• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.120-120
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• 2011

Graphene is a carbon based material and it has great potential of being utilized in various fields such as electronics, optics, and mechanics. In order to develop graphene-based logic systems, graphene field-effect transistor (GFET) has been extensively explored. GFET requires supporting devices, such as volatile memory, to function in an embedded logic system. As far as we understand, graphene has not been studied for volatile memory application, although several graphene non-volatile memories (GNVMs) have been reported. However, we think that these GNVM are unable to serve the logic system properly due to the very slow program/read speed. In this study, a GVM based on the GFET structure and using an engineered graphene channel is proposed. By manipulating the deposition condition, charge traps are introduced to graphene channel, which store charges temporarily, so as to enable volatile data storage for GFET. The proposed GVM shows satisfying performance in fast program/erase (P/E) and read speed. Moreover, this GVM has good compatibility with GFET in device fabrication process. This GVM can be designed to be dynamic random access memory (DRAM) in serving the logic systems application. We demonstrated GVM with the structure of FET. By manipulating the graphene synthesis process, we could engineer the charge trap density of graphene layer. In the range that our measurement system can support, we achieved a high performance of GVM in refresh (>10 ${\mu}s$) and retention time (~100 s). Because of high speed, when compared with other graphene based memory devices, GVM proposed in this study can be a strong contender for future electrical system applications.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.139-145
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• 2012

Generally, Quicksort selects the pivot from leftmost, rightmost, middle, or random location in the array. This paper suggests Quicksort using middle range pivot $P_0$ and continually divides into 2. This method searches the minimum value $L$ and maximum value $H$ in the length n of list $A$. Then compute the initial pivot key $P_0=(H+L)/2$ and swaps $a[i]{\geq}P_0$,$a[j]<P_0$ until $i$=$j$ or $i$>$j$. After the swap, the length of list $A_0$ separates in two lists $a[1]{\leq}A_1{\leq}a[j]$ and $a[i]{\leq}A_2{\leq}a[n]$ and the pivot values are selected by $P_1=P_0/2$, $P_2=P_0+P_1$. This process repeated until the length of partial list is two. At the length of list is two and $a$[1]>$a$[2], swaps as $a[1]{\leftrightarrow}a[2]$. This method is simpler pivot key process than Quicksort and improved the worst-case computational complexity $O(n^2)$ to $O(n{\log}n)$.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.507-513
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• 2006

In this paper, we propose an improved image encryption and fault-tolerance decryption method using phase wrapping and phase encoding in the frequency domain. To generate an encrypted image, an encrypting key which denotes the product of a phase-encoded virtual image, not an original image, and a random phase image is zero-padded and Fourier transformed and its real-valued data is phase-encoded. The decryption process is simply performed by performing the inverse Fourier transform for multiplication of the encrypted key with the decrypting key, made of the proposed phase wrapping method, in the output plane with a spatial filter. This process has the advantages of solving optical alignment and pixel-to-pixel mapping problems. The proposed method using the virtual image, which does not contain any information from the original image, prevents the possibility of counterfeiting from unauthorized people and also can be used as a current spatial light modulator technology by phase encoding of the real-valued data. Computer simulations show the validity of the encryption scheme and the robustness to noise of the encrypted key or the decryption key in the proposed technique.

• Journal of Korean Society of Forest Science
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• v.3 no.1
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• pp.18-22
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• 1963

1. Objects The experiments of catalytic aharcoaling were carried out for the fallowing purposes. (1) To determine the economically desirable amount of catalytic materials to be used when a catalytic charcoaling is practiced. (2) To observe the rate of carbonization of non-treated charcoal wood when the catalytic charcoaling is proceeded in the same charcoal pit. 2. Meterials (1) Small sample chips made of oak (Q. accutissima Carr.), measured by 0.5cm in width and thickness, respectively, and 1cm in length, were used as charcoal wood in each experiment. (2) Ammonium chloride was used as a catalytic material and electric kiln as a charcoaling apparatus. 3. Experiment (1) The sample chips were put into a electric oven for three hours at the temperature $60^{\circ}{\sim}70^{\circ}C$ in order to reduce some water contents. (2) Oven dried sample chips were then soaked for an hour in solution of ammonium chloride. Three kinds of solution were prepared, that is, 2.5%, 5%, and 10%, solution in which the amount of ammonium chloride used was weighed at the rate of 0.5%, 1.0%, and 2.0% to the total weight of the sample chips, resppectivelly. (3) Soaked sample chips were put in the air for 12 hours to reduce some water contents, and then were put into electric oven for 2 hours at the temperature $105^{\circ}{\sim}110^{\circ}C$. (4) Dried sample chips were kept in a desiccator with control sample chips which were treated excarly the same process as the treated sample chips except only not using the ammonium chloride in the process of soking. (5) Sample chips kept in the desiccator were used at random in each charcoaling experiment. (6) Charcoaling in the electric kiln were carried out by using small crucibles with complete cover to reduce the amount of ash. At each charcoaling experiment four crucibles filled with sample ships, weighed about 20gr, were put into electric kiln. The charcoaling was continued for an hour at the temperature $400^{\circ}{\sim}450^{\circ}C$. (7) In order to investigate the influence given by the gases produced during the catalytic charcoaling to the rate of carbonization of non-treated sample chips, the following experiment was done. (a) A crueible was divided into two parts by inserting a fine iron net at the middle of the crucible, and then non-treated sample chips, weighed about 10gr, were put in the upper part of the crucible and treated sample chips, weighed also about 10gr, were put in the under part. (b) The crucibles filled with two kinds of sample chips were put into a electric kiln for an hour at the temperature $400^{\circ}{\sim}450^{\circ}C$. 4. Results. Results for two replications (with four crucibles in one replication) for each experiment designed are as follows : (1) The rats of carbonization of the non treated sample chips, and that of the treated sample chips with ammonium chloride at the rate of 1.5%, 1.0%, and 2.0% to the total weight of the sample chips used were averaged at 19.85%, 22.63%, 24.14%, and 26.60%, respectively. (2) The rats of carbonization of the non-treated sample chips were averaged at (a) 20.04% (0.5% treatment), (b) 20.28% (1.0% treatment), and (c) 20.61% (2.0% treatment) when the treated sample chips were carbonized in the same crucible.

