• 정보보호학회논문지
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• 제19권2호
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• pp.63-74
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• 2009

2005년 Wang이 MD 계열 전용 해쉬함수에 대한 분석 결과를 발표함에 따라, MD 계열 전용 해쉬함수를 이용한 메시지 인증 프로토콜에 대한 분석 결과 또한 다수 발표되었다. CRYPTO'07에서 Fouque, Leurent, Nguyen은 Wang의 충돌쌍 공격을 이용한 MD4, MD5 기반 HMAC/NMAC의 내부 키 복구 공격과 외부 키 복구 공격을 소개하였다[4]. EUROCRYPT'08에서 Wang, Ohta, Kunihiro는 근사 충돌쌍(near-collision)을 이용한 MD4 기반 HMAE/NMAC의 외부 키 복구 공격을 소개하였다[2]. 즉, Wang 등은 새로운 근사 충돌쌍 특성을 이용하여 기 제안된 Fouque의 분석 방법을 향상시킴으로서 오라클 질의량을 $2^{88}$에서 $2^{72}$으로 감소시켰으며, MD4계산량 또한 $2^{95}$에서 $2^{77}$으로 감소시켰다. 본 논문에서는 분할-정복(divide and conquer) 공격을 이용한 새로운 MD4 기반 HMAC/NMAC의 외부 키 복구 공격 알고리즘을 제시한다. 본 논문에서 제시하는 분할-정복 공격을 이용한 공격알고리즘은 $2^{77.1246}$의 오라클 질의량과 $2^{37}$의 MD4 계산량으로 HMAC/NMAC의 외부 키를 복구할 수 있는 향상된 공격 방법이다.

• BMB Reports
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• 제50권2호
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• pp.55-57
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• 2017

Toll-like receptor 4 (TLR4) together with MD2, one of the key pattern recognition receptors for a pathogen-associated molecular pattern, activates innate immunity by recognizing lipopolysaccharide (LPS) of Gram-negative bacteria. Although LBP and CD14 catalyze LPS transfer to the TLR4/MD2 complex, the detail mechanisms underlying this dynamic LPS transfer remain elusive. Using negative-stain electron microscopy, we visualized the dynamic intermediate complexes during LPS transfer-LBP/LPS micelles and ternary CD14/LBP/LPS micelle complexes. We also reconstituted the entire cascade of LPS transfer to TLR4/MD2 in a total internal reflection fluorescence (TIRF) microscope for a single molecule fluorescence analysis. These analyses reveal longitudinal LBP binding to the surface of LPS micelles and multi-round binding/unbinding of CD14 to single LBP/LPS micelles via key charged residues on LBP and CD14. Finally, we reveal that a single LPS molecule bound to CD14 is transferred to TLR4/MD2 in a TLR4-dependent manner. These discoveries, which clarify the molecular mechanism of dynamic LPS transfer to TLR4/MD2 via LBP and CD14, provide novel insights into the initiation of innate immune responses.

• 한국생활과학회지
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• 제24권3호
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• pp.437-449
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• 2015

The purpose of this study was to investigate the quality characteristics of Dangmyon(starch vermicelli) prepared with mulberry leaves powder. Mulberry leaves powder was added in ratios (w/w) of 0% (CON), 0.5% (MD1), 1.0% (MD2), 1.5% (MD3). and 2.0%(MD4), and then proximate compositions, physicochemical properties, RVA, SEM, texture and sensory evaluations of the Dangmyon were measured. MD1~MD4 samples showed higher contents of moisture, crude lipid, crude protein and crude ash as well as pH compared to control (p<0.001). In terms of color, lightness (L), yellowness (b), and redness (a) decreased as the mulberry leaves powder increased. The results of RVA properties analysis on all samples showed that control had the highest. With regard to the texture of Dangmyon samples, the scores of hardness, adhesiceness, gumminess, chewiness, resilience of CON was significantly higher than the samples MD1~MD4 (p<0.001), but the scores of springiness, cohesiveness was not significantly among samples. The result of observation on the cross section of Dangmyon added with mulberry leaves powder showed that number, size of cavity more increase compared to the control. In sensory evaluation, the scores of appearance, flavor, taste and overall preference for MD3 were significantly higher than the samples (CON, MD1, MD2, and MD4). From the findings, this study suggests that 1.5% addition of mulberry leaves powder was effective for preparation of Dangmyon in the aspects of the consumer acceptability.

