치암중초약의 돌연변이유발 및 돌연변이유발 억제효과

이현철 대한미생물학회 1987 大韓微生物學會誌 Vol.22 No.2

Ten species of herbae, which have been used to treat cancers in Chinese medicine, were tested to investigate their mutagenieity or antimutagenicity in S. typhimurium TA97, TA98, TA100, TA1S35, and TA1538. Scolopendra centipede was weakly active in reversion of the frameshift mutation in S. typhimurium TA97 strain and the base-pair substitution in TA100 and TA1535 strains. Other herbae such as Coix lachryma, Dianthus superbus, Tricanthoshse kirilowii, Eupatorium formo- sanum, Lithospermum erythrorliizon, Arisaema japonicum, Curcuma aedoaria, Helicteres angustifolia, and Euonymus sieboldianus did not show any of the mutagenic potential, regardless of the metabolic activation with rat hepatic microsomal fraction. Dianthus superbus, Eupatorium formosanum, and Euonymus sieboMianus exhibited suppressive activities on microbial mutagenesis of N-methyl-N-nitrosoguanidine, a basepair substitution mutagen, in TA1535 and TA10G tester strains. The antimutagenic activities of Dianthus superbus and Euonymus sie- boldianus appeared to be dose-dependant.

Collective Excitation and Spectral Function of Quantum Wires in the Presence of Rashba Spin-Orbit interactions and a Parallel Magnetic Field

이현철,양승열 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.3

The eects of the electron-electron interaction on the spin-¯lter proposed by St·reda and ·Seba are studied. Using bosonization methods, we obtain the velocity of the collective mode and the spectral function exactly at low energy. These results can be experimentally veri¯ed by tunneling experiments.

Post-Renal Transplant Diabetes Mellitus in Korean Subjects: Superimposition of Transplant-Related Immunosuppressant Factors on Genetic and Type 2 Diabetic Risk Factors

이현철 대한당뇨병학회 2012 Diabetes and Metabolism Journal Vol.36 No.3

Postrenal transplantation diabetes mellitus (PTDM), or new-onset diabetes after organ transplantation, is an important chronic transplant-associated complication. Similar to type 2 diabetes, decreased insulin secretion and increased insulin resistance are important to the pathophysiologic mechanism behind the development of PTDM. However, β-cell dysfunction rather than insulin resistance seems to be a greater contributing factor in the development of PTDM. Increased age, family history of diabetes, ethnicity, genetic variation, obesity, and hepatitis C are partially accountable for an increased underlying risk of PTDM in renal allograft recipients. In addition, the use of and kinds of immunosuppressive agents are key transplant-associated risk factors. Recently,a number of genetic variants or polymorphisms susceptible to immunosuppressants have been reported to be associated with calcineurin inhibition-induced β-cell dysfunction. The identification of high risk factors of PTDM would help prevent PTDM and improve long-term patient outcomes by allowing for personalized immunosuppressant regimens and by managing cardiovascular risk factors.

활성황토를 혼입한 모르터의 물리적특성에 관한 연구

이현철,고성석 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.3

The hwangtoh is one of the traditional and environment friendly construction materials used as part of a wall, plastering material, and ondol (Korean underfloor heating system) with stones and woods in Korean style house. It has many advantages such as; high storage of heat, auto-purification, antibiotic ability, and emission of far infrared rays. But, it is not developed and used in modern construction material now, because of its low strength and properties of dry shrinkage crack. According to the recent researches and studies, it is evaluated for natural pozzolanic material like flyash or pozzolan. Its possibility in construction material is high because its chemical and mineralogical proportions are like Metakaolin and Kaolinite. In this point of view, this study aims to analyze the basic physical properties of hwangtoh mortar through an experiment with various activation conditions of hwangtoh and mixing conditions of mortar, for the purpose of increasing the possibility of using it as modern construction material.

