• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.45.1-45.11
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• 2018

Objectives: This study was conducted to evaluate fluoride release and the micro-shear bond strength of resin-modified glass ionomer cement (RMGIC) in casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-remineralized caries-affected dentin (CAD). Materials and Methods: Exposed dentin surfaces of 30 human third molar teeth were divided into 2 equal groups for evaluating fluoride release and the micro-shear bond strength of RMGIC to CAD. Each group was subdivided into 3 equal subgroups: 1) control (sound dentin); 2) artificially demineralized dentin (CAD); 3) CPP-ACP remineralized dentin (remineralized CAD). To measure fluoride release, 15 disc-shaped specimens of RMGIC (4 mm in diameter and 2 mm in thickness) were bonded on one flat surface of the dentin discs of each group. Fluoride release was tested using ion chromatography at different intervals; 24 hours, 3, 5, 7 days. RMGIC micro-cylinders were built on the flat dentin surface of the 15 discs, which were prepared according to the assigned group. Micro-shear bond strength was measured after 24 hours water storage. Data were analyzed using 1- and 2-way analysis of variance and the post hoc least significant difference test (${\alpha}=0.05$). Results: Fluoride detected in solutions (at all intervals) and the micro-shear bond strength of RMGIC bonded to CPP-ACP-remineralized dentin were significantly higher than those bonded to artificial CAD (p < 0.05). Conclusions: Demineralized CAD consumes more fluoride released from RMGIC into the solution for remineralization than CPP-ACP mineralized dentin does. CPP-ACP increases the micro-shear bond strength of RMGIC to CAD.

• Journal of Pharmaceutical Investigation
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• 제40권spc호
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• pp.103-112
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• 2010

Pellets, which are multiple-unit dosage systems, have the several therapeutic advantages over single-unit dosage systems in oral drug delivery. This review focuses on the current status and explores extrusion-spheronization technique with special attention to controlled-release application of pellets including coated pellets for delayed release formulations, coated pellets for colon delivery, coated pellets for sustained drug delivery, sustained-release matrix pellets, pellets compressed into tablets, bioadhesive pellets, floating pellets, and pelletization with solubilization techniques.

• 오토저널
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• 제4권2호
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• pp.58-68
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• 1982

It is well known to diesel engineers that the heat release pattern is one of the most important factors affecting engine performance. Thorough research in heat release pattern has materially helped the progress in high-speed diesel engine development . This paper is based on the research conducted at KAIST and Daewoo Heavy Industry last year. The purpose of this paper is to determine the heat release pattern in combustion chamber of MAN M type, the famous low-noise engine. Thermodynamic cycle simulation was performed using Whitehous-Way's heat release pattern with modified coefficients and Annand's heat transfer model. Instantaneous temperature and pressure of gas in cylinder could be determined by the numerical solution of simultaneous equation of mass conservation, equation of energy conservation, and state equation of ideal gas. Calculated results were compared with measured values in some details emphasizing upon the factors affecting rate of heat release. The agreement was fairly good and revealed why M type should have lower burning velocity at the early part of combustion in spite of high injection rate. Additional results by parametric studies were given in relation to fuel injection conditions for further application to engine development.

• 폴리머
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• 제32권3호
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• pp.199-205
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• 2008

단백질 및 펩타이드의 서방형 약물전달체로서 소장점막하조직(SIS)으로 개질된 PLGA 담체를 제조하고자 하였으며, SIS/PLGA 담체는 용매 캐스팅/염 추출법에 의해 준비된 PLGA 담체에 SIS 용액을 첨가하여 단순 함침방법으로 제조하였다. 본 실험에서 사용된 돼지의 소장 점막층에서 유래된 SIS는 면역거부반응이 적어 생체재료로 널리 사용되고 있다. 제조된 PLGA 및 SIS/PLGA 담체를 SEM을 통한 표면 및 내부 관찰결과 두 담체 모두 열린 다공구조를 이루며, 특히 SIS/PLGA 담체는 PLGA 담체의 다공 내부에 SIS가 침투되어 작은 네트워크를 형성하고 있음을 확인하였다. 또한 단백질의 방출경향을 확인하기 위하여 형광이 결합된 소 혈청 알부민(FITC-BSA)을 PLGA 및 SIS/PLGA 담체에 담지시킨 후, 형광광도계를 통해 이들의 방출거동을 확인하였다. PLGA 담체와 비교할 때 SIS/PLGA 담체에서의 BSA의 방출은 초기방출량이 적고 지속적으로 일정량이 방출되는 거동을 확인할 수 있었으며 함량별 BSA 농도에 따른 SIS/PLGA 담체에서의 방출은 BSA의 양이 증가할수록 빠르고 많은 양이 방출되는 경향성 있는 방출패턴을 보임을 확인하였다. 결론적으로 PLGA 담체에 침투한 SIS 젤이 BSA의 급격한 초기방출을 억제하며, SIS로 개질된 PLGA 담체는 방출조절이 가능한 약물전달체로서 매우 유용할 것으로 사료된다.

