• Journal of the KSME
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• v.29 no.6
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• pp.573-580
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• 1989

현재 한국의 자동차 공업은 80년대 초반부터 급격한 발전으로 세계의 다른 자동차 생산국으로부 터 경계의 대상이 되고 있다. 그러나 그 내면을 살펴보면 아직도 중요한 기술은 거의 대부분 일 본이나 독일, 미국 등 자동차 선진국의 기술에 의존하고 있으며 특히 엔진 분야는 대부분 외국 기술에 의존하고 있다고 해도 과언이 아니다. 엔진은 자동차 생산원가의 약 30%를 차지하며 자동차의 성능을 좌우하는 경우 기술료 지급은 물론이며 부품구매 선택의 여지가 없어진다. 또한 요즈음과 같이 상품의 수명주기가 짧게 되어 가는 추세 하에서는 시장의 요구에 대처해나가는 엔지니어링 적응력이 부족하게 되면 결국 경쟁성을 상실하게 된다. 그러나 이러한 문제점을 인 식하면서도 80년대 초까지 독자적인 엔진개발을 하지 못했던 원인은 크게 2가지로 분석할 수 있다. 첫째는 한국의 자동차 회사들의 기술 축적의 미약과 둘째는 독자개발의 낮은 투자효율성 이다. 즉 엔진과 변속기를 기술 도입할 때 기술료 지급은 자동차 생산댓수당 5-6만원에 달하지만 엔진과 변속기를 독자개발시의 투자비는 약 300-500억원에 달하므로 간단한 산술적 계산으로는 모델당 100만대를 생산하여야만 투자의 가치가 있는 것으로 보여진다. 물론 위에서 언급한 바와 같은 여러 가지 요인에 의하면 이 숫자보다 훨씬 적은 생산량으로도 경쟁성이 확보될 것으로 예상된다. 이제 한국의 자동차 생산량도 연간 백만 대를 상회하는 수준이며 앞으로도 급격한 양과 질적인 팽창이 기대되고 있는 시점에 자동차 메이커들은 각사 모두 독자적인 고유 엔진 개발을 착수하였으며 일부 회사는 이미 성공을 거두어 양산 준비를 하고 있는 것으로 알고 있다. 그러나 아직도 엔진의 설계부터 양산까지 걸리는 기간이 타 선진 메이커에 비하면 상당히 길며 이로 인해 신제품의 경쟁력 저하가 우려되고 있는 상태이다. 이러한 문제점 해결에 도움을 주기 위해서 학계는 기업체의 기술 개발방향과 전략을 이해하는 것이 필요하다.grightarrow$cn-semistratifiable over$\longrightarrow$semistratifiable over $\alpha$ 2, 어떤 공간이 cn-Semistratifiable over $\alpha$이기 위한 필요충분 조건은 그것이 linearly cushioned cn-pairnet를 갖는 것이다. 3. cn-semistratifiable over $\alpha$의 부분공간 역시 cn-semistratifiabie over $\alpha$ 하다. 4. on-semistratifiable over $\alpha$의 유한개의 적공간 역시 cn-semistratifiabie over $\alpha$한다. 5. 폐 cn-semistratifiable over $\alpha$ 부분공간들의 합공간 역시 on-semistrbtifiable over $\alpha$ 하다. 6. 폐연속 net-cevering 함수에 의하여 cn-semistratifiable over $\alpha$ 성질이 보존된다. 보잘것이 없었고, 현재에도 각 시도별 또는 대학주관의 경시대회가 있으나 거국적인 호응을 받지 못했다. 물론 국제 대회에 참석시키는 것은 엄두도 내지 않았다.로 나타났다. 4. 코코넛과 소나무수피의 경우 암모니아 가스에 대한 흡착 능력은 거의 비슷한 것으로 사료되며, 코코넛의 경우 전량을 수입에 의존하고 있다는 점에서 국내 조달이 용이하며, 구입 비용도 적게 소요되는 소나무수피를 사용하는 것이 경제적이라고 사료된다. 5. 마지막으로 악취제거 미생물균주를 접종한 소나무수피 50%와 펄라이트 30%의 혼합재료를 24시간 동안 장기간 운전 실험을 수행한 결과 암모니아 99.06%, 황화수소 96.61%의 제거

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.217-224
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• 2011

of materials and simplification of process. Micro-blasting is one of the promising method for recycling of waste wafer due to their simple and low cost process. Therefore, in this paper, we make recycling wafer through the micro-blaster. A surface etched by micro-blaster forms particles, cracks and pyramid structure. A pyramid structure formed by micro-blaster has a advantage of reflectivity decrease. However, lifetime of minority carrier is decreased by particles and cracks. In order to solve this problems, we carried out the DRE(Damage Romove Etching). There are two ways to DRE process ; wet etching, dry etching. After the DRE process, we measured reflectivity and lifetime of minority carrier. Through these results, we confirmed that a wafer recycled can be used in solar cell.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.203-203
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• 2019

