• KIPS Transactions on Software and Data Engineering
• /
• v.8 no.11
• /
• pp.427-432
• /
• 2019

In this paper, we propose three approaches to modeling Android malware. The first method involves human security experts for meticulously selecting feature sets. With the second approach, we choose 300 features with the highest importance among the top 99% features in terms of occurrence rate. The third approach is to combine multiple models and identify malware through weighted voting. In addition, we applied a novel method of eliminating permission information which used to be regarded as a critical factor for distinguishing malware. With our carefully generated feature sets and the weighted voting by the ensemble algorithm, we were able to reach the highest malware detection accuracy of 97.8%. We also verified that discarding the permission information lead to the improvement in terms of false positive and false negative rates.

• Analytical Science and Technology
• /
• v.34 no.2
• /
• pp.68-77
• /
• 2021

Cannabis is one of the most abused drugs in Korea. The main psychoactive component in cannabis, Δ9-tetrahydrocannabinol, is metabolized to 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) and THCCOOH-glucuronide (THCCOOH-glu) in the human liver, whereby the amount of THCCOOH-glu found in urine is twice as high as that of THCCOOH. The analytical process adapted by the majority of urine drug-testing programs involves a two-step method consisting of an initial immunoassay-based screening test followed by a confirmatory test if the screening test result is positive. In this study, a qualitative gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the detection of THCCOOH in human urine, where THCCOOH-glu was converted into THCCOOH by alkaline hydrolysis. For purification of the urine extract prior to instrumental analysis, high-speed centrifugation was used to minimize interference. In addition, an injection-port derivatization method using ethyl acetate and N,O-bis(trimethylsilyl)-trifluoroacetamide containing 1 % trimethylchlorosilane was employed to reduce the time required for derivatization, and an aliquot of the final solution was injected into the GC-MS. The method was validated by measuring the selectivity, limit of detection (LOD), and repeatability. The sensitivity, specificity, precision, accuracy, Kappa, F-measure, false positive, and false negative rate were determined by comparing the GC-MS results with those obtained using the immunoassay. The LOD was determined to be 0.32 ng/mL, while the repeatability was within 9.1 % for THCCOOH. Furthermore, a comparison study was carried out, whereby the screening immunoassay exhibited a sensitivity of 86.4 % and a specificity of 100 % compared to GC-MS. The applicability of the developed method was examined by analyzing spiked urine and forensic urine samples obtained from suspected cannabis abusers (n = 221).

• Journal of Gastric Cancer
• /
• v.22 no.4
• /
• pp.395-407
• /
• 2022

Purpose: This study aimed to investigate the relationship between clinical and laboratory parameters and complication status to predict which patients can be safely discharged from the hospital on the third postoperative day (POD). Materials and Methods: Data from a prospectively maintained database of 2,110 consecutive patients with gastric adenocarcinoma who underwent curative surgery were reviewed. The third POD vital signs, laboratory data, and details of the course after surgery were collected. Patients with grade II or higher complications after the third POD were considered unsuitable for early discharge. The performance metrics were calculated for all algorithm parameters. The proposed algorithm was tested using a validation dataset of consecutive patients from the same center. Results: Of 1,438 patients in the study cohort, 142 (9.9%) were considered unsuitable for early discharge. C-reactive protein level, body temperature, pulse rate, and neutrophil count had good performance metrics and were determined to be independent prognostic factors. An algorithm consisting of these 4 parameters had a negative predictive value (NPV) of 95.9% (95% confidence interval [CI], 94.2-97.3), sensitivity of 80.3% (95% CI, 72.8-86.5), and specificity of 51.1% (95% CI, 48.3-53.8). Only 28 (1.9%) patients in the study cohort were classified as false negatives. In the validation dataset, the NPV was 93.7%, sensitivity was 66%, and 3.3% (17/512) of patients were classified as false negatives. Conclusions: Simple clinical and laboratory parameters obtained on the third POD can be used when making decisions regarding the safe early discharge of patients who underwent gastrectomy.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.7 s.349
• /
• pp.72-83
• /
• 2006

