• 접착 및 계면
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• 제19권2호
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• pp.84-94
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• 2018

Electrically debonding adhesives[EDA], one of the controlled delamination materials[CDM] is reviewed. CDM can be defined as the ability to separate adhesive bonded assemblies without causing damage to the substrates. Its application includes electronics, medical surgery, dentistry, building and general manufacturing where the opportunity to separate assemblies is important. There are several important mechanisms of EDAs; faradaic reaction, phase separation and anode detachment, cathodic debonding, gas emission mechanism, and mechanical stresses. These mechanisms are reviewed with various research results. Since the mechanism behind the electrochemical debonding of adhesives is not well understood, this review aims to help the research scientists in the industries. Finally, new applications of EDA are introduced as new business opportunity.

• 자원리싸이클링
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• 제26권4호
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• pp.3-8
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• 2017

산화-환원반응은 수용액에서 일어나는 여러 중요한 반응중 하나이다. 산화-환원반응의 평형을 해석하는 것은 습식제련에서 침출, 분리 및 전기화화반응과 같은 단위공정을 설계하는데 있어 큰 도움이 된다. Frost도를 작성하는 방법을 설명하고, Frost도와 Latimer 표로부터 불균등화반응과 균등화반응이 일어나는 조건을 해석하였다. 또한 Frost도로부터 얻을 수 있는 정보에 대해 고찰하였다.

• Bulletin of the Korean Chemical Society
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• 제18권8호
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• pp.880-886
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• 1997

Ab initio calculations were carried out on the gas phase acid-catalyzed hydrolysis reactions of sulfinamide using the 3-21G* basis sets. Single point calculations were also performed at the MP2/6-31G* level. The first step in the acid-catalyzed hydrolysis of N-methylmethanesulfinamide, Ⅰ, involves protonation. The most favorable form is the O-protonated one, Ⅱ, which is then transformed into a sulfurane intermediate, Ⅲ, by addition of a water molecule. The reaction proceeds further by an intramolecular proton transfer from O to N (TS2), which is followed by N-S bond cleavage (TS3) leading to the final products. The rate determining step is the N-S bond cleavage (TS3) at the RHF/3-21G* level, whereas it becomes indeterminable at the MP2/6-31G*//3-21G* level of theory. However, the substituent effect studies with N-protonated N-arylmethanesulfinamide, ⅩⅢ, at the MP2/6-31G*//3-21G* level support the N-S bond breaking step as rate limiting.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.80-85
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• 2016

Acoustic cavitation can induce various sonochemical effects including pyrolysis and radical reactions and sonophysical effects including microjets and shockwave. In environmental engineering field, ultrasound technology using sonochemical effects can be useful for the removal and mineralization of recalcitrant trace pollutants in aqueous phase as one of emerging advanced oxidation processes (AOPs). In this study, the effect of liquid height, the distance from the transducer to the water surface, on sonochemical oxidation reactions was investigated using KI dosimetry. As the liquid height/volume increased (40~400 mm), the cavitation yield steadily increased even though the power density drastically decreased. It was found that the enhancement at higher liquid height conditions was due to the formation of standing wave field, where cavitation events could stably occur and a large amount of oxidizing radicals such as OH radicals could be continuously provided.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권1호
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• pp.35-41
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• 2006

It is well known that concentration of C-reactive protein(CRP) in the serum increase as nonspecific reaction of the various tissue injury. The CRP, synthesized in the hepatocyte, is one of 'acute phase proteins' in the serum. The main signal patterns of this protein are regulated by synthesis of interleukin-I secreted from macrophage in the area of tissue injury. Many studies were performed for quantitative analysis for CRP according to various surgical operation, but the study for fracture patients associated with trauma, especially in mandible, are rare. The mandible fracture have intrinsic danger for infection in oral bacteria associated with open wound in oral cavity, and, are difficult for detection of tissue reaction between surgical swelling and infection by facial swelling. In this study, quantitative analysis for CRP associated tissue injury in mandibular fracture and surgical intervention was done, the results were as follows: 1. After initial mandibular trauma, the value of serum CRP diminished sequentially, most high value was presented in post-traumatic 2 days. 2. The CRP was diminished significantly 2 days after surgical intervention, and maintained normal value in 5 days after surgery. 3. The change of CRP are higher value in surgical intervention than initial trauma, it suggested that tissue injury from surgery was severe than trauma. 4. The high value of CRP was obtained in mandibular fracture combined soft tissue injury than no associated soft tissue injury. 5. In measurement of CRP according to surgical approach, highest serum value in patients of combined intra-oral and extra-oral approach was showed, and intra-oral approach, extra-oral approach, in sequential orders. 6. The CRP value are more higher in patient of 2 fracture site than only one fracture site. From the results obtained in this study, CRP has showed different values in mandibular fracture associated with severity of tissue injury and surgical intervention, and quantitative analysis of CRP value in serum can be applied to the clinical management of mandibular fracture.