도시화로 인한 불투수면의 증가는 물순환 왜곡, 비점오염원 발생 및 수생태계 건상성 훼손 등을 야기시키며, 이를 해결하기 위하여 다양한 LID 기법을 적용하고 있다. 일반적으로 LID 내 적용 되는 여재들은 무기성여재로 중량이 크고 미세공극의 부재로 물리화학적 및 생물학적 저감기능이 제한적이다. 따라서 본 연구에서는 중량성이 낮은 생물폐자원을 선정하여 LID 시설 적용성평가를 수행하고자 한다. 생물폐자원은 발생량, 경량성 및 용이성을 고려하여 꼬막껍질(CS)과 호두껍질(WS)을 선정하였다. 생물폐자원의 산화부식을 고려하여 무기성 여재인 화산석과 혼합하여 Bioretention 시설에 적용하였으며, 여재 혼합비율에 따라 총 3가지의 Case 로 구성하였다. 식생은 구절초와 꽃댕강나무를 식재하였으며, 여재의 물리적 특성 분석을 위하여 적용 전과 후의 SEM(Scanning Electronic Microscope)을 수행하였다. 모니터링은 도로퇴적물 100g과 물 110L를 제조하여 인공강우유출수를 이용하여 수행하였으며, $0.0003{\sim}0.007m^3/sec$의 유속으로 주입하였다. 시설의 유입 및 유출부에서 유량 측정 및 수질 시료를 채취하였으며, 채취된 시료는 수질오염공정 시험법에 준하여 입자상 물질, 유기물, 영양물질 및 중금속 등을 분석하였다. Bioretention 시설의 모니터링 결과를 이용하여 물수지 및 TSS 저감 효율을 산정하였으며. 물수지 분석결과 시설의 저류율은 Case 1(soil) > Case 3(WS+RV) > Case 2(CS+RV) 순으로 나타났다. 시설 내 공극률이 가장 낮았던 Case 1에서 저류율이 약 55%로 가장 높게 것으로 분석되었다. Case 3(WS+RV)은 Case 2(WS+RV)와 시설 내 공극률이 유사함에도 불구하고 저류율이 약 10% 높은 것으로 분석되었다. 오염물질 저감효율 분석 결과, TSS와 TP의 제거효율은 모든 Case에서 약 75% 이상으로 높게 나타났으며, COD의 경우 모래를 적용한 Case 1에 비해 생물폐자원인 꼬막껍질과 호두껍질을 적용한 Case에서 약 1.3배 이상 높게 나타났다. 호두껍질과 꼬막껍질의 SEM 분석 결과 표면에 다공성이 형성되어 있는 것으로 조사되었다. 이는 여과 및 저류기작으로 인한 물순환 효과증대와 다공성과 돌기사이로 인한 입자상의 물질 여과 및 흡착으로 인하여 오염물질의 제거효율이 증대 된 것으로 평가된다. LID시설 내 생물폐자원과 무기성여재를 적절히 배합하여 복합여재로 조성할 경우 침하현상을 방지할 뿐만 아니라 저류 및 침투기능 향상과 미생물의 서식환경을 제공하기에 물순환 회복 및 비점오염물질 저감에 기여할 것으로 평가된다.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1241-1248
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• 2021

In order to figure out various environmental problems, various governments and companies are investigating more environmentally policies and technologies. In other words, activated carbon is widely used for the adsorption of different harmful gases and waste liquid treatment. However since the required surface properties are different in various industry, depending on the adsorption properties, the development of activated carbon demand in different ways. In this work, we have investigated and developed the activated carbon surface to improve the hydrophilic properties by nitric acid treatment through reforming of activated carbon.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.2
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• pp.163-170
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• 2021

This study was conducted to create a technology to remove acne bacteria with human-friendly materials. First, the Cutibacterium acnes (C. acnes) were adsorbed to the mica disc to grow, and then the biofilm was checked through an atomic microscope to see if the biofilm had grown. Based on the topographic image, the shape changed round, the size was 17% longer on average, and the phase value of the resonance frequency separating materials was observed as a single value, the biofilm grown by covering the extracellular polymeric substrate (EPS). As a result of processing 50 mM of amino acids in the matured biofilm, the concentration of C. acnes decreased when valine, serine, arginine and leucine were treated. Scanning with nanoindentation and AFM contact modes confirmed that the hardness of biofilms treated with Valine (Val) increased. This indicates that an AFM tip measured cell which may have more solidity than that of EPS. The experiment of fluorescent tagged to EPS displays an existence of EPS at the condition of 10 mM Val, but an inhibition of growth of EPS at the 50 mM Val. Number of C. acnes was also reduced above 10 mM of Val. Weak adhesion of biofilm generated from an inhibition of EPS formation seems to induce decrease of C. acnes. Accordingly, we elucidated that Val has an efficiency which eliminates C. acnes by approach of an inhibition of EPS.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.61-72
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• 2004