• 전기화학회지
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• 제11권4호
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• pp.227-241
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• 2008

This article involves a unified treatment of equilibrium thermodynamics of the chemical reaction coupled with other interfacial (phase boundary) reactions. The modified (restrictive) chemical potential ${\mu}_k^+$, such as electrochemical potential, hydrostatic-chemical (mechanochemical) potential (exceptionally in the presence of the pressure difference) and surface-chemical potential, was first introduced under the isothermal and isobaric conditions. This article then enlightened the equilibrium conditions in case where the release of chemical energy is counterbalanced by the supply of electrical energy, by the supply of hydrostatic work (exceptionally in the presence of ${\Delta}p$), and finally by the release of surface energy, respectively, at constant temperature T and pressure p in terms of the modified chemical potential ${\mu}_k^+$. Finally, this paper focussed on the difference between chemical and electrochemical equilibria based upon the fundamentals of the isothermal and isobaric equilibrium conditions described above.

• Elastomers and Composites
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• 제56권2호
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• pp.72-78
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• 2021

A phase-change material (PCM) is a material that has the ability to delay heat transfer by absorbing heat from its environment or releasing heat to its environment while its phase changes from solid to liquid or liquid to solid at a specific temperature. As it is applied, it can contribute to environmental conservation such as energy savings and carbon dioxide emission reduction. In order for a PCM to store and release heat, the volume change during its phase transition should be large, and thus a phase transition space is required. When a PCM is used as a polymer additive, it is confined within the polymer, and there is no phase transition space; thus, its ability to absorb and release heat is significantly reduced. Therefore, in this study, porous silica was used to provide EVA/PCM compounds with sufficient space for their phase transition, and to improve the compatibility between the EVA and PCM, modified silica is used: surface-modified 5 wt% silica with 3-methacryloxypropyltrimethoxysilane. The compound was prepared and compared with the silica compound. The presence or absence of the modified silica surface modification was confirmed using Fourier-transform infrared spectroscopy and thermogravimetric analysis, the heat capacity of the compound was evaluated based on a differential scanning calorimetry analysis, and its mechanical strength and morphology were determined using scanning electron microscopy.

• 대한소아치과학회지
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• 제28권2호
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• pp.228-237
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• 2001

본 연구의 목적은 와동 충전시 충전재와 치질 사이에 개재되는 상아질 결합제가, 수복물에서 유리되는 불소가 와동 벽으로 침투하는 과정에 어떠한 영향을 주는지를 조사함이었고, 부가적으로 레진 강화형-글라스 아이오노머 시멘트의 접착에도 상아질 결합제를 도포 하는것이 치질과의 결합력을 강화시킬 수 있는지에 대해 평가하고자 하였다. Fuji II $LC^{(R)}$와 Dyract $AP^{(R)}$를 선정하여 상아질 결합제의 도포 여부에 따른 불소 유리량 측정과 전단 결합 강도를 비교분석하였으며, 치질 내로의 불소 침투 양상은 교환 시기에 있는 제2유구치에 Fuji II $LC^{(R)}$와 Dyract $AP^{(R)}$를 충전하고 3주내에 발거하여 EPMA로 분석하였다. 상아질 결합제는 불소 유리량을 현저하게 감소시키는 것으로 나타났으며(p<0.05) Fuji II $LC^{(R)}$의 경우 상아질 결합제의 도포가 결합강도를 증가시키지 못하였다. EPMA 분석결과 상아질 결합제는 충전재로부터 유리되어 나오는 불소가 치질 내로 확산되는 것을 방해하는 것으로 확인되었다.