유세포분석법에 의한 혈소판항체 검사에서 냉동 혈소판의 유용성

이현철,원동일 대한수혈학회 2010 大韓輸血學會誌 Vol.21 No.2

Background: Among immunofluorescence assays using flow cytometry for platelet antibodies, a direct method (platelet-associated IgG tesing, PAIgG) and an indirect method (antiplatelet antibody testing, APA) are used with fresh platelets. In this study, we investigated whether frozen platelets can be serve as an alternative to fresh platelets for these assays. Methods: Platelet rich plasma was separated and stored at −80oC. Prior to use, frozen platelets were thawed at room temperature for 30 min and then tested in the same manner as fresh platelets. Thirty eight samples for PAIgG and 93 samples for APA were included in this study to compare qualitative determinations and sample/control ratios of meanfluorescence intensity (MFI) for anti-IgG-PE staining between fresh and frozen platelets. Results: In comparison of qualitative determinations between 2 kinds of platelets, PAIgG was concordant in 27 positive and 9 negative cases, with a total 38 cases (94.7%, κ=0.865, P<0.001). In 2 remaining cases,fresh platelet was suitable for their diagnosis. APA was concordant in 46 positive and 33 negative cases for a total 93 cases (84.9%, κ=0.693, P<0.001). In 5 of 8 discordant cases, frozen platelets were suitable for their diagnosis. In comparison of MFI ratios, frozen platelets was significantly correlated with fresh platelets in both tests (PAIgG: fresh vs. frozen=6.5±11.0 vs. 4.0±5.5 (r=0.924, P<0.001); APA: 3.9±5.3 vs. 2.4±2.6(r=0.656, P<0.001)), but the values for frozen platelets decreased more than those of fresh platelets. Conclusion: For APA, although both fresh and frozen platelets have their own advantages, sole use of frozen platelet was more helpful for making a diagnosis than the sole use of fresh platelets. For PAIgG, frozen platelets can be suggested as alternatives to fresh platelets in inevitable cases or for convenience of both patients and assay procedures, it requires accepting a slight decrease in positivity rate (from 29/38 to 27/38). (Korean J Blood Transfus 2010;21:132-139) 배경: 유세포분석법으로 혈소판항체를 검출하기 위한 면역형광법으로서, 직접법인 혈소판결합항체 검사(platelet-associated IgG testing, PAIgG)와간접법인 항혈소판항체 검사(antiplatelet antibody testing, APA)를 통상적으로 신선 혈소판을 이용하여 시행한다. 본 연구에서는 이들 검사에서 신선 혈소판 대신 냉동 혈소판을 이용하는 것이 가능한지 조사하였다. 방법: 냉동 혈소판으로서 혈소판풍부혈장을 분리하여 −80oC에 보관하다가 실온에서 30분간 녹인 후 신선 혈소판과 동일하게 취급하였다. PAIgG 38 검체, APA 93 검체를 대상으로, PAIgG와 APA 에서 두 종류의 혈소판의 anti-IgG-PE 염색의 정성 판정과 평균형광강도(mean fluorescence intensity,MFI)의 시험/대조 비(MFI ratio)를 비교하였다. 결과: 정성 판정에서, PAIgG는 총 38예 중 양성27예, 음성 9예에서 일치(94.7%, κ=0.865, P<0.001)하였고 불일치한 2예에서 신선 혈소판의 결과가진단에 합당하였다. APA는 총 93예 중 양성 46예, 음성 33예에서 일치(84.9%, κ=0.693, P<0.001)하였고 불일치한 8예 중 5예에서 냉동혈소판의결과가 진단에 합당하였다. MFI ratio 비교에서,두 검사 모두 신선과 냉동 혈소판간 상관관계가유의하였으나(PAIgG: fresh vs. frozen=6.5±11.0vs. 4.0±5.5 (r=0.924, P<0.001); APA: 3.9±5.3 vs. 2.4±2.6 (r=0.656, P<0.001)), 냉동 혈소판의 값이신선 혈소판보다 감소하였다. 결론: APA의 경우, 두 혈소판 모두 고유의 장점이 있었으나, 냉동 혈소판만 사용하는 것이 신선 혈소판만 사용하는 것보다 더 진단에 도움이되었다. PAIgG의 경우, 양성률이 약간 감소(29/38에서 27/38)하는 것을 감수한다면, 부득이한 경우나 환자와 검사 편의를 위해 신선 대신 냉동 혈소판을 사용할 수 있을 것으로 생각된다.

전력제어의 연속 TPC 비율을 사용한 목표물 속도추정

이현철 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.11

CDMA 를 사용하는 무인기 편대비행에서, Inner Loop Power Control 에 사용하는 재래식 SIR 계산 방식대신에 link-budget 을 기초로한 SIR 계산방식을 속도추정에 적용하는 방법을 소개한다. 제안한 SIR 계산방식을 3 개의 Inner Loop Power Control 알고리듬에 적용하고 연속 TPC 비율을 계산하여 이것이 목표물의 속도와 선형관계임을 보인다. CS-CLPC 와 FSPC 알고리듬 사용시 연속 TPC 비율을 측정하면 목표물의 속도를 추정할 수 있음을 알 수 있다. The power control with Code Division Multiple Access (CDMA) systems for communications in the formation flight of Unmanned Aerial Vehicles (UAVs) is applied to speed estimation with a link-budget based Signal-to-Interference Ratio (SIR). The proposed SIR is applied to three inner loop power control algorithms and the fact that the consecutive TPC ratio has linear relationship with target speed is shown. It is concluded that target speed estimation can be realized by measurement of consecutive TPC ratio when CTR Step-size Closed Loop Power Control (CS-CLPC) and Fixed Stepsize Closed Loop Power Control (FSPC) algorithms are used.