It is not a practical solution that the DDoS attacks or worm propagations are protected and responded within a domain itself because it clogs access of legitimate users to share communication lines beyond the boundary a domain. Especially, the DDoS attacks with spoofed source address or with bogus packets that the destination addresses are changed randomly but has the valid source address does not allow us to identify access of legitimate users. We propose a scheme of distributed network security management to protect access of legitimate users from the DDoS attacks exploiting randomly spoofed source IP addresses and sending the bogus packets. We assume that Internet is divided into multiple domains and there exists one or more domain security manager in each domain, which is responsible for identifying hosts within the domain. The domain security manager forwards information regarding identified suspicious attack flows to neighboring managers and then verifies the attack upon receiving return messages from the neighboring managers. Through the experiment on a test-bed, the proposed scheme was verified to be able to maintain high detection accuracy and to enhance the. normal packet survival rate.

• The Korean Journal of Pain
• /
• v.28 no.2
• /
• pp.105-108
• /
• 2015

Background: The most definitive diagnosis of neck pain caused by facet joints can be obtained through cervical medial branch blocks (CMBBs). However, intravascular injections need to be carefully monitored, as they can increase the risk of false-negative blocks when diagnosing cervical facet joint syndrome. In addition, intravascular injections can cause neurologic deficits such as spinal infarction or cerebral infarction. Digital subtraction angiography (DSA) is a radiological technique that can be used to clearly visualize the blood vessels from surrounding bones or dense soft tissues. The purpose of this study was to compare the rate of detection of intravascular injections during CMBBs using DSA and static images obtained through conventional fluoroscopy. Methods: Seventy-two patients were included, and a total of 178 CMBBs were performed. The respective incidences of intravascular injections during CMBBs using DSA and static images from conventional fluoroscopy were measured. Results: A total of 178 CMBBs were performed on 72 patients. All cases of intravascular injections evidenced by the static images were detected by the DSAs. The detection rate of intravascular injections was higher from DSA images than from static images (10.7% vs. 1.7%, P < 0.001). Conclusions: According to these findings, the use of DSA can improve the detection rate of intravascular injections during CMBBs. The use of DSA may therefore lead to an increase in the diagnostic and therapeutic value of CMBBs. In addition, it can decrease the incidence of potential side effects during CMBBs.

• Journal of Breast Cancer
• /
• v.21 no.4
• /
• pp.433-4341
• /
• 2018

Purpose: This study aimed to evaluate the effects of sentinel lymph node biopsy (SLNB) on recurrence and survival after neoadjuvant chemotherapy (NAC) in breast cancer patients with cytology-proven axillary node metastasis. Methods: We selected patients who were diagnosed with invasive breast cancer and axillary lymph node metastasis and were treated with NAC followed by curative surgery between January 2007 and December 2014. We classified patients into three groups: group A, negative sentinel lymph node (SLN) status and no further dissection; group B, negative SLN status with backup axillary lymph node dissection (ALND); and group C, no residual axillary metastasis on pathology with standard ALND. Results: The median follow-up time was 51 months (range, 3-122 months) and the median number of retrieved SLNs was 5 (range, 2-9). The SLN identification rate was 98.3% (234/238 patients), and the false negative rate of SLNB after NAC was 7.5%. There was no significant difference in axillary recurrence-free survival (p=0.118), disease-free survival (DFS; p=0.578) or overall survival (OS; p=0.149) among groups A, B, and C. In the subgroup analysis of breast pathologic complete response (pCR) status, there was no significant difference in DFS (p=0.271, p=0.892) or OS (p=0.207, p=0.300) in the breast pCR and non-pCR patients. Conclusion: These results suggest that SLNB can be feasible and oncologically safe after NAC for cytology-determined axillary node metastasis patients and could help reduce arm morbidity and lymphedema by avoiding ALND in SLN-negative patients.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.5
• /
• pp.1066-1072
• /
• 2011