• 대한족부족관절학회지
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• 제27권4호
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• pp.123-130
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• 2023

Purpose: "Hallux valgus" is a common disease encountered in clinical practice and is accompanied by foot deformities. Conservative treatment is commonly used in the early stages of hallux valgus. On the other hand, surgical treatment often becomes necessary as the deformity progresses. Surgical treatments involve various osteotomy methods or joint fusion procedures combined with soft tissue release, and outcomes from these surgical treatments are generally favorable. This study compared two soft tissue release techniques in the hallux region. Materials and Methods: This study conducted a retrospective cohort study on 48 participants who underwent surgical treatment for hallux valgus at a single institution from March 1, 2018, to March 31, 2023. A scarf osteotomy was performed in all cases, and the "Modified Mcbride procedure" or "Trans-articular approach" was done for soft tissue release. Hallux valgus angle (HVA), intermetatarsal angle (IMA), and the degree of subluxation of the lateral sesamoid were measured through simple foot radiographs taken before surgery and one year after surgery. Results: In the Modified Mcbride procedure group, HVA, IMA, and the sesamoid position grade decreased from 34.94° to 9.98°, 15.64° to 5.44°, and 2.47 to 0.44, respectively. In the trans-articular approach group, HVA, IMA, and the sesamoid position grade decreased from 33.42° to 7.34°, 15.06° to 6.03°, and 2.17 to 0.58, respectively. There was no significant difference in these changes between the preoperative and one-year postoperative measurements for both techniques (p-value>0.05). Conclusion: A radiological assessment of soft tissue release through the Modified Mcbride procedure and trans-articular approach in hallux valgus did not show significant differences. Therefore, both surgical techniques can be considered in the distal soft tissue release for a hallux valgus correction.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.368-376
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• 2004

영광부지의 추적자 확산실험결과의 자료동화를 통하여 Gaussian plume 모형의 확산인자의 수정과 추적자 방출률 평가를 수행하였다. 부지 주변의 여러 지점에서 관측한 실험결과에 선형계획법을 적용하여 확산평가에 있어선 가장 불확실성이 크다고 알려진 확산인자를 수정하였다. 원자력 비상시 초기 대응평가에 사용되는 정보 가운데 가장 큰 불확실성을 포함한 선원항 정보를 추적자 농도 분포로부터 추정하였다. 실험 당시의 추적자 방출량을 모른다고 가정하고 Gaussina plume 모형의 예측치와 확산실험의 실측치를 이용한 최소자승법을 적용하여 방출률을 추정하였다. 확산인자를 수정한 후 Gaussian plume 모형의 예측력은 방출점으로 3km 및 8km 떨어진 포집선 두 경우 모두 증가하는 것으로 나타났다. 실험당시의 방출률을 모른다고 가정하고 관측지점의 농도에 최소자승법을 적용한 결과 24%이내에서 실제 방출률을 양호하게 추정하고 있음을 확인할 수 있었다.

• Journal of Korean Neurosurgical Society
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• 제65권2호
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• pp.307-314
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• 2022

Objective : The percutaneous thread transection technique is a surgical dissecting method using a dissecting thread inserted through a needle under ultrasound guidance without skin incision. As the new dissecting threads were developed domestically, this cadaver study was conducted to compare the effectiveness and safety between the new threads (ultra V sswire and smartwire-01) and a pre-existing commercial dissecting thread (loop & shear) by demonstrating a modified looped thread cubital tunnel release. Methods : The percutaneous cubital tunnel release procedure was performed on 29 fresh cadaveric upper extremities. The pre-existing commercial thread was used in 5 upper extremities. The two newly developed threads were used in 24 upper extremities. Two practitioners performed the procedures separately. After the modified looped thread cubital release, anatomical and histological analyses were performed by a blinded anatomist. The presence of the dissected cubital tunnel and damaged adjacent soft tissue was assessed. Results : Out of the 29 cadaveric upper extremities, 27 specimens showed complete dissection of the Osborne ligament and the proximal fascia of the flexor carpi ulnaris muscle. One specimen was incompletely dissected in each of the ultra V sswire and smartwire-01 groups. There were no injuries of adjacent structures including the ulnar nerve, ulnar artery, medial antebrachial cutaneous nerve, or flexor tendon with either the commercial thread or the newly developed threads. The anatomical analysis revealed clear and sharp incisional margins of the cubital tunnel in the Smartwire-01 and loop & shear groups. All three kinds of threads maintained proper linear elasticity for easy handling during the procedure. The smartwire-01 provided higher visibility in ultrasound than the other threads. Conclusion : The newly developed threads were effective and safe for use in the thread cubital tunnel release procedure.