The soil samples were collected from the paddy field near the mine tailing dumps in the abandoned Duckum mine in Korea. In the laboratory, the soil solution was extracted from the soil using centrifuge, and analysed for the chemical composition. Physical and chemical soil properties were also analysed. Kaolinite is the main clay minerals in the paddy soil and the CEC value is therefore relatively low. Nearly all soil samples show enrichment in their trace elemental concentrations(Cd, Cu, Pb and Zn) compared with natural background level. Some soil samples exceed the soil remediation intervention values for Cd, Pb and Zn and target value for Cu, when compared with Dutch standard, whereas As, Ni and Cr are in normal range. Lead concentrations in some samples near the mine tailing dumps also exceed the standard for remediation act for agricultural area set by Korean soil conservation law. The trace elemental concentrations are higher in the paddy soil nearer the mine tailing dumps and lower for the samples from distance. Similar trend with distance is found for the soil solution chemistry but the decrease with distance from the mine tailing dumps are sharper than the changes in soil chemistry. Cadmium, Cu and Pb concentrations in the soil solution are very low, ranging from a tenth and hundredths to a maximum of several mg/l, whereas their concentrations in soils are highly enriched for natural background. Most of the trace elements are thought to be either removed by reduced iron sulphides or iron oxides, depending on the redox changes. Geochemical equilibrium modelling indicate the presence of solubility controlling solid phases for Cd and Pb, whereas Zn and Cu might have been controlled by adsorption/desorption processes. Although pollutants migration through solution phase are thought to be limited by adsorption onto various Fe, Mn solid phases, the pollutants exist as easily releasable fractions such as exchangeable site. In this case, the paddy soil would act as pollutant pool, which will supply to plants in situ. whenever the geochemical conditions favour.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.420-430
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• 2005

This study was performed to change the hydrophilic $NH_4Y$-zeolite to the hydrophobic one for removal of VOCs by removing the $Al^{3+}$ in the zeolite-structure to increase the Si/Al ratio, for which the three pelleted $NH_4Y$-zeolite samples were contacted separately with the steam of $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$, respectively, in a stainless steel column for 4 hours. Then extraction of the ex-structure aluminum of the hydrolyzed zeolites with the nitric acids of 0.25, 0.50, 0.75, and 0.10 M at $90^{\circ}C$ in 500 mL-flasks, respectively, according to steam temperature were followed. XRD analysises of the dealuminated zeolites showed that the peaks of the zeolites that had been hydrolyzed with the steams of both $500^{\circ}C$ and $600^{\circ}C$ are distorted more with the increase of the concentration of nitric acid used for extraction of the ex-structure aluminums, however, those hydrolyzed with steam of $400^{\circ}C$ became amorphous phase when treated with the all nitric acids of four concentrations. Also the EDX analysises showed that the BET surface areas and TPVS of the zeolites that had been hydrolyzed with the steam of $600^{\circ}C$ were increased with the concentration of the nitric acid when the nitric acids of 0.25 M and 0.5 M had been used but decreased when the nitric acids of 0.75 M and 1.0 M had been used. These results led to the conclusion that both the $600^{\circ}C$ and $500^{\circ}C$-steam and the 0.5 M-nitric acid are appropriate to change the hydrophilic $NH_4Y$-zeolites to the hydrophobic one, which were proven by the measurement of the benzene and tolune-adsorbing capacities showing the same trend as the BET surface area and TPV The Si/Al ratios and water-adsorbing capacities of the dealuminated zeolites were increased and decreased, respectively, with the concentration of the nitric acids so that it showed that the hydrophobicity is increased.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.7
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• pp.432-440
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• 2015

