콩고산 코발트 정광으로부터 제조한 매트의 고온고압침출

김건하,강가희,김수경,손정수,권경중,Kim, Gunha,Kang, Ga-hee,Kim, Sookyung,Sohn, Jeongsoo,Kwon, Kyungjung 한국자원리싸이클링학회 2015 資源 리싸이클링 Vol.24 No.4

이차전지 재료 등으로 사용되는 코발트는 콩고 민주공화국 등 일부 국가에 편중되어 있다. 국내 코발트의 안정적인 공급을 위한 해외 코발트광과 코발트 제련 기술의 확보는 필수적이다. 이에 본 실험에서는 콩고산 코발트 정광(Co ~ 8 wt%, Cu ~ 19 wt%, Fe ~ 3 wt%)을 용융환원시켜 얻어지는 합금상에 매트 내 황의 비율을 달리해 만든 2가지 조성의 매트를 제조했으며, 주된 원소는 19 ~ 21wt% Co, 39 ~ 41wt% Cu, 7 ~ 9wt% Fe이다. 매트 분쇄산물을 autoclave를 이용한 고온고압침출법으로 3가지의 영향(산화제 유무, 침출제인 황산 농도, 매트 제조 시 투입되는 황 함량)을 고려해 실험을 진행했다. 먼저 산화제(산소)의 존재는 Co 침출률 향상을 위해 필수적이며 낮은 농도의 황산을 사용하더라도 Co를 전량 침출시킬 수 있다. 둘째 산소 분위기에서 높은 황산농도는 Cu와 Fe의 침출률을 증가시켜 선택적인 Co 침출을 방해한다. 마지막으로 매트 내 황 함량은 Co의 침출률에는 영향이 크지 않음을 알 수 있었다. Cobalt is abundant only in some countries including Democratic Republic of the Congo. It would be necessary to secure overseas Co ores and Co extraction technology. Two kinds of matte varying the sulfur content were manufactured by smelting reduction of Co concentrate containing ~8 wt% Co, ~19 wt% Cu, and ~3 wt% Fe. The amount of Co, Cu and Fe was concentrated to 19~21 wt%, 39~41 wt%, and 7~9 wt% respectively in the resulting matte. High-pressure leaching of matte was performed in an autoclave with considering the effect of oxidizing agent, $H_2SO_4$ concentration as a lixiviant, and the amount of sulfur added to the matte. An oxidizing agent (oxygen) is necessary to improve Co leaching efficiency enabling usage of a dilute $H_2SO_4$ leaching agent. An increase in $H_2SO_4$ concentration prevents selective leaching of Co, and the sulfur content in matte has a minor influence on the Co leaching efficiency.

Effect of Individual and District-level Socioeconomic Disparities on Cognitive Decline in Community-dwelling Elderly in Seoul

김건하,이혜아,박혜숙,이동영,조인호,최성혜,최경규,정지향 대한의학회 2017 Journal of Korean medical science Vol.32 No.9

This study was to investigate the effects of individual and district-level socioeconomic status (SES) on the development of cognitive impairment among the elderly. A 3-year retrospective observational analysis (2010–2013) was conducted which included 136,217 community-dwelling healthy elderly who participated in the Seoul Dementia Management Project. Cognitive impairment was defined as 1.5 standard deviations below the norms on the Mini-mental status examination. In the individual lower SES group, the cumulative incidence rate (CIR) of cognitive impairment was 8.7% (95% confidence interval [CI], 8.64–8.70), whereas the CIR in the individual higher SES group was 4.1% (95% CI, 4.08–4.10). The CIR for lower district-level SES was 4.7% (95% CI, 4.52–4.86), while that in the higher district-level SES was 4.3% (95% CI, 4.06–4.44). There were no additive or synergistic effects between individual and district-level SES. From this study, the individual SES contributed 1.9 times greater to the development of cognitive impairment than the district-level SES, which suggests that individual SES disparities could be considered as one of the important factors in public health related to cognitive impairment in the elderly.

