• 분석과학
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• 제6권1호
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• pp.93-106
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• 1993

8종의 염소화유기인제 농약에 대한 전자충돌식으로 이온화시킨 질량분석법에 대하여 연구하였다. 대부분의 경우, 염소 원소를 포함하는 특성이온들은 그들의 동위원소에 기인하는 $^{37}Cl$ 피크에 의해 쉽게 확인되어진다. 즉 깨어진 이온의 염소 동위원소($^{37}Cl$)에 기인하는 피크량의 비를 측정함으로써 염소 원자수를 알 수 있다. 또한, 유기인제 부분은 과거에 보고되었던 질량분석 메카니즘과 비교하였을 때, 대체로 잘 일치함이 관측되었다.

• 정보처리학회논문지B
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• 제11B권5호
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• pp.611-618
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• 2004

본 논문에서는 인터넷상의 대용량 자료에서 원하는 정보를 검색하기 위한 지원 기능으로서 분산 객체지향 데이타베이스에서 클래스를 분할하여 여러 사이트에 분산시키는 기법에 관하여 설계 및 구현하였다 제안된 분산 기법은 클래스의 분할 과정과 할당 과정으로 구성된다. 클래스의 분할 과정에서는 메소드, 계승 및 복합 객체와 같은 객체지항 데이터베이스의 특성을 반영하여 클래스를 분할하였으며 할당 과정에서는 저장, 질의 처리 및 전송비용을 고려하여 할당수식을 정의하였으며 이를 유전자 알고리즘을 이용하여 구현하였다.

• Geomechanics and Engineering
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• 제9권3호
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• pp.329-344
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• 2015

Cratering tests in rock are generally carried out to identify its fragmentation characteristics. The test results can be used to estimate the minimum amount of explosives required for the target volume of rock fragmentation. However, it is not easy to perform this type of test due to its high cost and difficulty in securing the test site with the same ground conditions as the site where blasting is to be performed. Consequently, this study investigates the characteristics of rock fragmentation by using the hydrocode in the platform of AUTODYN. The effectiveness of the numerical models adopted are validated against several cratering test results available in the literature, and the effects of rock mass classification and ground formation on crater size are examined. The numerical analysis shows that the dimension of a crater is increased with a decrease in rock quality, and the formation of a crater is highly dependent on a rock of lowest quality in the case of mixed ground. It is expected that the results of the present study can also be applied to the estimation of the level and extent of the damage induced by blasting in concrete structures.

• 터널과지하공간
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• 제20권5호
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• pp.325-331
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• 2010

이 연구에서는 사암 벤치에 대하여 V형과 경사 V형의 두 가지 기폭 패턴으로 대규모 발파를 실시하였다. 장약량은 비슷하였다. 발파 후 디지털 이미지 프로세싱 방법으로 파쇄석의 파쇄도를 평가하였다. 10 $m^3$ 용량 로우프 쇼벨의 싸이클 시간도 계측하였다. 그 결과는 경사 V형으로 기폭한 경우 파쇄성능이나 굴착기 성과가 더 향상된다는 것을 보여준다. 이 논문에서는 경사 V형 패턴이 V 형 패턴보다 더 나은 성능을 보이는 이유에 대하여 논한다.

• 한국정밀공학회지
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• 제29권9호
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• pp.1020-1025
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• 2012

In this study, we fabricated the superhydrophobic and super-water-repellent surface with the micro/nano scale structures using simple conventional silicon wet-etching technique and the black silicon method by deep reactive ion etching. These fabrication methods are simple but very effective. Also we reported the droplet impact experimental results on the micro/nano-scaled surface. There are two representative impact behaviors as "rebound" and "fragmentation". We found the transition Weber number between "rebound" and "fragmentation" statements, experimentally. Additionally, we concerned about the dimensionless spreading diameters for our super-water-repellent surface. The novel characterization method was introduced for analysis including the "fragmentation" region. As a result, our super-water-repellent surface with the micro/nano-scaled structures shows the different impact behaviors compared with a reference smooth surface, by some meaningful experiments.

• Clinical and Experimental Reproductive Medicine
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• 제45권3호
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• pp.101-109
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• 2018

In an age when a small quantity of sperm can lead to pregnancy through in vitro fertilization or intracytoplasmic sperm injection, selecting healthy sperm is important. Sperm DNA fragmentation (SDF) is known to be higher in infertile men. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) and the alkaline comet test are SDF tests that directly measure DNA damage and have shown closer correlations with assisted reproduction results than indirect tools such as the sperm chromatin structure assay or the sperm chromatic dispersion test. It is difficult; however, to endorse a single test as the best test overall; instead, it is best to select a testing method based on each patient's clinical condition and goals. In a couple struggling with infertility, if the male partner has a high level of SDF, he should aim to decrease SDF through lifestyle modifications, antioxidant treatment, and ensuring an appropriate duration of abstinence, and physicians need to treat the underlying diseases of such patients. If sperm DNA damage continues despite the patient's and physician's efforts, other methods, such as micromanipulation-based sperm selection or testicular sperm extraction, should be used to select healthy sperm with nuclear DNA integrity.