건설산업 경영관리전략 효율화를 위한 평가지표에 관한 연구

이현철,고성석 大韓建築學會 2010 大韓建築學會論文集 : 構造系 Vol. No.

<P>The Korean domestic capability evaluation of the construction industry entails a public announcement of results of a comprehensive evaluation of construction accomplishments, company financial position, and technological capability. The system excludes environmental evaluation criteria in making a judgment on the degree of overall management effectiveness. Rather, the capability of construction companies is based on accumulated technology and accomplishments, thereby limiting utilization of the system as an evaluative index for management effectiveness. Thus, a new standard systematic evaluation is required to assess management effectiveness. Accordingly, the purpose of this study was to add internal and external management factors to the evaluation criteria used within the construction capability system, to choose parameters useful to identify effective management, and to provide a new index of management evaluation. The management effectiveness evaluation factors suggested in this study are given relative weights using a hierarchical pair-wise comparison, and principal evaluation criteria are selected. Also, based on this analysis, a table of scores is composed to provide an evaluation standard for management effectiveness. The authors hope to alter the current management evaluation process within the construction industry, de-emphasizing the role of accomplishments, and rather rewarding logical and intelligent management, thus promoting responsible company activities.</P>

WT평면에서의 디지탈 청각 보조 신호 처리 시스템의 설계

이현철,석광원 대한의용생체공학회 1996 의공학회지 Vol.17 No.3

This paper presents digital hearing aids signal processing system in WT(wavelet transform) domain. For implementation of hearing aids in WT domain, the gain in frequency domain is approximated in WT domain. We also present the gain selection algorithm to deal with the change of input signal power. Most transform methods produce blocking effect, and this effect degrades the convergence rate of feedback canceller. As a solution, we proposed wavelet transform bascd feedback canceller. To evaluate the performance, we compared it with LOT (lapped orthogonal transform) method in the frequency domain. This system has not shown the blocking effect, and improves convergence rate as compared with the LOT based feedback canceller.

교량 케이블시스템의 모드변수에 관한 연구

이현철,조영훈,김진수,박경호 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 논문집 Vol.23 No.5

In recent years, the type of bridge where cables such as suspension bridge and cable-stayed bridge are the main factors in the construction of long-range bridges has been soaring. The effects of cables on these structures are very large, and for structural analysis, it is necessary to study the cable and the structural changes according to the mode characteristics of the cables. In particular, cables are directly connected to camber adjustment, which conveys load effects on girders to tower, and are important components in the overall structure, and since the initial tension on the construction is compared with the tension over time, this study was conducted to help identify the condition of the bridge's aging and abnormalities. Therefore, in this study, the characteristics of the mode from the mode analysis through the impact hammer to the mass of the cable and the change in the length of the cable are analyzed. 최근 들어 장대교량의 건설에 현수교, 사장교 등과 같은 케이블이 주 요소인 교량 형식이 급증하고 있다. 이와 같은 구조물에서 케이블이 미치는 영향은 매우 크며, 구조해석을 위해서 케이블에 대한 연구 및 케이블의 모드 특성에 따른 구조계의 변화를 연구해 볼 필요가 있다. 특히, 케이블은 거더에 가해지는 하중효과를 주탑으로 전달하는 캠버조절과 직결되고 전체 구조에서 중요한 부재로서, 가설시 가해지는 초기장력과 시간이 경과후 장력을 비교하므로서 교량의 노후상태와 이상유무를 파악하는 데 기여하고자 본 연구를 수행하였다. 따라서 본 연구에서는 충격해머를 통한 모드 해석으로부터 케이블의 질량과 케이블의 길이변화에 따른 모드의 특성을 파악할 수 있었고, 공용중에 있는 케이블에서는 위상각의 변화가 비례관계임을 확인하였다. 또한 저차모드에서 지배모드가 결정되는 특성을 MAC분석을 통하여 알 수 있었다.

춘계학술대회 : 포스타 연제 ; 전신성 홍반성 낭창 환자에서 발생한 다발성 피부섬유종 1예

이현철,윤철현,황계영 대한피부과학회 1993 대한피부과학회 학술발표대회집 Vol.45 No.1