In the method to analyze the relationship in the system call orders, the normal system call orders are divided into a certain size of system call orders to generates gene and use them as the detectors. In the method to consider the system call parameters, the mean and standard deviation of the parameter lengths are used as the detectors. The attack of which system call order is normal but the parameter values are changed, such as the format string attack, cannot be detected by the method that considers only the system call orders, whereas the model that considers only the system call parameters has the drawback of high positive defect rate because of the information obtained from the interval where the attack has not been initiated, since the parameters are considered individually. To solve these problems, it is necessary to develop a more efficient learning and detecting method that groups the continuous system call orders and parameters as the approach that considers various characteristics of system call related to attacking simultaneously. In this article, we detected the anomaly of the system call orders and parameters by applying the temporal concept to the system call orders and parameters in order to improve the rate of positive defect, that is, the misjudgment of anomaly as normality. The result of the experiment where the DARPA data set was employed showed that the proposed method improved the positive defect rate by 13% in the system call order model where time was considered in comparison with that of the model where time was not considered.

• Journal of Yeungnam Medical Science
• /
• v.16 no.2
• /
• pp.169-180
• /
• 1999

Background: Uterine cervical cancer is the most common malignant tumor of the women in Korea. This study was undertaken to evaluate the usefulness of the cervicography as a screening test of cervical cancer. Materials and Methods: Cervicography was taken from 482 women at department of obstetrics and gynecology, at Yeungnam University Hospital from March 1, 1998 to October 31, 1999. Of the 482 women, 172 women were exc1uded from the study for various reasons, and 310 women completed the study. Three-hundred and ten women had cervical cytology (Papanicolaou smear), cervicography and colposcopy, and punch biopsy was undertaken if any of the test result was abnormal. Results: The most common age group was 35-39, and 40-44, 45-49 in order and most common reason for having a screening test was regular check for cervical cancer. The mean duration from the last Pap smear was 17.1 months, and 64 women(20.4%) never had any prior screening tests. Of the 310 women, 254 women were categorized as normal or having benign disease such as cervicitis, erosion or metaplasia. Biopsy was taken from 56 patients and the results were 26 chronic cervicitis, 4 mild dysplasia, 6 moderate dysplasia, 2 severe dysplasia, 14 carcinoma in situ and 4 invasive carcinoma. The results of cytology and cervicography were well correlated(p<0.05). The sensitivity and specificity of cytology were 86.7% and 76.9%, respectively and the sensitivity and specificity of cervicography were 56.7% and 96.2%, respectively. False negative rate of cervicography(43.3%) was much higher than those of cytology(13. 3%) (p<0.05), but false positive rate of cervicography(3.8%) was much lower than that of cytology(23.1%) (p<0.05). Conclusion: It seems inappropriate to use cervicography as a single screening test for cervival cancer, but it may be an effective complementary test for cytology to lower the false negative rate of cytology.

• The Korean Journal of Cytopathology
• /
• v.12 no.1
• /
• pp.45-48
• /
• 2001

Acinic cell carcinoma(ACC) is the third common malignancy in major salivary gland. Fine needle aspiration cytology is a useful tool for the diagnosis of salivary gland lesions. However, some low grade malignancies, such as ACC and mucoepidermoid carcinoma show relatively high false negative rate, mainly due to deceptively benign cytomorphologic appearance. We experienced a papillary-cystic variant of ACC, having different cytopathologic features compared with those of classic ACC. Our case showed monolayered sheets and papillary clusters without any acinic structures or naked nuclei of the tumor cells. Foamy proteinaceous material was seen in the background. The tumor cells had a large amount of granular cytoplasm and eccentric nuclei. Many vacuolated or clear cells were also noted.

• Journal of Chest Surgery
• /
• v.31 no.11
• /
• pp.1085-1088
• /
• 1998

Background: In trauma patients, bony thorax are exposured to the trauma in many cases. With simple x-ray, we can not detect all definitive bony abnormalities, especially in less severe cases. Bone scan is very sensitive diagnostic method in such cases. Materials and methods: We experienced 680 cases and results were as follows. Results: 1. Diagnostic sensitivity was 97.4% and false negative rate was 2.6%. 2. In sensitivity study, the time factor(when we perform bone scan) was the most important thing according to trauma pattern. In rib fracture, sensitive test time was after 1 week. In sternal fracture, sensitive test time was after 1 week, too. In costochondral junction fracture and combined cases, it was after 3 days. Conclusions: We recommend timely using of bone scan as definitive diagnostic method in bony thorax trauma patients.