가축 매몰지 사후관리 방법

김건하 한국환경농학회 2011 한국환경농학회 학술대회집 Vol.2011 No.1

Role of Sand Capping in Phosphorus Release from Sediment

김건하,정우혁 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.6

Sand is the simplest capping material proposed to date to contain phosphorus in sediment in situ. This research was carried out to understand the role of sand capping in the speciation and release of phosphorus from sediment. Clean sand was laid on sediment sampled at a eutrophicated lake in one dimensional columns with different capping thicknesses. It could be understood from the experiments that sand capping with a thickness of less than 50 mm reduced the phosphorus concentration by over 85% and was effective in reducing the amount of phosphorus released from the sediment. Thicker sand capping reduces the amount of phosphorus released from the sediment to a greater extent. Since sand capping retards the release of phosphorus from the sediment, a higher fraction of non-apatite P (NA-P) was able to be converted into the less soluble Apatite-P (AP).

가축매몰지 소멸시 잔존물 처리방안

김건하 대한상하수도학회 2018 상하수도학회지 Vol.32 No.3

Burials for the rapid disposal of carcasses have diverse and profound effects on the rural living condition, natural environment, and local economy throughout construction, management and final destruction of burials. In this study, possible residue excavated from standard burials, storage using FRP (Fiberglass Reinforced Plastic) tanks, and microbial-treated burials are characterized as carcasses, contaminated soil by leachate, and wasted plastic film. Treatment technologies for volume reduction of the residue including composting, rendering, and thermal hydrolysis were investigated. If the solid and liquid residues generated during volume reduction treatment are directly transferred to the environmental facilities, it may cause disorder due to high concentrations of organics, antibiotics, and lipid. Benefits and drawbacks of composting as a volume reduction techniques are extensively investigated. We also discussed that proper treatment of excavated soils and the reusing the treated soil as agricultural purpose. For the protection of public health and worker’s hygiene, treatment criteria including produced residue qualities, and quality standards for the treated soil as agricultural use are required. In addition, Scientific manual for the proper treatment of residues is required. It is necessary to consider the establishment of a pretreatment facility to the occurrence of large-scale residue treatment.

Neuroprotective Effect of Lacosamide on Hypoxic-Ischemic Brain Injury in Neonatal Rats

김건하,변정혜,은백린 대한신경과학회 2017 Journal of Clinical Neurology Vol.13 No.2

Background and Purpose Lacosamide (LCM) is an antiepileptic drug that enhances the slow inactivation of sodium channels and modulates collapsin response mediator protein-2. LCM was recently demonstrated to exert a neuroprotective effect in a murine model of trau¬matic brain injury and status epilepticus. Assuming the same underlying excitotoxicity-related brain injury mechanism, we hypothesized that LCM would have a neuroprotective effect in hypoxic-ischemic brain injury. Methods We divided rats into three groups at each testing session: pre- or postfed with LCM, fed with normal saline, and sham. A hypoxic-ischemic brain injury was induced by subjecting 7-day-old rats to right carotid artery coagulation followed by 2.5 h of exposure to 8% oxygen. The animals were killed on postnatal day 12 to evaluate the severity of brain damage. Open field testing was also performed between week 2 and week 6, and the Morris water maze test was performed in week 7 after hypoxia-ischemia. Results The incidence of liquefactive cerebral infarction was lower in rats prefed with LCM at 100 mg/kg/dose, with the mortality rate being higher at higher doses (200 and 300 mg/kg/dose). The infarct areas were smaller in LCM-prefed rats in several brain regions including the hemisphere, hippocampus, cortex, and striatum. Spatial learning and memory function were better in LCM-prefed rats (p<0.05). No effect was observed in postfed rats. Conclusions This study suggests that LCM pretreatment exerts a neuroprotective effect on hypoxia-ischemia in neonatal rats. The obtained results suggest that LCM pretreatment could be used as an effective neuroprotective method for neonates under hypoxic-ischemic condi¬tions including heart surgery.