• Mass Spectrometry Letters
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• 제12권2호
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• pp.41-46
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• 2021

Collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD) are the widely used fragmentation technique in mass spectrometry-based proteomics studies. Understanding the fragmentation pattern from the tandem mass spectra using statistical methods helps to implement efficient spectrum analysis algorithms. The study characterizes the frequency of occurrence of multi-charged fragment ions and their neutral loss events of doubly and triply charged peptides in the CID and HCD spectrum. The dependency of the length of the fragment ion on the occurrence of multi-charged fragment ion is characterized here. Study shows that the singly charged fragment ions are generally dominated in the doubly charged peptide spectrum. However, as the length of the product ion increases, the frequency of occurrence of charge 2 fragment ions increases. The y- ions have more tendencies to generate charge 2 fragment ions than b- ions, both in CID and HCD spectrum. The frequency of occurrence of charge 2 fragment ion peaks is prominent upon the dissociation of the triply charged peptides. For triply charged peptides, product ion of higher length occurred in multiple charge states in CID spectrum. The neutral loss peaks mostly exist in charge 2 states in the triply charged peptide spectrum. The b-ions peaks are observed in much less frequency than y-ions in HCD spectrum as the length of the fragment increases. Isotopic peaks are occurred in charge 2 state both in doubly and triply charged peptide's HCD spectrum.

• Clinical and Experimental Reproductive Medicine
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• 제49권3호
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• pp.196-201
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• 2022

Objective: This prospective consecutive study investigated the variation in sperm DNA fragmentation (SDF) in multiple semen samples from patients with cancer. Methods: Eighty-one patients with various cancers underwent multiple semen collections on 3 consecutive days for sperm cryopreservation prior to cancer treatment. A commercial Halosperm kit was used to measure SDF. Within- and between-subject coefficients of variation were estimated via random-effects analysis of variance to assess the consistency of semen parameters and SDF. Intraclass correlation coefficients (ICCs) were calculated to assess the magnitude of the between-subject component of variance relative to the total variance. Results: The volume of semen in the day-2 and day-3 samples was significantly lower compared with the day-1 sample. Most parameters showed high ICC values, suggesting that within-subject fluctuations were small relative to the between-subject variability. The highest ICC values were identified for the SDF (ICC, 0.68; 95% confidence interval [CI], 0.45-0.84) and semen volume (ICC, 0.67; 95% CI, 0.45-0.84). Conclusion: Our findings showed that repeated ejaculates from patients with cancer had stable SDF levels.

• 분석과학
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• 제34권4호
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• pp.172-179
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• 2021

Oleanane-type triterpenoids exist as secondary metabolites in various plants. In particular, soyasaponin, an oleanane-type triterpenoid, is abundant in the hypocotyl of soybean, one of the most widely cultivated crops in the world. Depending on their chemical structure, soyasaponins are categorized as group A saponins or group DDMP (2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one) saponins. The different soyasaponin chemical structures present different health functionalities and taste characteristics. However, conventional phenotype screening of soybean requires a substantial amount of time for functionality of soyasaponins. Therefore, we attempted to use liquid chromatography with a photodiode array detector and tandem mass spectrometry (LC-PDA/MS/MS) for accurately predicting the phenotype and chemical structure of soyasaponins in the hypocotyl of five common soybean natural mutants. In this method, the aglycones (soyasapogenol A [SS-A] and soyasapogenol B [SS-B]) were detected after acid hydrolysis. These results indicated that the base peak and fragmentation differ depending on the chemical structure of soyasaponin with aglycone. Thus, a fragmentation database can help predict the chemical structure of soyasaponins in soyfoods and plants.

• Structural Engineering and Mechanics
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• 제82권6호
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• pp.713-724
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• 2022

Effects of coal tensile strength and plow configuration on the coal fragmentation process was modeled by two-dimensional particles flow code (PFC2D). Three tensile strength values, 0.5, 1,5 and 3.5 MPa were considered in this numerical study. The cutters of plow penetrated in the coal for 4 mm at a rate of 0.016 m/s. According to the PFC manual, the local damping factor was 0.7. Three failure mechanism of coal during the fragmentation process by plow were modelled. The coal material beneath the cutters showed the elastic, plastic and fracturing behaviors in this analysis. In all the models, the plastic zone was fractured and some micro-cracks were induced but the elastic zone remained undamaged. It was observed that the tensile strength affected the failure mechanism of coal significantly and as it increased the extent of the fractured zone underneath the plow cutter decreased during the fragmentation process.