• 품질경영학회지
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• 제50권4호
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• pp.735-749
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• 2022

Purpose: The purpose of this study is to investigate whether the Management Discussion and Analysis (MD&A) has an impact on auditors' audit efforts. MD&A is a means of disclosure that provides information about a company from the management's perspective in financial reporting. The MD&A is a standardized format of nonfinancial information that can be useful for the stake-holders. The auditors have incentives to utilize the nonfinancial information contained in the MD&A for their decision-making. We posit that the MD&A disclosure quality is associated with the level of audit efforts. Methods: We hand-collect the disclosure data from the Financial Supervisory Service of Korea (the Korean SEC). Results: By employing two measures of audit efforts, we document evidence that the quality of MD&A is associated with both audit hours and audit fees. Conclusion: It implies that the auditors perform intensive audit work for companies with high-quality disclosure of MD&A. The study contributes to the literature by providing the first approach to examine the association between the MD&A disclosure and audit efforts.

• 한국IT서비스학회지
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• 제22권4호
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• pp.21-35
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• 2023

Software as Medical Devices (SaMD) is a growing category of medical devices that are composed of software to perform one or more medical purposes. SaMD is less likely to cause physical harm compared to conventional medical devices, particularly medical electrical equipments, and may be more vulnerable to privacy issues. This difference was acknowledged and resulted in introducing new regulation guidance specifically for cybersecurity of SaMD. It guides stakeholders of SaMD what to consider in what context in terms of cybersecurity. This study examines the current guidance of how cybersecurity is considered for SaMD by analyzing current medical device standards, then suggest which concept or details beyond current medical device standards may be applicable through analysis of international standards documents published for software in general.

• Molecules and Cells
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• 제24권1호
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• pp.119-124
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• 2007

TLR4 together with CD14 and MD-2 forms a pattern recognition receptor that plays an initiating role in the innate immune response to Gram-negative bacteria. Here, we employed the surface plasmon resonance technique to investigate the kinetics of binding of LPS to recombinant CD14, MD-2 and TLR4 proteins produced in insect cells. The dissociation constants ($K_D$) of LPS for immobilized CD14 and MD-2 were $8.7{\mu}m$, and $2.3{\mu}m$, respectively. The association rate constant ($K_{on}$) of LPS for MD-2 was $5.61{\times}10^3M^{-1}S^{-1}$, and the dissociation rate constant ($K_{off}$) was $1.28{\times}10^2S^{-1}$, revealing slow association and fast dissociation with an affinity constant $K_D$ of $2.33{\times}10^6M$ at $25^{\circ}C$. These affinities are consistent with the current view that CD14 conveys LPS to the TLR4/MD-2 complex.

• Journal of Dairy Science and Biotechnology
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• 제32권2호
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• pp.147-156
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• 2014

본 연구는 원유로부터 비만 억제 능력이 있는 젖산균을 분리 및 동정하고, 이 균주의 생리적 특성을 규명하여 상업적으로의 이용가능성을 검토하고자 실시하였다. 이를 위해 Modified MRS 분별배지를 사용하여 노란색 집락을 형성하는 균주를 대상으로 각각 Anti-lipase activity와 Anti-adipogenic activity가 우수한 균주를 선발한 결과, MD366 균주가 최종 선발되었다. MD366 균주는 lipase 억제활성 $65.03{\pm}0.94%$, 지방분화억제활성 $27.4{\pm}1.4%$로나타났으며, 동정결과Enterococcus faecalis로 판명되었고, Enterococcus faecalis MD366으로 명명하였다. E. faecalis MD366의 최적 생장 온도는 $37^{\circ}C$ 이었으며, 담즙산과 산성의 pH에서 모두 우수한 생존력을 나타내었다. 효소활성은 전반적으로 낮았으나 acid phosphatase에 대해 비교적 높은 효소 활성을 나타내었다. 항생제 내성 실험 결과 neomycin, kanamycin, vancomycin에 내성이 있는 반면, novobiocin에 감수성을 나타냈으며, Escherichia coli, Salmonella Typhimurium과 Staphyloccous aureus에 대해 각각 80.4%, 60.2%와 65.4%의 억제 효과를 지니고 있는 것으로 나타났다.

