diff --git a/HamSungJun/BinarySearch/Solution_392.ts b/HamSungJun/BinarySearch/Solution_392.ts
new file mode 100644
index 0000000..0a5ff3a
--- /dev/null
+++ b/HamSungJun/BinarySearch/Solution_392.ts
@@ -0,0 +1,11 @@
+function isSubsequence (s: string, t: string): boolean {
+  let ps = 0
+  let pt = 0
+  while (pt < t.length) {
+    if (s[ps] === t[pt]) {
+      ps += 1
+    }
+    pt += 1
+  }
+  return ps > s.length - 1
+};
diff --git a/HamSungJun/BinarySearch/Solution_704.ts b/HamSungJun/BinarySearch/Solution_704.ts
new file mode 100644
index 0000000..a3937ab
--- /dev/null
+++ b/HamSungJun/BinarySearch/Solution_704.ts
@@ -0,0 +1,15 @@
+function search (nums: number[], target: number): number {
+  let left = 0
+  let right = nums.length - 1
+  while (left <= right) {
+    const mid = Math.floor((left + right) / 2)
+    if (nums[mid] === target) {
+      return mid
+    } else if (nums[mid] < target) {
+      left = mid + 1
+    } else if (nums[mid] > target) {
+      right = mid - 1
+    }
+  }
+  return -1
+};
diff --git a/HamSungJun/BinarySearch/Solution_852.ts b/HamSungJun/BinarySearch/Solution_852.ts
new file mode 100644
index 0000000..2e0b1ac
--- /dev/null
+++ b/HamSungJun/BinarySearch/Solution_852.ts
@@ -0,0 +1,8 @@
+function peakIndexInMountainArray (arr: number[]): number {
+  for (let i = 1; i < arr.length; i++) {
+    if (arr[i - 1] < arr[i] && arr[i] > arr[i + 1]) {
+      return i
+    }
+  }
+  return -1
+};