부문에 종사하는 관리자들이 저비용 고효율의 국방정보시스템을 건설하고 운영 유지관리 하기 위하여 알아야 할 핵심 및 최신정보기술은 크게 인공지능기술, 멀티미디어 정보화 기술, 가상현실 기술, 시뮬레이션 기술, 텔레프레즌스 기술, 나노테크놀로지 기술, 데이터베이스 기술, 병렬처리 기술, 로봇공학 기술, 소프트웨어 공학에 관련된 기술 등이 있다. 그러나 국방부문에 종사하는 정보통신 전문 인력을 제외한 관리자들이 국방관련 사업관리를 수행하면서 정보기술에 대한 이해 수준이 비교적 낮기 때문에 효율적으로 국방사업을 준비, 계획, 추진하기 어려운 실정이다. 따라서 국방부문에 종사하는 관리자들이 정보기술을 알기 쉽게 이해할 수 있도록 국방부문 핵심지능형정보기술 발전 및 군 활용방안을 이해하기 쉽도록 작성하며 효율적인 사업관리가 이루어질 수 있는 방안을 연구하였다. 본 논문은 국방부문핵심 지능정보기술 식별 및 활용방안을 연구하여 핵심적으로 식별된 사항들을 우리 국방부문의 $C^4$I(지휘, 통제, 통신, 컴퓨터시스템)시스템, 내장형 무기시스템, 각종 교육훈련 정보시스템, 자원관리 정보시스템 등에 어떻게 적용할 것이며 적용시 기대효과는 무엇인가를 제시토록 하여 국방부문에 종사하는 관리자들이 각종 국방사업을 조정, 통제, 확인, 감독, 준비/계획하면서 참고하여 저비용 고효율의 국방관련 각층 사업을 관리할 수 있는 능력을 배양시키도록 연구를 수행하였다. 국방관련 각종 사업을 관리할 수 있는 능력을 배양시키도록 연구를 수행하였다. 국방부문 핵심지능정보기술 발전 및 활용 방안에 포함될 주요 내용을 요약하여 제시하였다.의 경향성을 나타내는 오차 주기(error cyc1e)를 이용함으로써 고객들의 수요의 경향성을 좀 더 세밀한 부분까지 파악할 수 있게 해 준다.ction, secondary electron microscopy, atomic force microscoy, $\alpha$-step, Raman scattering spectroscopu, Fourier transform infrared spectroscopy 및 micro hardness tester를 이용하여 기판 bias 전압이 DLC 박막의 특성에 미치는 영향을 조사하였다. 분석결과 본 연구에서 제작된 DLC 박막은 탄소와 수소만으로 구성되어 있으며, 비정질 상태임을 알 수 있었다. 기판 bias 전압의 증가에 따라 박막의 두께가 감소됨을 알 수 있었고, -150V에서는 박막이 거의 만들어지지 않았으며, -200V에서는 기판 표면이 식각되었다. 이것은 기판 bias 전압과 ECR 플라즈마에 의한 이온충돌 효과 때문으로 판단되며, 150V 이하에서는 증착되는 양보다 re-sputtering 되는 양이 더 많을 것으로 생각된다. 기판 bias 전압을 증가시킬수록 플라즈마에 의한 이온충돌 현상이 두드러져 탄소와 결합하고 있던 수소원자들이 떨어져 나가는 탈수소화 (dehydrogenation) 현상을 확인할 수 있었으며, 이것은 C-H 결합에너지가 C-C 결합이나 C=C 결합보다 약하여 수소 원자가 비교적 해리가 잘되므로 이러한 현상이 일어난다고 판단된다. 결합이 끊어진 탄소 원자들은 다른 탄소원자들과 결합하여 3차원적 cross-link를 형성시켜 나가면서 내부 압축응력을 증가시키는 것으로 알려져 있으며, hardness 시험 결과로 이것을 확인할 수 있었다. 그리고 표면거칠기는 기판 bias 전압을 증가시킬수록 더 smooth 해짐을 확인

• Journal of the Korean Electrochemical Society
• /
• v.11 no.3
• /
• pp.165-169
• /
• 2008

The effect of reduction of carbon dioxide by CODH(Carbon Monoxide Dehydrogenase) was compared on glassy carbon and gold working electrodes. In case of gold electrode, the choice of the optimum applied potential is very important since $H_2$ evolution can be mixed with $CO_2$ reduction. On the other hand, efficient $CO_2$ reduction was observed up to -650 mV vs. NHE on glassy carbon in neutral solution due to the larger overpotential for $H_2$ evolution on glassy carbon surface than that on gold surface. The optimum potential for $CO_2$ reduction was found to be $-570{\sim}600\;mV$ vs. NHE. The current efficiency of $CO_2$ to CO decreased dramatically at more negative potential according to the activity of enzyme decrease and the hydrogen evolution.

• Membrane Journal
• /
• v.23 no.4
• /
• pp.257-266
• /
• 2013

The main purpose of this study is to develop a commercial scale of pervaporative process equipped with hollow fiber membrane modules, being able to effectually purify organic solvent at high temperature well over its boiling point under high vapor pressure. Three constituent technologies have been developed; 1) to fabricate braid-reinforced hollow fiber membrane stable in high pressure and high temperature application, 2) to design and fabricate a commercial scale of hollow fiber membrane module, and 3) to design and fabricate a pilot scale of pervaporation equipment system. The developed hollow fiber membrane possesses a membrane performance superior to the membrane of Sulzer (Germany) which is the most-well known for pervaporation process, and the membrane module equips hollow fiber membranes of $4.6m^2$ and the pervaporation system can treat organic liquid at 200 L/h, which is based on the dehydration of 95 wt% isopropyl alcohol (IPA). Since the membrane module is designed to flow in and pass through the inside of individual hollow fiber membrane, not to involve both the formation of feed's dead volume observed in flat-sheet membrane module and the channeling of feed occurring inside hollow fiber bundle which lower membrane performance seriously, it showed excellent separation efficiency. In particular, the module is inexpensive and has less heat loss into its surrounding, in compared with flat-sheet membrane module. In addition, permeant can be removed effectively from the outer surface of hollow fiber membrane because the applied vacuum is conveyed uniformly through space between fibers into respective fiber, even into one in the middle of the hollow fiber bundle in which the space between fibers is uniform in distance. Since the hollow fiber membrane pervaporation system is the first one ever developed in the world, our own unique proprietary technology can be secured, preoccupying technical superiority in export competitive challenges.