• Korean Journal of Health Education and Promotion
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• v.26 no.2
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• pp.75-86
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• 2009

Objectives: To identify the factors associated with the intention to undergo mammography among Korean women without a prior screening experience. Methods: Among 1,039 women of the general population, we selected 145 women (mean age: 54.2 years, age range : 40-78 years) without any prior experience with mammography. They were recruited for the 'Cancer Information Needs Assessment Survey' by using the method of random multi-stage cluster sampling. Data on the socio-demographic characteristics, intention to undergo mammography based on the Precaution Adoption Process Model, level of self belief and self efficacy for breast cancer screening, motivation for decision to undergo breast cancer screening were obtained by conducting a household survey. Results: Of the study subjects, 49.7% were classified as "unengaged" and "decided not to act" regarding breast cancer screening. Women with the intention to undergo mammography were more likely to be younger (OR 0.11, 95%CI 0.04-0.36), to have been recommended to undergo screening by others (OR 3.27, 95%CI 1.36-7.87), to have a high level of perceived sensitivity (OR 3.15, 95%CI 1.27-7.82), and to have a high level of self efficacy (OR 1.09, 95%CI 0.97-1.23). Exposure to campaigns and information regarding breast cancer screening, whether cancer patients are or not in around, perceived severity, perceived benefit, and perceived cost were factors that were not significantly associated with the intention to undergo mammography. Conclusion: It is necessary to develop tailored intervention strategies for women who have never undergone breast cancer screening on the basis of their demographic characteristics and factors that positively influence the intention to undergo mammography.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.326-333
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• 2005

Phase-only encryption scheme using exclusive-OR rules in Fourier plane and a single path decryption system are presented. A zero-padded original image, multiplied by a random phase image, is Fourier transformed and its real-valued data is encrypted with key data by using XOR rules. A decryption is simply performed based on 2-1 setup with spatial filter by Fourier transform for multiplying phase-only encrypted data by phase-only key data, which are obtained by phase-encoding process, and spatial filtering for zero-order elimination in inverse-Fourier plane. Since the encryption process is peformed in Fourier plane, proposed encryption scheme is more tolerant to loss of key information by scratching or cutting than previous XOR encryption method in space domain. Compare with previous phase-visualization systems, due to the simple architecture without a reference wave, our system is basically robust to mechanical vibrations and fluctuations. Numerical simulations have confirmed the proposed technique as high-level encryption and simple decryption architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.649-658
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• 2006

Recently, Software Development was applied to new-approach methods as a various form : client-server system and web-programing, object-orient concept, distributed development with a network environments. On the other hand, it be concerned about the distributed development technology and increasing of object-oriented methodology. These technology is spread out the software quality and improve of software production, reduction of the software develop working. Futures, we considered about the distributed software development technique with a many workstation. In this paper, we discussed optimal release problem based on a stochastic differential equation model for the distributed Software development environments. In the past, the software reliability applied to quality a rough guess with a software development process and approach by the estimation of reliability for a test progress. But, in this paper, we decided to optimal release times two method: first, SRGM with an error counting model in fault detection phase by NHPP. Second, fault detection is change of continuous random variable by SDE(stochastic differential equation). Here, we decide to optimal release time as a minimum cost form the detected failure data and debugging fault data during the system test phase and operational phase. Especially, we discussed to limitation of reliability considering of total software cost probability distribution.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.362-362
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• 2010