물환경분야 남북한 협력방안

김건하 대한상하수도학회 2020 상하수도학회지 Vol.34 No.1

With growing expectations for economic cooperation between the two Koreas, there is much interest in participating in the construction of infrastructure in North Korea. In particular, water and wastewater infrastructure is the four major social infrastructures in addition to housing, transportation, electricity and telecommunications. North Korea is known to have severe water pollution and ecosystem destruction in major rivers, water pollution and soil pollution in mining areas are serious, and water and sewage infrastructures in cities other than Pyongyang are known to be weak. Preemptive investment in water supply and drainage in North Korea is the foundation for securing the quality of life of the North Korean people and is the foundation of public health and industry. It is a leading investment to reduce the cost of unification and is a new growth engine for the construction industry. In this study, we proposed a plan to exchange and cooperate in water environment for building water infrastructure of North Korea by examining the data related to water quality, water resources, water disaster, related legal system and manpower exchange situation in North Korea.

Attention Deficit Hyperactivity Disorder in Epileptic Children

김건하,김지연,변정혜,은백린,이영준,서원희,은소희 대한의학회 2012 Journal of Korean medical science Vol.27 No.10

It is well-known that the prevalence of attention deficit hyperactivity disorder (ADHD) is higher in epileptic children than in the general pediatric population. The aim of this study was to compare the accompaniment of ADHD in epileptic children with well-controlled seizures and no significant intellectual disability with that in healthy controls. We included epileptic children between the ages of 6 and 12 yr visiting our clinic for six consecutive months and controls without significant medical or psychiatric illnesses. We excluded patients with intellectual disability or persistent seizures during the recent three months. The diagnosis of ADHD was based on the criteria of the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV). After exclusion of 84 patients, we enrolled 102 (54.8%)children (mean age, 9.4 ± 2.0 yr). Seven (7 of 102, 6.9%) were diagnosed with ADHD. As compared to control group (4 of 110, 3.6%), there was no difference in ADHD accompaniment (P = 0.29). No difference was observed in ADHD accompaniment according to seizure type and epilepsy syndrome. In conclusion, the accompaniment of ADHD in epileptic children with well-controlled seizures and no intellectual disability may not differ from that of the general pediatric population.

Mycoplasma pneumoniae associated stroke in a 3-year-old girl

김건하,서원희,제보경,은소희 대한소아청소년과학회 2013 Clinical and Experimental Pediatrics (CEP) Vol.56 No.9

Infectious diseases precede a significant proportion of acute ischemic strokes in children. Here, we report a case of acute ischemic stroke in a 3-year-old girl with a Mycoplasma pneumonia -associated respiratory tract infection. She developed an acquired prothrombotic state of protein S deficiency and had increased fibrinogen and fibrinogen degradation product levels and increased titer of antinuclear antibodies. However, these conditions were completely alleviated at the 1-month followup examination. Infection with M. pneumoniae may cause a transient prothrombotic state that can potentially cause a thrombus.

언어의 이해영역과 따라말하기영역의 Manual Tracing을 이용한 뇌영상 비교연구

김건하,정지향 대한치매학회 2007 Dementia and Neurocognitive Disorders Vol.6 No.2

Background: The brain area involved in language processing has long been fascinated the Neurologists. Even though anatomical imaging studies or autopsies have been used to define the area involved in each specific domain of language, the precise connections involved in comprehension to repetition are still unclear. To understand language network, we designed to manually trace the area of focal infarction in first-ever stroke patients manifesting aphasia to compare a specific comprehension defect type with a conduction defect type. Material and method The participants included 8 acute first-ever stroke patients with aphasia from April, 2005 to June, 2006. Five patients had a comprehension defect type (sensory) and three had a conduction defect type of aphasia. We assessed the patients’ symptomatic brain lesions with brain MRI and MR angiography and examined the language function using the K-WAB test, within 3 to 12 days of the stroke onset. Then we tried to correlate the specific type of aphasia with neuroanatomical locations by adding together manual drawings of the infarcted lesions drawn on translucent paper. Results There was little difference in anatomical lesion between comprehension defect type and conduction defect type of aphasia. However, almost all comprehension defect type of aphasia had larger size of infarct lesions involving superior temporal gyrus compared to the conduction defect type, which had more involvement in inferior parietal lobule. Discussion It is difficult to differentiate between comprehension and conduction types of aphasia just by anatomical location. However, the small sample size seemed to put a limitation on a meaningful outcome. Thus, further study including more study subjects and employing functional imaging such as SPECT and MRI volumetry needs to be done.