• Advances in pediatric surgery
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• 제1권1호
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• pp.33-39
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• 1995

The incidence of Meckel's diverticulum(MD) in general population has been assessed as 2 percent. The major complications of MD are bleeding, perforation, and intestinal obstruction. In spite that the complication rate of Meckel's diverticulum is relatively high(about 4.2% during a lifetime), the preoperative diagnostic rate of complicated MD is very low. Authors investigated the clinical characteristics of complicated MD to improve the diagnostic rate. 16 patients with complicated Meckel's diverticulum who were operated upon at the Department of Pediatric Surgery, Seoul National University Children's Hospital from June 1985 to December 1993 were reviewed. Among the 16 patients with complicated MD, 12 patients(75%) were under 2 year-old and male were predominant(88%). The most common complication was bleeding patients with bleeding MD (8 cases) were diagnosed preoperatively as MD. 8 patients with other complications(perforation : 4 cases, obstruction : 4 cases) could not be suspected as complicated MD except one patient who had previous history of melena. These patients were diagnosed after exploratory laparotomy under the various impression other than MD. Among 12 patients with ulcer related complications such as bleeding and perforation, heterotopic gastric mucosa was found in 11 patients. In conclusion, in any children with unexplained acute abdomen, especially under 2 years old, complicated MD must be included in differential diagnosis. In children with obscure lower gastrointestinal bleeding, $^{99m}Tc$-pertechnetate scintigraphy is a useful diagnostic tool to rule out bleeding MD.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 1995년도 종합학술발표회논문집
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• pp.126-137
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• 1995

VDM-SL(Vienna Development Method - Specification Language)은 다양한 표준들의 정확한 기술을 위해 제시되고 있는 형식규격어의 하나로서 특히 보안표준의 표현에 적합한 형식규격어이다. 이러한 VDM-SL을 사용하여 보안표준의 표현 및 실행코드 생성의 정확성과 편리성을 제공하기 위한 다양한 도구들이 개발되고 있으며 이들 중 IFAD VDM-SL Toolbox는 가장 많은 기능을 구진 도구이다. 본 논문에서는 IFAD WDM-SL Toolbox를 이용해 해쉬알고리즘의 하나인 MD4 Message Digest Algorithm을 형식적 표현기법으로 나타내고 이를 바탕으로 참조구현 코드를 C++로 생성하는 방법을 설명한다. 또한 형식적 표현기법과 IFAD VDM-SL Toolbox를 이용해 생성된 참조구현코드의 실행 결과를 MD4의 테스트 벡터 (test vector)를 이용하여 RSA사에서 구현한 MD4 알고리즘과 비교 분석하여 형식적 표현기법을 이용하여 생성된 코드의 활용성에 대해 설명하고자 한다.

• 한국미생물·생명공학회지
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• 제20권4호
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• pp.377-383
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• 1992

Bacillus thuringiensis 7균주를 한국의 토양에서 분리하여 특성을 연구했다. 상기의 7균주를 HL-8, 10, 12, 13, 14, 15와 16으로 명명했으며, 이들 균주들은 세포내의 다양한 형태의 parasproal endotoxin crystal과 내생포자를 형성한 것을 위상차현미경으로 관찰했다. 분리균주들의 생화학적인 특성은 이미 알려진 균주들과 유사했으나, 특이한 차이점을 가지고 있었다. 각 분리균이 가지고 있는 플라스미드를 분리하여 분자량과 수를 조사한 결, HL-8 과 HL-10은 6종류의 플라스미드를 가지고 있었으며, 분자량의 범위는 3.01-15.1Md 이었고, HL-12균주는 4종규의 플라스미드를 가지고 있었으며, 분잘량의 범위는 5.4-21.9Md이었고, HL-13균주도 4종류의 플라스미드를 가지고 있었으나 분자량은 차이가 없었다. HL-15균주도 3종류의 플라스미드를 가지고 있었으며, 분자량의 범위는 2.4~13.5Md이었고, HL-15균주도 3종류의 플라스미드를 가지고 있었으며, 분자량의 범위는 3.4~11.4Md이었고, HL-16도 3종류의 플라스미드를 가지고 있었으며, 분자량의 범위는 2.4~20.1Md이었다. 상기 분리균는 공히 ampicillin, bacitracin, cephalothin, methicillin과 penicillin G에 저항성을 나타냈다. HL-8과 15는 48시간내에 Culex pipiens 모기 3령유충에 100%의 살충성을 나타냈고, 다른 균주는 이보다 낮았다. 특히 HL-13은 살충성이 없었다.