• 한국세라믹학회지
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• 제45권11호
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• pp.734-738
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• 2008

Ettringite$(3CaO{\cdot}Al_2O_3{\cdot}3CaSO_4{\cdot}32H_2O)$, one of the hydrated phase of Portland cement is usually formed in the early stage of hydration by the reaction of tricalciumaluminate$(C_3A)$ and gypsum. The rapid and strong crystal growth of separated rod-shaped ettringite have been utilized for the preparation of special cements of rapid setting, high strength and non-shrinking properties. The ettringite also has been noticed as a promising materials for the immobilization of various waste ions because of its unique crystal structure which has abundant channels and exchangeable ionic compounds. In this study, the formation and growth behavior of the ettringite was investigated in the system $C_3A-CaSO_4-H_2O$ using $C_3A$ clinker and gypsum to obtain a microporous body for waste ion immobilization. Ettringite was revealed to form by the dissolution-precipitation mechanism and the bulk body was by the entangled growth of rod-shaped ettringite crystals. The hardened body was composed of nearly pure rod-shaped ettringite interlocked each other with adequate mechanical strength. The homogeneity of structure, pore size, specific surface area and porosity of the hardened body were influenced by reaction temperature, water/powder ratio and the curing time. The hardened body prepared with water/powder ratio of 1 at $24^{\circ}C$ for one day showed excellent morphological properties for the purposed materials.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2577-2582
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• 2013

A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM)2) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the $Ni(DBM)_2$ ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by $Ni(DBM)_2$ across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over $Br^-$, $NO_2{^-}$, $NO_3{^-}$, $CO{_3}^{2^-}$, $CH_3COO^-$ and $SO{_4}^{2^-}$ ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.

• 미생물학회지
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• 제34권3호
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• pp.137-143
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• 1998

수계에서 전분 가수분해 효소의 transglycosylation 반응을 이용하여 배당체(glycoside)를 합성하였다. Glycosyl donor인 가용성전분과 glycosyl acceptor인 benzylalcohol을 기질로 하여 ${\alpha}$-amylase에 의해 합성되는 배당체는 glucose의 1번 OH기에 benzylalcohol이 ${\alpha}$형태로 결합한 benzylalcohol-${\alpha}$-glucoside(BG)와 benzylalcohol-${\alpha}$-maltoside(BM)이었다. pH 5.0의 반응에서는 주로 BG가, pH 8.0의 반응에서는 BM만이 합성되는 특이한 반응양상을 보였다. Transglycosylation 반응의 최적조건은 가용성전분 50 mg/ml, benzylalcohol 50 mg/ml, 온도 $30-35^{\circ}C$, 효소량 10 unit/ml이었으며, 합성된 BG는 ${\alpha}$-glucodisase에 의해 glucose와 benzylalcohol로 가수분해되었으며 BM의 경우는 pH 5.0에서는 glucose와 BG로 가수분해되었으나 pH 8.0이상에서는 전혀 분해되지 않았다. BM과 구조적으로 유사한 maltotriose는 pH 5.0에서 glucose와 maltose로 가수분해 되었으나 transglycosylation반응은 거의 일어나지 않았으며 pH 8.0에서는 가수분해도 transglycosylation반응도 일어나지 않았다.

• 한국항공우주학회지
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• 제48권9호
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• pp.681-689
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• 2020

본 논문에서는 유도형 탄약의 모사 기체를 제작하고 공중에서 탄체에 롤축 회전을 인가한 뒤 롤축 저속 회전 중인 탄체의 롤각 추정 성능을 실험적으로 검증한 방법과 결과를 소개한다. 멀티로터형 무인기를 모선으로 사용해 유도형 탄약 모사 기체에 초기 속도와 고도를 부여하였으며 탄체 투하, 탄체 회전, 롤각 추정 및 안정화로 이어지는 비행 시험 시나리오를 통해 롤각 추정 결과를 분석한다. 약 200m의 고도에서 수평 방향으로 15m/s의 속력으로 탄체를 투하한 뒤 내부의 반동차(Reaction Wheel)를 사용하여 탄체를 회전시켰으며 특히, 상용 GPS/INS와의 비교를 통해 롤각 추정 결과를 제시한다. 아울러, 반동차를 이용하여 공중에서 탄체를 롤축 회전시키는 메커니즘들을 비교하고 실제 구현한 결과도 소개한다.

• Journal of Korean Society for Atmospheric Environment
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• 제23권E1호
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• pp.16-28
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• 2007

An improved method was developed to determine gas-phase hydrogen peroxide($H_2O_2$) and organic hydro-peroxides (ROOH) in real-time, The analytical system for $H_2O_2$ is based on formation of hydroxybenzoic acid (OHBA), a strong fluorescent compound. OHBA is formed by a sequence of reactions, photoreduction of Fe(III)-EDTA to Fe(II)-EDTA, the Fenton reaction of Fe(II)-EDTA with $H_2O_2$, and hydroxylation of benzoic acid. By use of this analytical method rather than a previous similar method, Fenton reaction time was reduced from 2 min. to 30s. Air samples were collected by a surfaceless inlet to prevent inlet line losses. With a special arrangement of the sampling apparatus, sample delivery time was drastically reduced from ${\sim}5\;min\;to\;{\sim}20\;s$. The automated system was found to be sensitive, capable of continuous monitoring, and affordable to operate. A comparison of this method with a well-established one showed an excellent linear correlation, validating applicability of this technique to $H_2O_2$ determination. The system was applied to field measurements conducted during summertime of 2004 in Gwangju, South Korea. $H_2O_2$ was found to be a predominant species of peroxides. The diurnal variation of $H_2O_2$ displayed the maximum in early afternoon and the broad minimum throughout night. $H_2O_2$ was correlated positively with ozone, photochemical age, and temperature, however, negatively with $NO_x$ and relative humidity.