• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.124-125
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• 2000

We introduce a scheme with a maximized efficiency of detecting atoms passing through an optical standing-wave mode cavity. Consider a standing-wave optical cavity illuminated by a weak probe beam through one of its mirrors where the transmission through the other mirror is monitored by a photodetector. If an atom is put in the cavity, the atom-cavity coupling shifts the resonance frequency of the system via the so-called normal mode splitting, and thereby the transmission power will drop. In fact, this type of atom detection scheme has been used in recent single atom trap experiments In practice, however, the field in a standing-wave mode will have a geometrical structure having nodes and antinodes that when the atom traverses the cavity through one of the nodes, there will be no such effect of atom-field interaction. (omitted)

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.113-116
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• 2010

Ground cave-in is usually initiated by the formation of cavity within the ground due to soil loss. When the location of the cavity is deep in the ground, the detection of the cavity is not easy. Then it is possible that the hidden cavity expands for a long time to eventually cause sudden large-scale collapse. A case of large scale ground collapse in the old fill ground was studied and described in this paper. The underground cavity appeared to be caused by subsurface erosion deep in the ground and to expand/extend upward till it was ended by the catastrophic ground failure. It highlighted the importance of proper drainage work in a large scale land fill.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1135-1146
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• 2013

In this paper, we proposed a new algorithm for individual tooth region segmentation on tooth color images. The proposed algorithm used oral cavity model based on structural feature of tooth and new boundary of watershed algorithm. First, the gray scale image is obtained with emphasized tooth regions from the color images and unnecessary regions are removed on tooth images. Next, the image enhancement of tooth images is implemented using the proposed oral cavity model, and the individual tooth regions are segmented by watershed algorithm on the enhanced images. Boundary and seeds necessary to watershed algorithm are applied boundary of binary image using minimum thresholding and region maximum value. In order to evaluate performance of proposed algorithm, we conduct experiment to compare conventional algorithm with proposed algorithm. As a result of experiment, we confirmed that the proposed algorithm is more improved detection ratio than conventional algorithm at molar regions and the tooth region detection performance is improved by preventing overlap detection on oral cavity.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.376-383
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• 2005

In this study, we conducted geophysical investigations for the organization of integrated geophysical methods to detect underground cavities of ground subsidence area at the field test site, located at Yongweol-ri, Muan-gun. We examined the applicability of geophysical methods such as electrical resistivity, electromagnetic, and microgravity to cavity detection with the aid of borehole survey results. Underground cavities are widely present within the limestone bedrock overlain by the alluvial deposits in the area of the test site where the ground subsidences have occurred in the past. The limestone cavities are mostly filled with groundwater and clays in the test site. Thus, cavities have low electrical resistivity and density compared to the surrounding host bedrock. The results of the study have shown that the zones of low resistivity and density correspond to the zones of the cavities identified in the boreholes at the site, and that the geophysical methods used are very effective to detect underground cavities. Furthermore, we could map the distribution of cavities more precisely with the test results incorporated from the various geophysical methods. It is also important to notice that the microgravity method is a very promising tool since it has rarely used for the cavity detection in korea. Beyond the investigation of underground cavities, the geophysical methods are required to provide useful information for the reinforcement design for the ground subsidence areas. It is, therefore, necessary to develop integrated geophysical technique incorporating different geophysical methods to precisely map underground cavities and image the subsurface of the ground subsidence areas.

• Geophysics and Geophysical Exploration
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• v.6 no.2
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• pp.57-63
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• 2003

For the dectection of small cavity in the hard rock, we investigated the feasibility of crosswell travel-time tomography and Kirchhoff migration technique. In travel-time tomography, first arrival anomaly caused by small cavity was investigated by numerical modeling based on the knowledge of actual field information. First arrival delay was very small (<0.125 msec) and detectable receiver offset range was limited to 4m with respect to $1\%$ normalized first arrival anomaly. As a consequence, it was turned out that carefully designed survey array with both sufficient narrow spatial spacing and temporal (<0.03125 msec) sampling were required for small cavity detection. Also, crosswell Kirchhoff migration technique was investigated with both numerical and real data. Stack section obtained by numerical data shows the good cavity image. In crosswell seismic data, various unwanted seismic events such as direct wave and various mode converted waves were alto recorded. To remove these noises und to enhance the diffraction signal, combination of median and bandpass filtering was applied and prestack and stacked migration images were created. From this, we viewed the crosswell migration technique as one of the adoptable method for small cavity detection.

• International Journal of Oral Biology
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• v.48 no.2
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• pp.9-18
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• 2023

