• Korean Chemical Engineering Research
• /
• v.55 no.1
• /
• pp.40-47
• /
• 2017

Dust explosion hazards are always present when combustible dusts are manufactured or handled in the process. However, industries is experiencing difficulty in establishing chemical accident prevention measures because of insufficiency of information on dust explosion characteristics of combustible dust handled in industry. In this study, we investigated experimentally dust explosion characteristics of two kinds of multi-walled carbon nano tubes (MWCNT) different in particle size distribution and examined classification of dust explosion hazardous area for MWCNT manufacturing or handling process by applying the NFPA 499 code. As a result, $P_{max}$, $K_{st}$, LEL, MIE and MIT of MWCNT 1 having $124.2{\mu}m$ median diameter are obtained 6.3 bar, $56bar{\cdot}m/s$, $125g/m^3$, over 1000 mJ, and over $650^{\circ}C$. $P_{max}$, $K_{st}$, LEL, MIE and MIT of MWCNT 2 having $293.5{\mu}m$ median diameter are 6.2 bar, $42bar{\cdot}m/s$, $100g/m^3$, over 1000 mJ, and over $650^{\circ}C$, respectively. MWCNT 1, 2 are not categorized as combustible dust listed in the NFPA 499 Code for classification of dust explosion hazardous area because explosion severity and ignition sensitivity of MWCNT 1, 2 are below 0.35 and 0.01, respectively.

• The Journal of the Korea Contents Association
• /
• v.16 no.2
• /
• pp.714-728
• /
• 2016

This research aims to categorize factors affecting reluctance of second childbirth among working mothers using Q methodology. P sample holds 50 working mothers between 20 and 45 years old living in Daegu-Gyeongbuk area. After securing the total 72 statements, the final 24 Q samples were confirmed through the second classification. As a result of this study, three types of the working mothers were classified. The first type that 22 working mothers (44%) were classified was "having uncooperative spouse". The second type which 13 working mothers (26%) were included was "working at not family-friendly workplace". Lastly, eight working mothers (16%) belonged to the third type, "having financial difficulty". Therefore, this study could confirm that the working mothers evade their second childbirth mostly because of the insufficient childcare support both at home and at work, rather than economic reasons. Thus, this study suggests that the Korean government should try to spread work-family balance culture than just providing financial support in order to encourage the second childbirth among working mothers.

• KIPS Transactions on Software and Data Engineering
• /
• v.8 no.3
• /
• pp.115-122
• /
• 2019

For Korean phoneme recognition, Hidden Markov-Gaussian Mixture model(HMM-GMM) or hybrid models which combine artificial neural network with HMM have been mainly used. However, current approach has limitations in that such models require force-aligned corpus training data that is manually annotated by experts. Recently, researchers used neural network based phoneme recognition model which combines recurrent neural network(RNN)-based structure with connectionist temporal classification(CTC) algorithm to overcome the problem of obtaining manually annotated training data. Yet, in terms of implementation, these RNN-based models have another difficulty in that the amount of data gets larger as the structure gets more sophisticated. This problem of large data size is particularly problematic in the Korean language, which lacks refined corpora. In this study, we introduce CTC algorithm that does not require force-alignment to create a Korean phoneme recognition model. Specifically, the phoneme recognition model is based on convolutional neural network(CNN) which requires relatively small amount of data and can be trained faster when compared to RNN based models. We present the results from two different experiments and a resulting best performing phoneme recognition model which distinguishes 49 Korean phonemes. The best performing phoneme recognition model combines CNN with 3hop Bidirectional LSTM with the final Phoneme Error Rate(PER) at 3.26. The PER is a considerable improvement compared to existing Korean phoneme recognition models that report PER ranging from 10 to 12.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.5
• /
• pp.1921-1929
• /
• 2015

The smart substation is the heart of a transmission system, which is particularly emphasized as the most significant composition of smart grids in China. In order to assess the functionality performance of substation technologies, this paper presents methods used to identify the most promising solutions for smart substation design and to evaluate the technical levels of available technologies. The multi-index optimization model is presented to address the issue of smart substation planning. A mathematical model of the planning decision problem is established with multiple objectives consisting of economic, reliability, and green key indices, and many kinds of concerns including physical and environmentally friendly operations are formulated as a set of constraints. With respect to the assessment of the technical level regarding integration of advanced technologies into a substation, a modified grey whitenization weight function is adopted to structure a novel grey clustering method. The proposed grey clustering approach is used to overcome the difficulty of insufficient quantitative assessment capacity for traditional methods. The evaluation of technical effects provides the classification definition for the development phase and the maturity level of the smart substation. The effectiveness of the proposed approaches in planning decision-making and evaluation of construction efforts is demonstrated with case studies involving the actual smart substation projects of Wenchongkou substation in China Southern Power Grid (CSG) and Mengzi substation in State Grid Corporation of China (SGCC).