Today, vast attention has been paid to periodic arrays of nanostructures due to their potential for applications such as memory with huge storage density. Such application requires large-scale fabrication of well ordered nano-sized structures. One of the most widely used methods for the ordered nanostructures is lithography. This top-down process, however, has the limit to reduce size. Here the promising alternative is the self-organization of ordered nano-sized structures such as large scale 2d carbon-induced reconstructions on W(110). In the present study, we report on the first well-resolved atomic resolution STM studies of the well-known R($15{\times}3$) and R($15{\times}12$) carbon induced reconstruction of the W(110). From the atomic image of R($15{\times}3$) for different values of tunneling gap resistance, we can tell there are no missing atoms in unit cells of R($15{\times}3$) and some atomic displacements are substantial from the clean W(110), even though not all the imaged position of atoms correspond to tungsten, but may include those of carbon. We are considering two cases; First case is related to lattice deformation, or top layer of W(110) is deformed in the process of relief of strain caused by random inserting of carbon atoms possibly in the interstitial position. In the second case, R($15{\times}3$) unit cell results from a coincidence lattice between clean W(110) substrate and tungsten carbide overlayer which has rectangular atomic arrangement and giving R($15{\times}3$) coincidence lattice. beta-W2C showing rectangular unit cell should be a candidate. Further, we report on new reconstructions. Unlike the well-known R($15{\times}12$) consisting of two parts, two inner structures between two "Backbone" structures. The new reconstruction, which we found for the first time, contains more parts between the "Backbone"s. Sometimes we can observe the reconstruction consists of only inner parts without "Backbone" parts. Thus, the observed reconstruction can be built by constructing of two types of "Lego"-like block. Moreover, the rectangle shape of "Backbone" transform to parallelogram-like shape over time, the so-called wavy-R($15{\times}12$). Adsorption of hydrogen can be the reason for this transformation.

• Journal of Preventive Medicine and Public Health
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• v.26 no.2 s.42
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• pp.293-309
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• 1993

With expanded and extended coverage of the national medical insurance and fast growing health care expenditures, appropriateness of health service utilization and quality of care are concerns of both health care providers and insurers as well as patients. An accurate patient classification system is a basic tool for effective health care policies and efficient health services management. A classification system applicable to Korean medical information-Korean Diagnosis Related Groups (K-DRGs)-was developed based on the U.S. Refined DRGs, and the performance of the developed system was assessed in this study. In the process of the development, first the Korean coding systems for diagnoses and procedures were converted to the systems used in the definition of the U.S. Refined DRGs using the mapping tables formulated by physician panels. Then physician panels reviewed the group definition, and identified medical practice patterns different in two countries. The definition was modified for the differences in K-DRGs. The process resulted in 1,199 groups in the system. Several groups in Refined DRGs could not be differentiated in K-DRGs due to insufficient medical information, and several groups could not be defined due to procedures which were not practiced in Korea. However, the classification structure of Refined DRGs was retained in K-DRGs. The developed system was evaluated fur its performance in explaining variations in resource use as measured by charges and length of stay(LOS), for both all and non-extreme discharges. The data base used in this evaluation included 373,322 discharges which was a random sample of discharges reviewed and payed by the medical insurance during the five-month period from September 1990. The proportion of variance in resource use which was reduced by classifying patients into K-DRGs-r-square-was comparable to the performance of the U.S. Refined DRGs: .39 for charges and .25 for LOS for all discharges, and .53 for charges and .31 for LOS for non-extreme discharges. Another measure analyzed to assess the performance was the coefficient of variation of charges within individual K-DRGs. A total of 966 K-DRGs (87.7%) showed a coefficient below 100%, and the highest coefficient among K-DRGs with more than 30 discharges was 159%.

• The Journal of Society for e-Business Studies
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• v.26 no.3
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• pp.97-117
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• 2021

Predicting term deposit subscriptions is one of representative financial marketing in banks, and banks can build a prediction model using various customer information. In order to improve the classification accuracy for term deposit subscriptions, many studies have been conducted based on machine learning techniques. However, even if these models can achieve satisfactory performance, utilizing them is not an easy task in the industry when their decision-making process is not adequately explained. To address this issue, this paper proposes an explainable scheme for term deposit subscription forecasting. For this, we first construct several classification models using decision tree-based ensemble learning methods, which yield excellent performance in tabular data, such as random forest, gradient boosting machine (GBM), extreme gradient boosting (XGB), and light gradient boosting machine (LightGBM). We then analyze their classification performance in depth through 10-fold cross-validation. After that, we provide the rationale for interpreting the influence of customer information and the decision-making process by applying Shapley additive explanation (SHAP), an explainable artificial intelligence technique, to the best classification model. To verify the practicality and validity of our scheme, experiments were conducted with the bank marketing dataset provided by Kaggle; we applied the SHAP to the GBM and LightGBM models, respectively, according to different dataset configurations and then performed their analysis and visualization for explainable term deposit subscriptions.