The rapid detection of bacteria in the oral cavity, its species identification, and bacterial count determination are important to diagnose oral diseases caused by pathogenic bacteria. The existing clinical microbial diagnosis methods are time-consuming as they involve observing patients' samples under a microscope or culturing and confirming bacteria using polymerase chain reaction (PCR) kits, making the process complex. Therefore, it is required to analyze the development status of substances and systems that can rapidly detect and analyze pathogenic microorganisms in the oral cavity. With research advancements, a close relationship between oral and systemic diseases has been identified, making it crucial to identify the changes in the oral cavity bacterial composition. Additionally, an early and accurate diagnosis is essential for better prognosis in periodontal disease. However, most periodontal disease-causing pathogens are anaerobic bacteria, which are difficult to identify using conventional bacterial culture methods. Further, the existing PCR method takes a long time to detect and involves complicated stages. Therefore, to address these challenges, the concept of point-of-care (PoC) has emerged, leading to the study and implementation of various chair-side test methods. This study aims to investigate the different PoC diagnostic methods introduced thus far for identifying pathogenic microorganisms in the oral cavity. These are classified into three categories: 1) microbiological tests, 2) microchemical tests, and 3) genetic tests. The microbiological tests are used to determine the presence or absence of representative causative bacteria of periodontal diseases, such as A. actinomycetemcomitans, P. gingivalis, P. intermedia, and T. denticola. However, the quantitative analysis remains impossible, and detecting pathogens other than the specific ones is challenging. The microchemical tests determine the activity of inflammation or disease by measuring the levels of biomarkers present in the oral cavity. Although this diagnostic method is based on increase in the specific biomarkers proportional to inflammation or disease progression in the oral cavity, its commercialization is limited due to low sensitivity and specificity. The genetic tests are based on the concept that differences in disease vulnerability and treatment response are caused by the patient's DNA predisposition. Specifically, the IL-1 gene is used in such tests. PoC diagnostic methods developed to date serve as supplementary diagnostic methods and tools for patient education, in addition to existing diagnostic methods, although they have limitations in diagnosing oral diseases alone. Research on various PoC test methods that can analyze and manage the oral cavity bacterial composition is expected to become more active, aligning with the shift from treatment-oriented to prevention-oriented approaches in healthcare.

• Imaging Science in Dentistry
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• v.53 no.1
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• pp.27-34
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• 2023

Purpose: The aim of this study was to clarify the influence of training with a different kind of lesion on the performance of a target model. Materials and Methods: A total of 310 patients(211 men, 99 women; average age, 47.9±16.1 years) were selected and their panoramic images were used in this study. We created a source model using panoramic radiographs including mandibular radiolucent cyst-like lesions (radicular cyst, dentigerous cyst, odontogenic keratocyst, and ameloblastoma). The model was simulatively transferred and trained on images of Stafne's bone cavity. A learning model was created using a customized DetectNet built in the Digits version 5.0 (NVIDIA, Santa Clara, CA). Two machines(Machines A and B) with identical specifications were used to simulate transfer learning. A source model was created from the data consisting of ameloblastoma, odontogenic keratocyst, dentigerous cyst, and radicular cyst in Machine A. Thereafter, it was transferred to Machine B and trained on additional data of Stafne's bone cavity to create target models. To investigate the effect of the number of cases, we created several target models with different numbers of Stafne's bone cavity cases. Results: When the Stafne's bone cavity data were added to the training, both the detection and classification performances for this pathology improved. Even for lesions other than Stafne's bone cavity, the detection sensitivities tended to increase with the increase in the number of Stafne's bone cavities. Conclusion: This study showed that using different lesions for transfer learning improves the performance of the model.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.15-29
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• 2002

Bayesian inversion for gravity and resistivity data was performed to investigate the cavity structure appearing as a lava tunnel in Cheju Island, Korea. Dipole-dipole DC resistivity data were proposed for a prior information of gravity data and we applied the geostatistical techniques such as kriging and simulation algorithms to provide a prior model information and covariance matrix in data domain. The inverted resistivity section gave the indicator variogram modeling for each threshold and it provided spatial uncertainty to give a prior PDF by sequential indicator simulations. We also presented a more objective way to make data covariance matrix that reflects the state of the achieved field data by geostatistical technique, cross-validation. Then Gaussian approximation was adopted for the inference of characteristics of the marginal distributions of model parameters and Broyden update for simple calculation of sensitivity matrix and SVD was applied. Generally cavity investigation by geophysical exploration is difficult and success is hard to be achieved. However, this exotic multiple interpretations showed remarkable improvement and stability for interpretation when compared to data-fit alone results, and suggested the possibility of diverse application for Bayesian inversion in geophysical inverse problem.

• The Journal of the Korean dental association
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• v.49 no.3
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• pp.136-145
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• 2011

Oral cavity cancer accounts for approximately 3-4% of all malignancies and is a significant worldwide health problem. The Korea Central Cancer Registry estimates that there will be approximately 1500 new cases of oral cancer in Korea. Oral cancer occurs most commonly in middle-aged and elderly individuals. The majority of oral malignancies occur as squamous cell carcinomas and despite remarkable advances in treatment modalities, the 5-year survival rate has not significantly improved over the past several decades, hovering at about 50% to 60%. The unfavorable 5-year survival rate may be attributable to several factors. First, oral cancer is often diagnosed at a late stage, with late stage 5-year survival rates as low as 22%. Additionally, the development of secondary primary tumors in patients with early stage disease has a major impact on survival. The early detection of oral cancer and premalignant lesions offers the promise to cure chance of oral cancer. The major diagnostics moddalities for oral cancer include oral cavity examination, supravital staining, oral cytology, and optical detection systems. But the clinical finding of oral mucosa is the most important key to confirm the oral cancer until now. The traditional clinical examination of oral cavity can be performed quickly, is without additional diagnostic expense to patients, and may be performed by health care professionals. Therefore, clinicians must be well-acquainted with clinical characteristics of oral cancer and practice routine screening for oral cancer in dental clinic to decrease the morbidity and mortality of disease.

• Radiation Oncology Journal
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• v.16 no.1
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• pp.87-90
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• 1998

Malignant melanoma of the oral cavity is rare, accounting for 1 to $8\%$ of all malignant melanomas. The overall prognosis remains poor despite the available treatments such as radical surgery, adjuvant radiotherapy, chemotherapy and immunotherapy due to failure in early detection and tendency in early metastasis. The etiology of mucosal malignant melanoma remains unkown. However, there are few cases of malignant melanoma of the oral cavity reported in the literature, which might be related to preexisting melanosis and radiation treatment. A case with malignant melanoma developed on the same site after 6 years following irradiation for squamous cell carcinoma of the oral cavity is reported in this article.