• Journal of Oriental Neuropsychiatry
• /
• v.22 no.3
• /
• pp.23-42
• /
• 2011

Objectives : The purpose of this study was to investigate the difference of somatization psychological mechanism among Sasang constitution. Methods : Subjects were seventy four students of Won-Kwang university responded the questionnaire. We evaulated the subjects using Minnesota Questionnaire for the Sasang Constitution Classification II(QSCC II), Multiphasic Personality Inventory-2(MMPI-2), 20-item Toronto Alexithymia Scale (TAS-20), Somato-Sensory Amplification Scale(SSAS), Symptom Interpretation Questionnaire(SIQ) and The Ways of Stress Coping Questionnaire(SCQ). Results : From the results of Clinical scale of MMPI-2, the scores of 2nd, 9th, 10th scales was significantly difference. In Lesser Yin group 10th score was the significantly highest of the others, 1st, 3rd, 6th, 7th, 8th score were the highest but not significant. and From the results of PSY-5 scale(The Personality Psychopathology Five scale) of MMPI-2, In Lesser Yin goup, INTR(Introversion/Low Positive Emotion) score was significantly highest, PSYC(psychoticism), NEGE (Negative Emotionality/Neuroticism) was higher than the others. In TAS-20K, SSAS, SIQ and SCQ Lesser Yin group was not significantly difference. but Lesser Yin group had the tendency of difficulty describing feelings and externally oriented thinking and higher score in physical and psychological interpretation. We observed generally lower levels of stress coping strategy scores than the others. Conclusions : These results showed that Lesser Yin group tend to somatization compared other constitution.

• Journal of The Korean Dental Society of Anesthesiology
• /
• v.9 no.1
• /
• pp.24-29
• /
• 2009

When performing the inferior alveolar nerve block anesthesia, surgeon often faced a difficulty of the surgical operation due to the incomplete anesthesia. One of the reason is the variety of mandibular canal anatomy. Up to now, there are some reports of index cases about bifid mandibular canal among mandibular canal anatomic variation, and some classification is applied according to anatomical location and configuration. When surgical operation is performed involving mandible such as dantal implant treatment, extraction of an impacted third molar, sagittal split ramus osteotomy, etc, the position of mandibular canal should be considered. Bifid mandibular canal clinically causes troublesome cases of anesthesia when inferior alvelor nerve block, especially is performed extraction of an impacted third molar. Therefore, It is important for clinicians to recognize the presence of bifid canals on radiographys. Nowadays, the position of mandibular canal can be measured precisely by using Dental CT. It is not found by panorama image but is found by Dental CT sometimes. Among the patients, which take panorama and Dental CT simultaneously, for tooth extraction of lower impacted third molar in our department, we report the case that did not identifying in panorama but identifying it in Dental CT.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.34 no.6
• /
• pp.611-615
• /
• 2008

The prognosis of oral malignant melanoma is poor compared with cutaneous melanoma. It may be related to the difficulty of wide enough resection, the early hematogenous matastases, higher stage at initial diagnosis, and tendency to growth vertically. In the view of histological differences between oral mucosa and skin, it is impossible use Clark's and Breslow's classifications for prognosis. The great problem is that there is still no consensus on the treatment due to rarity. Because data collection from case reports is considered to be the best source of information and should be pooled to analyze key determinants of outcome, We analysed 6 cases of primary malignant melanoma of the oral cavity which were diagnosed and treated in Pusan National University Hospital on recent 7 years and reviewed the literatures. Immunohistochemical study on S 100 Protein, GP 100 (HMB-45) with biopsy was usable to confirm the melanoma. Three patients who were treated by surgery, chemotherapy are alive, but a patients who couldn't received benefit care surgically due to poor condition was died of distant metastasis, and two patients who refused to surgery are still alive. Neck dissection including wide excision is recommended if lymph node involvement is suspected. Additionally, adjuvant chemotherapy could be considered as supporting therapy for malignant melanoma.