Biochar, a by-product from pyrolysis of biomass, is a promising option to mitigate climate change by increasing soil carbon sequestration. This material is also considered to have potential to remediate a soil with heavy metal pollution by increasing the soil's adsorptive capacity. This study conducted the assessment of two biochars considering the climate change mitigation potential and heavy metal removal capacity at the same time. Two kinds of biochars (BC_Ch, TW_Ch) were prepared by pyrolyzing the biomass of burcucumber (BC_Bm) and tea waste (TW_Bm). The soils polluted with Pb were mixed with biochars or biomass and incubated for 60 d. During the incubation, $CO_2$, $CH_4$, and $N_2O$ were regularly measured and the soil before and after incubation was analyzed for chemical and biological parameters including the acetate extractable Pb. The results showed that only the BC_Ch treatment significantly reduced the amount of Pb after 60 d incubation. During the incubation, the $CO_2$ and $N_2O$ emissions from the BC_Ch and TW_Ch were decreased by 24% and 34% compared to the BC_Bm and TW_Bm, respectively. The $CH_4$ emissions were not significantly affected by biochar treatments. We calculated the GWP considering the production of amendment materials, application to the soils, removal of Pb, and soil carbon storage. The BC_Ch treatment had the most negative value because it had the higher Pb adsorption and soil carbon sequestration. Our results imply that if we apply biochar made from burcucumber, we could expect the pollution reduction and climate change mitigation at the same time.

• Journal of the Korean Wood Science and Technology
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• v.46 no.1
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• pp.17-28
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• 2018

In this study, catalytic activation using sulfuric acid lignin (SAL), the condensed solid by-product from saccharification process, with potassium hydroxide at $750^{\circ}C$ for 1 h in order to investigate its potential to nanoporous carbon In this study, catalytic activation using sulfuric acid lignin (SAL), the condensed solid by-product from saccharification process, with potassium hydroxide at $750^{\circ}C$ for 1 h in order to investigate its potential to nanoporous carbon material. Comparison study was also conducted by production of activated carbon from coconut shell (CCNS), Pinus, and Avicel, and each activated carbon was characterized by chemical composition, Raman spectroscopy, SEM analysis, and BET analysis. The amount of solid residue after thermogravimetric analysis of biomass samples at the final temperature of $750^{\circ}C$ was SAL > CCNS > Pinus > Avicel, which was the same as the order of activated carbon yields after catalytic activation. Specifically, SAL-derived activated carbon showed the highest value of carbon content (91.0%) and $I_d/I_g$ peak ratio (4.2), indicating that amorphous large aromatic structure layer was formed with high carbon fixation. In addition, the largest changes was observed in SAL with the maximum BET specific surface area and pore volume of $2341m^2/g$ and $1.270cm^3/g$, respectively. Furthermore, the adsorption test for three kinds of organic pollutants (phenol, 2,4-Dichlorophenoxyacetic acid, and carbofuran) were conducted, and an excellent adsorption capacity more than 90 mg/g for all activated carbon was determined using 100 ppm of the standard solution. Therefore, SAL, a condensed structure, can be used not only as a nanoporous carbon material with high specific surface area but also as a biosorbent applied to a carbon filter for remediation of organic pollutants in future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.291-298
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• 2001

Seawater, sediment and biota in the Kwangyang Bay were analyzed by gas chromatography/quartz furnace atomic absorption spectroscopy (GC-QFAAS) to investigate concentrations and distribution pattern of butyltin compounds (TBT, DBT, MBT) during February, April and July, 1996, Marine biota analyzed were Tapes japcnicus and Crassostrea gigas. The concentrations of tributyltin (TBT) in seawater were in the range of ND-15.7 ng/L for the surface and ND-68.5 ng/L for the bottom. The highest concentration of TBT in seawater was detected in April for the both, surface and bottom water. The maximum value of $TBT_{(bottom)}/TBT_{(surface)}$, 3.6 in April showed the increased input of TBT from the surface water in April compared to February (2.1) and July (0.9). The concentrations of TBT in the sediment were in the range of ND-8.5 ng/g dry wt. The highest concentration of TBT in the sediment was measured in July, This result seems to attributed to the removal of TBT from water column via sorption onto particulate matters to the relatively undisturbed underlying sediment and increased input of TBT by increased fluxes of detritus of marine plankton after spring bloom, in July. The mean values of partitioning coefficient ($K_d$) of TBT between seawater and sediment were $3.0\times10^3$(February), $7.4\times10^3$(April) and $9.4\times10^3$(July). The concentrations of TBT in biosamples were in the range of ND-93.30 ng/g dru wt. (T. japonicus) and ND-138.53 ng/g dry wt. (C. gigas). The seasonal variation of TBT contents in biota was remarkable. The $K_d$ (biological concentration factor) was $7-41\times10^3$ for T. japonicus. and $5-34\times10^3$ for C. gigas. The measured TBT concentrations in seawater in the study area was sufficient to cause the imposex of shellfish and to retard the growth of aquatic organisms including oyster upon chronic exposure.