• Journal of the Korean Society of Costume
• /
• v.59 no.8
• /
• pp.49-65
• /
• 2009

As basic materials in this research, 874 pieces of engraving that recorded the garment produced by diverse authors in the 17-18th century were collected among the collections of male and female garment in the engraving kept by National Library of France and 216 pieces of engraving were classified among them to observe justaucorps as stated in the materials. Since type of justaucorps in the 18th century can be classified by difference in shape and change through the above engraving materials in large quantity and the shape and composition can be compared and analyzed with other materials such as picture, stored garment, written materials without difficulty, the chronology can be composed by single type of justaucorps. Intending to understand the change in composition caused by type classification and pattern making as per analysis of type property of justaucorps, the men's upper garment in France in the 18th century. Checking change in design per from and materials, justaucorps of 1680-1700s was in silhouette where waist in the length above knee was adhered and slightly spread to lower part. In the type of 1710-1750s, waist adhered remarkably and many pleats were made under waist to produce volume of form that spread to lower part like skirt. In the type of 1760-1780s, straight silhouette was attached to whole body and end of front adjustment in slant line turns to rear part. The developmental aspect of construction can be checked by making pattern. Changing the cutting line of body plate to smoothly connect section and to try to adhere to the body, the development of simpler and delicate pattern production technique was confirmed.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.11 no.1
• /
• pp.82-96
• /
• 2019

A semi-submersible structure has been widely used for offshore drilling and production of oil and gas. The small water plane area makes the structure very sensitive to weight increase in terms of payload and stability. Therefore, it is necessary to lighten the substructure from the early design stage. This study aims at an optimization of hull structure based on a sophisticated yield and buckling strength in accordance with classification rules. An in-house strength assessment system is developed to automate the procedure such as a generation of buckling panels, a collection of required panel information, automatic buckling and yield check and so on. The developed system enables an automatic yield and buckling strength check of all panels composing the hull structure at each iteration of the optimization. Design variables are plate thickness and stiffener section profiles. In order to overcome the difficulty of large number of design variables and the computational burden of FE analysis, various methods are proposed. The steepest descent method is selected as the optimization algorithm for an efficient search. For a reduction of the number of design variables and a direct application to practical design, the stiffener section variable is determined by selecting one from a pre-defined standard library. Plate thickness is also discretized at 0.5t interval. The number of FE analysis is reduced by using equations to analytically estimating the stress changes in gradient calculation and line search steps. As an endeavor to robust optimization, the number of design variables to be simultaneously optimized is divided by grouping the scantling variables by the plane. A sequential optimization is performed group by group. As a verification example, a central column of a semi-submersible structure is optimized and compared with a conventional optimization of all design variables at once.

• Korean Journal of Head & Neck Oncology
• /
• v.20 no.1
• /
• pp.24-28
• /
• 2004

Background and Objectives: Salivary gland tumors are relatively rare and constitute 3% to 4% of all head and neck neoplasms. Their relative infrequency, inconsistent classification, and highly variable biologic behavior make some difficulty, but some general features can be drawn regarding the incidence, pathology, and pattern of behavior of the various benign and malignant tumors of salivary glands. The present study aims to provide a clinical characteristics of salivary gland tumors. Materials and Methods: We analyzed retrospectively clinical features of the 138 patients who were treated surgically at Chonbuk National University Hospital from 1992 through 2002. Results: We found 107 benign and 31 malignant tumors. Among the patients, 58 were males and 80 were females. The most common age group was the fifties. The most common site of both benign and malignant was parotid gland in major salivary glands and palatal region in minor salivary glands. The most common presenting symptom was palpable mass in both benign and malignant tumor. Histopathologically, the most common type was pleomorphic adenoma in benign tumor and mucoepidermoid carcinoma in malignant tumor. All cases were treated surgically and the most common postoperative complications was transient facial nerve weakness. Conclusion: 138 cases of salivary gland tumors were presented with respect to their clinical features.